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This reproduction was made by the Soil and Health Library only for the purpose of research and study. Any further distribution or reproduction of this copy in any form whatsoever constitutes a violation of copyrights. PAULINA WOJCIECHOWSKA

THE REAL GOODS SOLAR LIVING BOOKS

This Organic Life: Confessions of a Suburban Homesteader by Joan Gussow

The Beauty of Straw Bale Homes by Athena and Bill Steen

Serious Straw Bale: A Home Construction Guide for All Climates by Paul Lacinski and Michel Bergeron

The Natural House: A Complete Guide to Healthy, Energy-Efficient, Environmental Homes by Daniel D. Chiras

The New Independent Home: People and Houses that Harvest the Sun, Wind, and Water by Michael Potts

Wind Energy Basics and Wind Power for Home & Business by Paul Gipe

The Earth-Sheltered House: An Architect's Sketchbook by Malcolm Wells

Mortgage-Free! Radical Strategies for Home Ownership by Rob Roy

A Place in the Sun: The Evolution of the Real Goods Solar Living Center by John Schaeffer and the Collaborative Design/Construction Team

The Passive Solar House: Using Solar Design to Heat and Cool Your Home by James Kachadorian

Independent Builder: Designing & Building a House Your Own Way by Sam Clark

The Rammed Earth House by David Easton

The Straw Bale House by Athena Swentzell Steen, Bill Steen, and David Bainbridge with David Eisenberg

Real Goods Solar Living Sourcebook: The Complete Guide to Renewable Energy Technologies and Sustainable Living,

10th Edition, edited by Doug Pratt and John Schaeffer

REAL GOODS TRADING COMPANY in Ukiah, California, was founded in 1978 to make available new tools to help people live self- sufficiently and sustainably. Through seasonal catalogs, a periodical (The Real Goods News), a bi-annual Solar Living Sourcebook, as well as retail outlets and a Web site (www.realgoods.com), Real Goods provides a broad range of tools for independent living. "Knowledge is our most important product" is the Real Goods motto. To further its mission, Real Goods has joined with Chelsea Green Publishing Company to co-create and co-publish the Real Goods Solar Living Book series. The titles in this series are written by pioneering individuals who have firsthand experience in using innovative technology to live lightly on the planet. Chelsea Green books are both practical and inspirational, and they enlarge our view of what is possible as we enter the new millennium.

Title page photograph is used courtesy of Hartworks, Inc. I dedicate this book to all my teachers in the world of Extract on page xi is from Eco Design Journal, vol. 3, no. 3, 1995. natural building, and I thank each one of you for all the

All rights reserved. No part of this book may be transmitted in any form by any tremendous knowledge and help: Trevor Garnham of Kingston means without permission in writing from the publisher. University, who taught me throughout most of my architectural

Printed in the United States. education and whose idea it was to write this book; Nader Khalili First printing, June 2001 and Illona Outram of Cal-Earth, the pioneers of earthbag

04 03 02 01 12345 Superadobe construction; Athena and Bill Steeen of the Canelo Project; Tom Watson, the silent inventor of, Printed on acid-free, recycled paper. among many things, Pumice-crete; and all the others

Due to the variability of local conditions, materials, skills, site, and so forth, Chelsea whom I met on the way who taught me Green Publishing Company and the author assume no responsibility for personal and took great care of me. injury, property damage, or loss from actions inspired by information in this book. Always consult the manufacturer, applicable building codes, and the National Electric Code. When in doubt, ask for advice. Recommendations in this book are no substitute for the directives of professional contractors, equipment manufacturers, or federal, state, and local regulatory officials.

Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book and Chelsea Green was aware of a trademark claim, the designations have been printed in initial capital letters.

Library of Congress Cataloging-in-Publication Data Wojciechowska, Paulina, 1967- Building with earth: a guide to flexible-form earthbag construction/ Paulina Wojciechowska. p. cm. — (A Real Goods solar living book) Includes bibliographical references and index. ISBN 1-890132-81-0 (alk. paper) 1. Earth construction. I. Title. II. Series.

TH1421 W597 2001

693'.91—dc2i 2001028676 CHELSEA GREEN PUBLISHING COMPANY Post Office Box 428 White River Junction, VT 05001 (800) 639-4099 www.chelseagreen.com CONTENTS

Acknowledgments ix 3. GETTING STARTED: DESIGN, 4. BUILDING WITH EARTHBAGS 43 6. WEATHERPROOFING AND Introduction xiii FINISHES 75 SITING, AND FOUNDATIONS 29 Materials 44 Design Considerations 29 Tools 46 Earthen Plasters 76 1. EARTH ARCHITECTURE 3 Locating the Building on the Preparing the Fill 49 Application 77 Clay-Based Building Materials 5 Land 29 Filling Bags or Tubes 50 Stabilization and Alternatives 78 Adobe 6 Landscaping 30 Filling a Bag with More than Three Vegetable Stabilizers 81 Cob 8 Topography 30 People 51 Animal Products as Stabilizers 82 Mineral Stabilizers: Lime 82 Rammed Earth 9 Orientation 31 Filling Bags or Tubes with Only Lime Plasters 83 Wattle and Daub 10 One to Three People 52 Utilities 32 Making Lime Putty (Slaking) 84 Straw-Clay 10 Building Shape 32 Using Small Bags 52 Making Lime Plaster or Render 86 Papercrete 11 Planning Ahead 33 Tamping 52 Application 87 Earthbags 12 Site Preparation: Setting Out 33 Keying 54 Pozzolanic Additives to Lime Structural Reinforcement and When Are Earthbags Appropriate? 16 Foundations 34 Plaster 87 Buttressing 54 Extending or Recycling the Earth-Filled Tires 39 Stabilization for Waterproofing 88 Openings 57 Building 17 Rubble or Mortared Stone 39 Arched Openings 58 Stabilization with Cement 89 Earthbags Forever 19 Gabions 40 Square Openings 60 Application of Stabilized Renders 91 Dry-stone 40 Bond Beams 60 Interior Finishes 92 2. USING BASIC STRUCTURES Pumice-crete 40 Sealants 92 FROM NATURE TO BUILD 5. ROOFS 65 Paints 94 WITH EARTH 21 Clay Slip or Alis 95 Brick or Adobe Roofs 66 To Cook Wheat Flour Paste 96 Arches 22 Vaulted Roofs 67 To Make Alis Clay Paint 96 Making the Arch 24 Conventional Roofs 68 Application 97 Vaults 24 Water-Catchment Roofs 68 Lime Paint or Whitewash 97 Apses 26 Thatched Roofs 68 Additives to Lime Wash 97 Domes 26 Living Roofs 70 Recipes for Water-Resistant Whitewash 97 Corbeling 26 Low-cost Flat Roofs 71 Some Old Limewash Recipes 98 Roof Insulation 72 viii

ACKNOWLEDGMENTS

Casein 98 8. THE EARTHBAG I would like to give special thanks to Nader Khalili and Iliona Outram, Bill Recipe for Interior-Exterior ADVENTURE 123 and Athena Steen, and Tom Watson for their generosity in everything they Casein 99 gave throughout the many months of my travels, which enabled me to write Application 100 Shirley Tassencourt's Domes, this book. Oil-Based Paints 100 Arizona 123 I would like to express my gratitude to all those who helped me put this Maintenance 100 Allegra Ahlquist's House, Arizona 127 book together in many different ways, some of whom I mention below: House Built by Dominic Howes, From Kingston University, I would like to thank the Green Audit 7. OTHER INTERIOR WALLS, Wisconsin 128 Research Project for partly funding and enabling me to commence the FLOORS, AND FURNISHINGS: Sue Vaughan's House, Colorado 130 writing of this book. Thanks to Peter Jacob, Bryan Gauld, and Sue Ann Lee. BUILDING WITH CLAY 103 Carol Escott and Steve Kemble's Also to Trevor Garnham for guiding me through the process. From the Finding and Analyzing Building House, the Bahamas 131 Green Audit room at Kingston University: Cigdem Civi, Helen Iball, and Soils 103 Kelly and Rosana Hart's House, David Lawrence. Jar Test 104 Colorado 135 Friends in England whose help was invaluable: Flora Gathorne Hardy for Testing by Hand 105 Kaki Hunter's and Doni Kiffmeyer's her help, photographs, and immense support and belief in this book; also to The Right Mix 105 Honey House, Utah 140 Salim Khan, Bruce Ure, and Shahnawaz Khan for their technical support; Thin Partitions and Ceiling The Lodge "Njaya," Malawi 142 and to Tim Crosskey, Henry Amos, Wasim Madbolly, and Max Jensen for Panels 109 The New House of the Yaquis, the photographs; and to Adrian Bunting for the Malawi project. Insulation 110 Mexico 143 Straw-Light Clay 111 Friends who contributed their stories and photographs in the United States: in Arizona, Bill and Athena Steen, also Allegra Ahlquist, Shirley Hybrid Earthbag and Straw Bale 113 Afterword 148 Tassencourt, and Dominic Howes, who shared information as well as huge Interior Detailing 114 Bibliography 149 amounts of love and support throughout the whole process, together with Earthen Floors 115 Resources 153 Carol Escott and Steve Kemble, and a very big thank you for being there in Construction 118 Index 158 Sealants, Maintenance, and those very difficult times. In California: Michael Huskey. In Colorado: Kelly Repair 119 and Rosana Hart. In Utah: Kaki Hunter and Doni Kiffmeyer. In New Electricity and Plumbing 120 Mexico: Joseph Kennedy. Also I would like to thank Ian Robertson in California for his support, Gene Leon for early editing, Frank Haendle in Germany for communica- X

tions, Lydia Gould for all the survival help in Mexico, and Athena and Bill Steen for making that trip possible. It is impossible to name all the people to whom I am very grateful, who were so wonderful throughout my travels, but I would like to quickly mention some not yet named, who looked after me and helped me to make my journeys: Simon Clark, John Jopling, Vanita and Alistair Sterling, Heidi Koenig, Catherine Wanek and Pete Fust, Satomi and Tom Landers, Kat Morrow, Karen Chan, Carole Crews, Cedar Rose, Lynne Elizabeth, Cassandra Adams, Leonard Littlefinger, Lance Charles, Ralf and Rina Swentzell, Arin Reeves, George Mohyla, Doc Clyne, Giovani Panza, Craig Cranic, Michael Smith, Elizabeth Lassuy, Reto Messmer, Kevin Beale, Stokely Webster, Monika Falk, and Christina and Markus Lehman. Without my family, who provided me with constant help and support, the "journey" and the writing would have been more difficult. I would like to thank my parents, Marcjanna Sojka and Krzysztof Wojciechowski, and my stepfather, Witold Sojka. My special thanks are extended to my partner, Christof Schwarz, who has endured many absences and who has provided constant support, encourage• ment, and help with writing this book, for which I am immensely grateful. Finally, my thanks to the publishing team at Chelsea Green, especially Jim Schley, Hannah Silverstein, Ann Aspell, and Rachael Cohen, who have carefully edited the text, illustrations, and photographs. ... being surrounded by beauty allows one to put aside at least some of the burden of his

or her defences against the world and to feel inwardly free. What relief! What therapy!

Unlike composition, harmony and so on, beauty rules. It is something the artist must struggle

to achieve. And anyone who undertakes this struggle, with all the single-minded dedication it demands,

is an artist. This love force shines from the finished product. It has nothing to do with fashion or style,

and little to do with latent ability. It comes from the gift of love, and an environment

so filled has a powerful healing effect,for love is the greatest healer, needing

only understanding to complete it.

—Christopher Day, from "Human Structure and Geometry" INTRODUCTION

had a wish—to be able to go to any take a path other than the so-called mod• place on this Earth and build a shelter ern way. Iwith the materials available to me Most primitive buildings were con• from the surrounding environment. I had structed by an anonymous builder in re• already learned about building with wood, sponse to such conditions as climate, ori• stone, clay, straw, lime, and many combi• entation, and the availability of building nations and permutations of all these. The materials. Building materials dictated the material that would fill in the gap, that form of each structure. The builders were would give me the complete confidence sensitive to their materials; they worked that I would be able to build a house al• with them, not against them as so much of most anywhere, was sand. today's architecture seems to do. I spent most of the impressionable A few years ago, I was working in an ar• years of my life in Afghanistan and India, chitectural office. I was always at the draw• where I was surrounded by indigenous ar• ing board doing technical drawings, not chitecture. It was during that time, I sus• really understanding the materials I was pect, that I developed a passion for hon• working with or why they were used. How esty, modesty, and harmony in design. All were critical decisions made? Did the best the way through my architectural studies, choices depend on cost, aesthetics, or sur• I was drawn to what I call "primitive" ar• roundings, or was the process driven by chitecture. By "primitive" I don't mean people who were just stuck in their ways, Facing page: Earthen backward, but quite the opposite. To be dictating by convention and code how structures at Cal-Earth, California. primus means to be the first, to be at the buildings should be designed? In time, I beginning: primary. It is good for the mind realized that to find another way I had to to go back to the beginning, because the learn by using my hands. It was necessary beginning of any established human activ• for me to experience actual construction, a ity is often its moment of greatest wonder. time of very basic building. Always start The original forms can teach us the fun• with the basics—the first principle of damental principles of each invention, natural building. showing us the possibility that we might An opportunity came up to participate xiii xiv INTRODUCTION XV

in a workshop for people who wanted to which is exactly what I needed after all Here is an extract from my diary, describing my thoughts when learn to build. It was to be three intense those years at the drawing board. It was I first arrived at Cal-Earth: weeks of building a house for the Othona great! These experiences reinforced my Community Retreat in Dorset, England. need to go away to places where people It's early morning as I step outside the house. Mist covers the The course was run by Simon Clark of were building using basic principles and bottom of the mountains, silhouettes of shabby Joshua trees, a Constructive Individuals, an organization materials, places that would give me more tree that stands so still all the time. The sand is lit up, the in London that offers training to people opportunity to discover indigenous build• mountain towers above the mist. The cold is sharp, the sun is who wish to build their own homes or ex• ing materials and techniques, freed from bright. In the foreground I see domes and desert architecture, tend or alter an existing dwelling, or who the rigid commercialism of London archi• like sand dunes. The landscape looks and feels right. Instead of simply want to have the building process tecture. destroying the view of the mountain beyond and Joshua trees demystified. How wonderful this oppor• In the autumn of 1996, I finally em• around and the vast openness, the structures enhance the view. tunity sounded, to build a whole house in barked on my long-awaited journey. My I do not feel disturbed by their presence. Quite the opposite; I just three weeks! I jumped at the chance. first three-month stop was at the Califor• am happy they exist and have become an integral part of this The course covered construction tech• nia Institute of Earth Art and Architecture landscape. I walk toward them, at first looking around the niques and also raised many ecological is• (Cal-Earth). Set up by Iranian-born archi• outside. I realize that they are sunken into the ground. They sues. This particular home was designed to tect and author Nader Khalili and his Brit• feel very solid and permanent. Yes, they have this permanence have minimal impact on the environment ish associate Iliona Outram, this school and belonging about them, a permanence that a timber house by using recycled-newspaper insulation, a takes people on apprenticeship retreats for does not have. Once I walk inside, they feel cool. They have The author's earthbag retreat before plastering. composting toilet system, solar electric a week or more. During this time, Cal- soaked up the night's cold air. I am drawn toward the one that modules, a graywater system, and a leach- Earth and its associates contributed to looks like an animal. It has a fireplace and a small niche to hide field to nourish fruit trees. There it all was, teaching me of the "magic" simplicity of in. Ideas flow into my mind of a house I would like to build and it had a name: Ecological, Sustainable, earth architecture. Working with the earth right now for myself, with a network of rooms all interconnect• and Environmental. These were the words empowered me to carry on, as it has em• ing, partly underground. The outside is very intriguing as well. used for the simpler ways of building I had powered many other individuals. I learned I imagine patterns forming from the way the plaster has been dreamed of. I knew that after this work• the basics of earthbag construction (called applied and outlined. After a while, I proceed to the other shop I would know what to ask for. A whole Superadobe at Cal-Earth) and spent time attractive-looking earth shelter. This one is totally covered in Interior of the author's new world was opened to me. researching this method, trying to push its earth, or so it appears. It has tiny circular windows going all Earthmother Dwelling After the Dorset course, I became much limitations and explore its possibilities. around at the lower level, great for children if they want to look retreat. out. The light at sunrise is amazing; it floods in though one more confident in handling tools, and To simplify is the aim. What a joy to The author's retreat during plastering. many of the mysteries behind building a learn and to fulfill my dreams! I spent a larger window. Because of the partially white wall, the room house were gone. I had finally experienced wonderful three months, studying as well looks bright. The primitive paintings on the wall stand out. what it felt like to build. I got to "feel" the as building my own retreat. For the first The light covers the horizon; the sun is a little higher, but the materials, feel what concrete is like, feel time in my life I could design and build a air is still sharp. I sit in the sun's rays to warm myself. what working with wood is like, and learn house with no restrictions from anyone. I After some time I get up and walk into a brick dome. The how all the pieces go together. I also expe• was free and I felt free and therefore I ex• light beautifully percolates through the bricks. The top of the rienced the harsh realities of building, pressed freedom. dome is open. This one feels the coldest so far, probably xvi INTRODUCTION xvii

because none of the openings are traditionally, for example in Islamic archi• points for observing who was approach• like sculpting. When sculptors carve rock, glazed, and I feel the air moving tecture. Rather, this passion has to do with ing. The seating areas were to be niches so they listen to the rock telling them what it through. I walk to the center. The the prevalence of arched forms in nature. I three or four people could sit facing each needs to become. Designing and building acoustics are amazing. The sounds that did not necessarily want to imitate nature. other. And a child who lay sleeping in a a dwelling is likewise about understanding I make with my feet bounce around I wanted to experience the freedom that niche would be able to see the fire burning the material, the needs and passions of the and seem very loud. What a great place nature appears to possess. I had experi• opposite, for comfort. I wanted the ceiling inhabitants, and the climate and other to play music this would be. After a enced so many constraints in the world I to be high, since we often judge a space by characteristics of the site. The challenge is short pause, I proceed to the Three came from that I wanted to escape rules its volume. Although the main room was to be in harmony with your environment, Vault House. Whoa! Rectangular and regularity. I wanted to become free. only 10 feet (3 meters) in diameter, ten and most of all to feel passion during the rooms, white walls—it feels like a So my ideas just came as I went along. people could sit comfortably inside with• process. chapel. A lot of different-sized open• Later, looking back, I could translate these out feeling claustrophobic. To me this is what contributed to my ings and niches in the walls. A cooling ideas into theories about design and con• An earthbag dome sunken into the retreat's soul. tower under construction. A very large struction, but that is not how it started. ground creates and encloses a space. Bas• From the moment I started to build, I space in comparison to the others. The The accompanying drawings and photos ing your design upon that central enclo• recognized that it was essential to main• light reflects off the walls in a soothing give a sense of how I went about designing sure, you can add or take away as you tain trust in the material. Without this to• way. It feels airy and open. There are and building the retreat. please and as the structure allows. Building tal trust, you fall back upon narrow ideas. more buildings here than I expected— To begin with, I spent many days look• with earthbags is not like digging a cave, To push any process forward, you need but what did I expect? ing around the site thinking about where scraping away at the earth to hollow out trust. Unless you build with feeling, you to place my tiny retreat. I found a lovely the shape of the building, and it's not like a will not feel true contentment with the fin• My desire to build using the earth, uti• spot, away from other structures. A lonely wooden or concrete house where every• ished product. When you merge the natu• lizing the earthbag technique, was very Joshua tree stood in a clearing of sorts. I thing has to be precisely placed to accom• ral and the human-made environment strong. There were many reasons for this, wanted to be close to the tree, having it in modate manufactured materials. Building into one, when you listen to the sun and including a longing to research an un• front of my courtyard, with the entrance with earth, you can add as well as remove the wind and the natural forces all around, known material, to understand and cel• facing east, because the strong winds came material to create the shapes you desire. East ebrate its possibilities. I also wanted to find from the west. I wanted the retreat to pro• The earthbag allowed me a great deal of out what it takes for a woman with few vide a place to sit facing the courtyard and freedom. I wanted to celebrate this. As I manual skills and little strength to build the Joshua tree. worked with this totally fluid material, single-handedly a shelter for herself and When planning the retreat, I tried to earth or sand in bags, I wanted the materi• her children. I wanted to indulge in the figure out what I would like inside it, never als to lead me. I did not want to make it freedom of using earthen materials, hav• restricting my imagination. I knew that imitate another kind of building. I wanted ing learned about the structural form of people who stayed here would need a place to set the dome free, to listen to it. I was the arch, which allows the use of only for their luggage, a place to sleep, and per• building with love, creating something earthbags for the whole structure, with no haps a place for a child to sleep. So I de• that felt right. I believe that all buildings reliance upon wood. signed for a couple and their child. A fire• should be designed and built with sensi• My passion for the arch as a structural place would be used to keep warm and to tivity. To me, love has become the most form has little to do with the ways sym• cook on. Then I thought of the views, the important factor in designing. In fact, I metrical domes or vaults have been used light, sunrise and sunset, and the lookout now see that designing and building are xviii

The author (in foreground) with lliona BUILDING WITH EARTH Outram (behind) and other Cal-Earth visitors inside the Earthmother Dwelling.

the building can be an organic extension basic introduction to some other forms of of the land and the outcome of a marriage "alternative architecture." You have to un• between wind, sun, and the soul of the one derstand that this is a drop in the ocean. I who dwells there. can only introduce the concepts, sharing At the moment, my ideal house is one some of the lessons I have learned and that lives in such harmony with its envi• sights that I have seen. Numerous books ronment. It is a house that is difficult to have been written on many of the natural notice, like an animal that blends into its construction techniques, some of which surroundings. So many houses appear like can be ordered from the organizations warts in our landscape. When you drive and bookstores listed in the resource sec• through the countryside, how much nicer tion. However, to my knowledge, no one it would be if you couldn't see the houses, has written a book-length work about the if they blended in harmoniously, like the earthbag construction technique, only houses that climb the hillsides in Afghani• short articles for various magazines. This stan, made of the same earth as those hill• was my primary reason for putting pen to sides. Only at night, when the lights come paper—to provide some of the theoretical on, do you see the extent of the develop• knowledge that I gathered in the places to ments. which my research took me. That theoreti• In building my "Earthmother Dwelling cal foundation is necessary to begin con• Retreat" at Cal-Earth, these are some of the struction, but the reader must remember sensitivities that I brought to the process. that no amount of theory can teach as In this book, I will give a thorough in• much as your own hands. Happy experi• troduction to earthbag construction and a menting! 1

EARTH ARCHITECTURE

ince the earliest times, people have lived in the earth, taking up residence in existing structures or forming and sculpting Searth around them according to their needs. In terms of growth and development, indigenous communities usually lived within the limits of their ecosystems. Nature, technology, and cul• ture maintained a balance. Until the industrial revolution, most of the world's people housed themselves in earthen architecture (Khalili 1986,58). Even today, it is estimated that a third of the human population lives in houses constructed of unbaked earth. But, during the industrial age, the use of engines and fossil fuels expanded the limits of local ecosystems. Resources from distant regions were brought together in the process of mass production. Industry on an unimaginable scale transformed the landscape, while the goods manufactured on assembly lines transformed our values. Yet for a long time the environmental consequences of modern design seemed remote. At the beginning of the twentieth century, architects were inspired by machinery, not by nature. Modernists saw buildings as isolated ob• jects, not as part of larger systems or communities. The designs of Above: An afternoon snooze in the city of Petra, the industrialized world have developed to depend on materials Jordan. and technologies beyond the limits of what local ecosystems pro• vide. It may seem as if technology has given people the freedom to override the laws of nature. But if we use that freedom, we must take responsibility for making these choices. Today, our global technologies are depleting the Earth's resources, darkening the water and skies with waste, and endangering the diversity of life.

Can we find a way of life that will re-create a balance between na• Facing page: The ancient city of Petra, Jordan, carved ture, humanity, and technology? out of sandstone.

3 EARTH ARCHITECTURE 4 5

Today, timber, steel, and cement are not ing houses, the use of local materials is niques with elements of modern technol• manner: She inspires and advises her pot• readily available in many parts of the becoming increasingly important, among ogy, permit people to build dwellings that ters what to do while working with clay. world. They must be transported from many other environmental aspects. Using are appropriate for the sites and climates There is a Tewa prayer, of which the thousands of miles away. For the people local materials not only saves energy and where they are built. It is beyond the scope Santa Clara Pueblo poet and potter Nora

who live in those regions, it would make resources, it gives builders and dwellers a of this book to provide detailed descrip• Naranjo-Morse says (Swan & Swan 1996), more sense to build their own houses out sense that they are grounded, a sense of tions of each natural building technique, "This prayer continually renews our rela• of what is "beneath their feet" and to use belonging, which is missing when "for• and the books listed in the bibliography tionship to the earth, her gifts, and [the the materials within their reach. Yet in the eign" materials are used. In the southwest• provide more comprehensive information people]." less industrialized countries, where mod• ern United States, for example, the Pueblo on adobe, cob, rammed earth, straw bale, ern building materials are used by the privi• people have traditionally used adobe, a and other methods. Here I will give brief Clay Mother, leged few, poor people often look down sun-dried clay brick, because sun and clay introductions to several traditional tech• I have come to the center of your upon the ancient construction methods are easily acquired and worked with. In the niques that are especially useful in combi• adobe, and scorn the earth as a building material. northeastern United States, houses were nation with earthbag construction. feed and clothe me In response to this, some designers and traditionally made of wood, not because and in the end you will absorb me builders, including the late Egyptian ar• clay wasn't there, but because wood was CLAY-BASED into your center. chitect Hassan Fathy, have attempted to plentiful and easily available. In England, BUILDING MATERIALS However far you travel, revive ancient techniques, building earth particularly in Devon, cob was the popular A critical ingredient in durable, resilient do not go crying. houses for the poor as well as for the rich. building material, as the soil was perfect earth for building is clay. In response to Earth has been used to build on moun• for forming the loaf-shaped lumps that cultural, climatic, and geographical differ• Clay is the result of the chemical weath• tains, cliffs, marshlands, and the harshest constitute the basic building block in this ences throughout the world, many varia• ering of rock and silicates such as feldspar, of deserts. With a suitable mix of ingredi• method. Sadly, people have almost stopped tions of clay-based earth architecture have quartz, and mica. The diameter of clay ents and appropriate design, earth can be building earth houses in England, now been developed. These techniques can be grains is smaller than two one-thou• used to build almost anywhere in the that bricks and concrete are cheap and traced back thousands of years; for ex• sandths of a millimeter. There are several world. Why not continue to use earth and available. ample, traces of mud walls from more types of clay, but the most commonly other natural materials where it is appro• In the United States today, builders are than two thousand years ago were found at found are kaolin and montmorillonite. priate to do so? gradually returning to older and more the Tel Dor excavations in Israel (Stern With an electron microscope, one can see One of the reasons for the revival of natural construction techniques. People 1994) 133). Parts of the Great Wall of China that these materials are wafer-thin, foli• earth architecture and for the sudden rise are learning from ancient European earth- are built out of earth and are still standing ated, and scaly crystals. of interest in alternative ways of building is building traditions such as cob and wattle today. In many cultures, clay has long been Earth alone (without the use of forms) the change in people's level of conscious• and daub, as well as from the traditions of considered a magical material. It is written can be used for construction only if it con• ness. A growing movement to promote the Pueblo Indians adapted from the in holy books and poems that humans tains some kind of stabilizing element, "natural," "environmental," "sustainable" straw-clay adobe building technique that themselves were created from clay. which in industrialized architecture is of• understanding is now trying to make was brought by the Spanish a few centuries In the Pueblo cultures of the American ten cement. In traditional natural build• people aware of the devastation that we ago. New methods, such as straw bale and Southwest, one of the deities is the Pueblo ing, we use clay as the binding material, have caused on our planet. Among those earthbag construction, which combine the Clay Lady, who is said to live in each piece due to the cohesive properties of the clay designers and builders involved in build• benefits of a variety of traditional tech- of clay pottery made in the traditional molecules. These molecules are attracted 6 EARTH ARCHITECTURE 7

to each other, therefore producing a strong popular as a base for interior and exterior it is very inexpensive to build with adobe if bond. If clay particles are well distributed plasters and construction materials. This you do the work yourself. throughout the soil, they form a coating is largely due to cost and energy savings, The Taos Indians of New Mexico have a around the particles of silt, sand, straw, and to the way that houses built with clay- long tradition of earth building using and gravel or other filler used, effectively based materials are more aesthetically adobe. Adobe houses are part of the cul• binding them together. pleasing and healthier to live in, especially ture of the Pueblo people. They go to• On drying, the swollen clay shrinks un• for chemically sensitive individuals. gether like Eskimos and igloos. During the evenly and causes shrinkage cracks. The See chapter 7 for more detailed infor• persecutions by the Spanish and by the more water that is absorbed by the clay, the mation about working with clay as a build• Americans the adobe walls protected the larger the cracks will be after drying. Each ing material. Pueblo people and allowed them to keep type of clay has a different chemical com• many of their spiritual beliefs, attitudes, positions, but above all they vary in their ADOBE and practices to themselves. water-absorbing qualities. Kaolin absorbs Adobe blocks are sun-dried mud bricks The beauty of earth architecture is that water the least, while montmorillonite can that can be stuck together with mud mor• it participates in the natural environment. absorb seven times as much water, and can tar to create thick walls. They have been It is part of a continuous cycle, unlike con• swell to sixteen times its volume. Working used for thousands of years in North Af• temporary industrialized architecture, the clay with your hands enables the clay rica, South America, Asia, and the Middle where structures are built to stand inde• particles to pack together in denser, paral• East, and were brought into the southwest• pendent of and unaffected by their sur• lel layers, creating stronger binding force. ern United States by the Spanish. The roundings. Build, live and die, build, live... Adobe houses in Taos Pueblo, New Mexico. As a result, the tensile and compressive Spanish learned about adobe construction Adobe houses, like other earth houses, strength is greater, up to 20 percent more from the Egyptians, who still use this an• have to be cared for continuously and or adobe houses to live on we have to take care of them, like than in mechanically compressed blocks. cient building technique. Using the arch, when their useful life is over, they are given you would take care of a child. You coat the child, we plaster dome, and vault, it became possible to cre• Many different types of traditional earth the respect of being allowed to melt back the adobe houses, so they can stand up. When you live in a construction require some clay as the ate houses using only earth (Fathy 1986). into the earth. For example, a house is house the house is almost like a part of you because you live in it and binder for cohesion, including adobe, cob, Many magnificent large adobe structures boarded up after the death of its owner. it lives with you. When you keep the house warm it will keep you rammed earth, wattle and daub, and are still in use in Africa, Asia, and the New people moving in will mold new ado• warm. If you die the house will also die with you. When you build a blends of clay with straw or other fibers. Middle East. bes from the material remaining, and the house, you build the house with what you're actually standing on. Because of serious, building-related envi• While in most of the world's countries cycle will continue. Once upon a time there might have been a house there also, but the ronmental problems in industrialized adobe is used for the poor, in the south• Adobe structures flow out of the earth, recycling of the adobe material is almost like building what had been countries, in recent years we have seen a western United States it is increasingly and it is often difficult to see where the there once upon a time.

dramatic revival of traditional building fashionable with the very rich to live in a ground stops and the buildings begin. By —Joe Martinez, Taos Pueblo, techniques based on clay. Clay is non• healthy, natural house. Because adobe is using adobe to build the walls of a house quoted in At Home with Mother Earth toxic, recyclable, and easily available in very labor intensive, it is very expensive to and cob to sculpt the interior, beautiful, (Feat of Clay, 1995) many parts of the world. Combined with pay someone else to build and finish an curved forms can be fairly quickly con• sand, gravel, and natural fibers such as adobe house. But, because the materials— structed that provide very inviting living straw and wood, clay is again becoming the earth at your feet—are practically free, space while also providing the mass EARTH ARCHITECTURE 8 9

needed for a building to perform well thermally. Ovens and seat• earth structure can be made if a minimum ing as well as walls can be created using adobe finished with an of 5 percent clay is present to bind the soil earthen plaster. (See chapter 7 for more discussion of how to use and if wood or other material is available adobe in conjunction with other earthen techniques.) to make temporary forms. The traditional method of adobe preparation is a highly labori• Rammed earth is another ancient Cob fireplace sculpted ous process. The strength and durability of the finished dwelling earth-building technique currently being by Kiko Denzer at the depends upon the quality of the bricks. Adobe bricks are produced revived in many parts of the world. The Black Range Lodge, Kingston, New Mexico. by putting the appropriate soil, clay, and straw mixture into a mold Great Wall of China is partially built out of where the mix is worked lightly by hand then quickly removed. The Adobe house of Hassan Fathy, Egypt. rammed earth, and this technique has mold must be clean and wet to ease removal of the formed brick. been used in Yemen to build structures as Adobes can also be made without forms, but a large quantity of high as seven stories. In eighteenth- mortar must be used to smooth out the unevenness of the joints. century France, a pioneering architect Adobe is sometimes criticized for being a very soft material, but named Francois Cointeraux tried to revive adobe construction is a system. That is, no single brick is subjected graded subsoil mixed with plenty of straw rammed earth construction with little to intensive pressure, because the overall wall, which is stronger requires no other additives to make good success due to fear of competition among than its individual parts, carries the weight of the roof. To add to its cob for building. other builders. Currently in France, the strength, adobe can be reinforced with a diversity of fibers. The durability of a cob house depends use of earth as a building material is being on how much energy is put into it as well as revived by the organization CRATerre. In COB what is in the mix. If a cob walls fails it is Cob is like an adobe mix with as much straw as the mud mixture usually not the fault of the material but of can accept before it fails to bind. That is, subsoil containing clay is the builder. Like adobe houses, if the cob mixed with straw and water and brought to a suitable consistency house is loved and cared for it will last for A boy making adobes in Peru. by kneading or treading. The lumps of earth (or "cobs") are then a long time. placed in horizontal layers to form a mass wall. The bulk of a cob structure does not always consist solely of cob mixture. Cob that RAMMED EARTH contains gravel or rubble can be sculpted into walls, making the This is another age-old technique that uti• whole structure more resistant to moisture, allowing more air to lizes only the earth to create thick, durable circulate inside, and keeping it drier. walls, which can be load-bearing, low-cost, Cob was traditionally a popular building material in the west• heat-storing, and recyclable. Rammed earth ern parts of Britain, mostly Devon and the southwestern regions, structures can be built in a variety of cli• because the soils of that region are among the best in Britain for mates and will last for hundreds of years. earth construction. Most soils there contain a good proportion of The construction procedure is simple. A clays that are fairly coarse and therefore do not expand and con• mixture of earth is rammed between tract extensively and which provide adequate cohesion. Secondly, wooden forms. The forms are removed, these soils are usually found to contain a well-distributed range of creating thick walls that need no external aggregates, from coarse gravel to fine sands and silts. A good, well- finishes. The most basic type of rammed Rammed earth house in Arizona. EARTH ARCHITECTURE 11

Australia, it is a popular alternative build• earthbag wall. Other combinations of fi• ing technique, and its modern application Advantages of Adding Fiber ber, clay, and sand are probably being de• in the United States has been pioneered by Some of the many advantages of adding veloped, as the possibilities are endless. See David Easton, who updated Cointeraux's fibers such as straw to an earthen mix are: chapter 7 for more detailed discussion of techniques with improved engineering, straw-clay mixtures. • controlling the shrinkage cracks sophisticated forms, and innovative design Earthen materials and natural fibers • increasing tensile strength to make rammed earth cost-competitive • improving insulation value work together extremely well, preserving with conventional construction. Modern and protecting one another, and combin• A wattle panel under construction. equipment speeds the process. The soil is There are also many advantages of coating ing the earth's thermal mass with the mixed on-site and then poured into the natural fibers with earth: fiber's insulative value. Bill and Athena wooden forms set up on top of an appro• clay and straw. When dry, the surface can • increasing compressive strength Steen, who have been using straw-clay priate foundation (usually stone or con• be plastered with a mixture of lime, sand, • providing fire resistance techniques in Mexico, have said "they can crete). An earth mixture with a moisture and animal hair and painted with white• • improving water resistance be built from predominantly local materi• content of 10 percent is then rammed in 6- wash. Chapter 6 describes lime plasters • improving insect resistance als in whatever combination best matches to 8-inch layers using pneumatic or hand and finishes for use on any earthen wall. the local climate. Like the rest of life, build• tampers. The forms are removed, reveal• ing can be much more fulfilling when ing a 2-foot-thick wall that is then com• STRAW-CLAY founded on a good relationship. For us, plete. A concrete bond beam is poured for Straw-clay is the general term used for any ... combining earth with natural fibers has Straw-clay block the top of the wall on which the roof will building material that is made out of straw led to an unfolding of options and possi• construction of the sit. Even at its simplest, rammed earth re• and clay (with some sand to reduce crack• bilities that would not be open to us if we office headquarters for quires more complex technology than ing and increase mass) but does not fit into were to remain simply straw bale builders." the Save the Children Foundation in Cuidad adobe or cob but can be used to raise mas• the traditional adobe or cob category. Al• The main disadvantage of adding fiber Obregon,Mexico. sive walls in a shorter period of time though the mixture can be very similar to to an earthen mix is the reduction in the Straw-clay can be used (Easton 1996). adobe or cob, the main difference is the to make large blocks to material's thermal properties. The more construct whole walls, greater quantities of fiber. If the binding straw, the less thermal mass the structure wall or ceiling infill WATTLE AND DAUB clay is diluted with more water to a creamy will have. This is only a disadvantage if the between framing or floors, large ceiling liquid consistency prior to mixing with fi• surface is needed for passive solar heat gain In Britain, wattle and daub was widely panels made by used in the construction of internal walls bers, it becomes "light clay." The most or cooling, in which case less straw and inserting bamboo or and ceilings and also for external walls of popular uses of straw-clay mixes include more sand can be added to the mixture. branches as reinforcement, or even houses. Wattle-and-daub panels in tim• straw-clay blocks (straw coated with light rolls and arches. ber-framed houses were in common use clay rammed into formwork), thin interior PAPERCRETE until the eighteenth century. or exterior walls reinforced with bamboo "Papercrete," or "fibrous cement," is an ex• The wattle (branches) act as support for or branches, ceiling infill between beams perimental technique recently reinvented mud plaster (daub). Oak or other timber or floors, or straw-clay panels for thermal independently and pioneered by Mike or acoustic insulation. Higher density of stakes are installed vertically into a frame McCain in Alamosa, Colorado, and Eric straw allows for better insulation for roofs, woven out of willows or other flexible Patterson of Silver City, New Mexico. floors, or the insulating layer on an wood and covered with a heavy mixture of Papercrete is a type of industrial-strength EARTH ARCHITECTURE 12

papier-mache used to make large blocks to 10 percent cement. This mixture is then This method of construction is rising in intensive than adobe, cob, or rammed construct houses as well as a plaster for poured into forms to make blocks and can popularity among natural and alternative earth. Earthbags can be used in areas with covering them. It has been successfully also be used as a plaster or mortar. builders, especially in the United States. limited technology and low income, but used in earthbag projects as a thick plaster. In Adobe Journal (nos. 12 & 13) Mike This technique is essentially a flexible- where people are willing to work on con• If applied in several 2-inch (50 millimeter) McCain described a procedure for making form variation of rammed earth. The bags structing buildings for themselves. The layers, papercrete will contribute to the in• large quantities of papercrete. Fill a tank are permanent forms that allow you to bags are cheap and easily transported, so sulation value of an earthbag house. Ac• with water and add magazines and news• ram or tamp the earth to create thick this technique can be used for disaster- cording to Gordon Solberg in an Earth paper. Start mixing, and when the mixture earthen walls, symmetrical arches, vaults, relief housing. Quarterly special issue on paper houses turns into a slurry, add 8 to 9½ one-gallon or domes, and freeform landscape fea• (see the bibliography), papercrete's R-value buckets 2/3 full (or 6 shovels-full, approxi• tures; and to sculpt forms the way a potter mately) of sandy soil that has been sieved molds coils of clay, blending your struc• is 2.8 per inch. When dry, papercrete is Sketch view. lightweight, holds its shape well, and is using chickenwire to eliminate larger ture into the landscape. remarkably strong. Papercrete is also du• rocks. Then add one 94-pound bag of ce• The earthbag technique requires few rable when wet, although not waterproof, ment to the mix. The amount of water skills and tools other than a shovel, and and in very damp climates will need to be needed can be estimated by watching as can be used on almost any land, in any lo• sealed with a waterproof layer. For in• the cement is absorbed by the paper fibers. cation. When built properly, earthbag stance, a coat of tar has been used success• Be sure that the water is evenly distributed walls are extremely strong. They are most Plan fully as waterproofing on top of a paper• thoughout the mix, as any excess water will advantageous in remote areas with no crete structure in Colorado. separate. By weight, 20 percent of the mix• wood for a frame and no clay for a cob or ture should be one-half sand, one-quarter To make papercrete take a large mixing adobe building, since the use of bags as a paper, and one-quarter cement, and the container and soak old newspapers and container allows the builder to utilize a remaining 80 percent of the mixture magazines until they are soft. Mix in ce• wide range of soils, from unstabilized should be water. earth or sand directly from the site to soils ment or lime and sand for greater strength. with a high clay content, or even gravel. As The recipe for the papercrete plaster mix Mike has devised a faster and easier way Interconnected spaces can be arranged in response of mixing by mounting a barrel with an a result, costly materials such as cement Kelly and Rosana used on their house (see to the site and solar exposure. and steel can largely be avoided. Earthbags chapter 8) is as follows: overturned lawnmower blade in the bot• tom above the axle of a cart. He uses a drive can even be used in areas prone to flooding and periodic wet conditions. First coat (more insulative): 1 part shaft to turn the lawnmower blade when paper to 1 part cement + water the wheels of the cart turn. The mixer can If an arch is used as the primary struc• Second coat (more waterproof): 1 part be towed behind a car or truck, or even a tural element—for example, a dome for cement to 1 part lime to 8 parts sand horse. the central structure with self-supporting + water arches for openings—no wood is neces• EARTHBAGS sary in the construction, thereby avoiding To make papercrete blocks for con• Earthbags are textile bags or tubes filled the deforestation so widespread in the struction, Gordon Solberg recommends with earth (sometimes sand or gravel), United States and around the globe. rammed to a very solid mass, then used to Earthbag buildings are low in materials mixing together a "soup" of 60 percent pa• Roof plan. per, 30 percent screened earth or sand, and construct foundations, walls, and domes. cost, but intensive in labor, albeit less labor- EARTH ARCHITECTURE 14 15

An earthbag "dome" is rounded overall, required. Such structures grow organi• raid shelters; and by landscapers, to create ersidad Francisco Marroquin in Guate• but not necessarily symmetrical. The height cally, each addition buttressing the next free-form retaining or enclosure walls. mala, which attempted to develop an of the dome proportionally exceeds its di• one. Chapter 2 explains the principles of According to J. F. Kennedy (1999, 82), earthquake-proof system. Long cotton ameter. The difference between earthbag arches, domes, and vaults that you will German architect Frei Otto experimented tubes, dipped in lime wash to prevent the domes and the high-tech geodesic domes need to know to build these structures in the 1960s with using earthbags for bags from deterioration, were filled with invented by Buckminster Fuller is that with earthbags. building. In 1978 a team from the For- volcanic earth (pumice) and stacked be• earthbag domes can never have large Through recent history, sandbags and schungslabor fur Experimentelles Bauen tween bamboo poles, serving as a proto• spans. An earthbag house can be anything earthbags have been used for varied pur• (FEB), the Research Laboratory for Ex• type for a single-story house. The poles from a single dome to a whole village of poses, mostly in emergency relief work, for perimental Building at the University of were tied with wire every fifth course and domes interconnected by vaults. Arched example to provide erosion or flood con• Kassel in Germany, led by professor, archi• fastened to the foundation below and a openings can form entrances into other trol, when filled with earth or pumped full tect, and author Gemot Minke (Lehmbau- bond beam above, creating movable but spaces, niches, and apses. If a large earth- of concrete or soil cement, then used for Handbuch, 1997), set up an experimental earthquake-resistant walls. Further re• bag house is desired, many domed struc• fast construction of embankments. Earth- earthbag project. This experiment was fol• search was carried out by Minke at the tures can be built, each one joined to the bags have also been used by archaeologists, lowed by a joint research project spon• university through extensive experiments next using a small vault. New openings can to aid in structural support of collapsing sored by the FEB, the Center for Appropri• with earth-filled sacks and tubes to create be easily cut out and extra rooms added as walls; by armies, to create bunkers and air- ate Technology (CEMAT), and the Univ- various structures, including domes.

Structural and Seismic Testing

wrap around the building rather than lifting it (Muller 1993). By contrast, vaults have a very poor etween 1993 and 1995, three of the experimental earthbag structures at Cal-Earth passed earthquake resistance. This is due to the torque oscillations in structures, caused by the strong structural tests approved by the International Conference of Building Officials (ICBO), increase in seismic accelerations transferred from the terrain to the founda• leading to a building permit for the Hesperia Museum and Nature Center in California in tions when at different levels the centers of gravity do not coincide with BMarch 1996, the first to be granted under the California Building Code for earthbag construction. the centers of torsion (Houben and Guillaud, 313). For seismic areas, A school initially designed by Nader Khalili and lliona Outram in Nevada is currently under Nader Khalili has developed a foundation system where the base of construction with code approval (Outram 1996). the dome is isolated from the slab it sits on by a layer of sand, The tests carried out for the ICBO included a live-load test and dynamic and static-loading therefore enabling the structure to move freely during an earth• tests. For some of the tests, cables were wrapped around three buildings of different designs, and quake, (see chapter 3 for more on foundations). hydraulic jacks were used to pull 3,000 pounds of cumulative pressure every 15 minutes. Nader

Khalili explains, "On our superadobe prototype we went from 3,000 to 26,000 pounds of continu•

ous stress and held it there for hours. This was beyond any required code for any building within

fifty miles. The inspectors found no cracks or movement, so now this method is approved for all Above: In 1993 the sandbag and barbed wire system was analyzed at Cal-Polytech, San Luis Obispo, where testing included observations on a scale model on a seismic table (Outram 1996,58). The earthbag structures types of buildings, from residential to commercial." (designer/builder June 1996.) tested were constructed out of unstabilized earth, with barbed wire between each course, an adobe plaster In high wind and earthquake areas, symmetrical buildings tend to be less heavily damaged. finish inside and outside, and metal strapping loosely netted about the structure to contain bursting forces. The The form of a dome is more likely to absorb an earthquake's jolts and spread the shock equally intersections were riveted or bolted together, and four zones of diagonal "X" strapping were added for through the structure, and the weight and curve of a dome deflects winds, allowing them to resistance to shear forces (Kennedy 1994, 19). 16 EARTH ARCHITECTURE 17

The recent trend in using earthbag tech• Kaki Hunter and Doni Kiffmeyer of OK rial (meaning it contains little binding work can be hacked off, exposing the bags. nology in building homes is largely due to OK OK Productions; a three-vault house strength such as clay) the stronger the bag Cut the bags with scissors or a scalpel, and the pioneering work carried out by the built by Cal-Earth apprentices in Sar- material must be. If the soil has a high clay scoop out the hard, rammed earth. The Californian Institute of Earth miento, Mexico; a development built by content, bags might not be necessary to bags can then be resealed using nails like Art and Architecture (Cal- Mara Cranic in Baja California; a two- contain the earthen mixture (see the dis• tailor pins or sewn together with wire, and Earth) in the Mojave Desert, story house, the ground floor constructed cussion of soil testing in chapter 7). In that the plaster reapplied. This is a time-con• which was set up by Nader of earthbags and the first floor of timber, case, other construction techniques such suming process, and care must be taken Khalili, Iranian-born architect built in the Bahamas by Carol Escott and as adobe or cob might be more appropri• that the opening cut out is in the shape of and author, who calls his build• Steve Kemble of Sustainable Systems Sup• ate. When earthbags are used, especially in a steep arch for structural stability (see the ing technique "Superadobe." port; a hybrid earthbag and pumice-filled- flood areas, care must be taken that the discussion of openings in chapter 4). If a Since 1990, the team at Cal- bag house built by Kelly and Rosana Hart lower courses of the wall do not contain square opening is cut out, the opening will Earth, in collaboration with of HartWorks; and Joseph Kennedy's ex• clay, which wicks moisture. If the higher not support rows of bags above. Square the city of Hesperia and many perimental work in South Africa with bags courses contain clay, they need to be openings must therefore be the height of researchers and associates, has containing high proportions of clay, ce• tamped or rammed well to reduce the like• the whole wall. Better yet, plan ahead and been investigating earthbag ment bond beams, and bag additions to lihood that insufficiently compacted clay build in arched openings that can be ac• construction and developing existing structures. will absorb moisture. cessed later by removing the finish plaster. its applications, from straight Earthbags are also becoming popular The cheapest and most flexible option is to walls to domed structures. To among natural builders as foundations, EXTENDING OR RECYCLING THE plan future extensions at the outset. Do satisfy a desire (or even an ob• filled with gravel, sand, and/or earth, be• BUILDING not be afraid to start small and expand session) to avoid wood, they neath straw bale and cob buildings. Earth- It is helpful to plan for future extensions of later. An experimental dome have managed to create stable dome- bag structures can range from emergency an earthbag building during the initial de• An earthbag structure can also be com• at Cal-Earth, has stood for five years without shaped structures using the corbeling refugee housing for the poor to elaborate, sign stage in order to prevent awkward re• pletely recycled. If the bags were filled with interior plaster. Though method (see chapter 2). This means that modern residences complete with plumb• design problems later and to avoid the pure earth from the land the building is the polypropylene with no materials other than bags, barbed ing and electricity. need to rethink all the openings and utili• standing on, once the structure is no bags have degraded wire, and local earth, you can build your• ties. For example, anticipating a future from ultraviolet light, longer maintained the walls will begin to the compacted earth, self a shelter anywhere in the world. WHEN ARE EARTHBAGS opening by building an arch in that loca• turn back into earth after a few decades, which has a low clay Many people who have attended work• APPROPRIATE? tion and filling it in with nonstructural especially if biodegradable burlap bags content, is falling apart earthbags or another material such as were used. If polypropylene bags are used, as could be expected. shops at Cal-Earth have started to spread The bags are used only as a temporary their knowledge. The first fully function• formwork for ramming the earth, before straw bales or straw-clay mixture can save they will only biodegrade if exposed to the ing and lived-in earthbag dome was built the plaster is applied. It is actually the plas• much time when you decide to cut sun's ultraviolet light once the protective in Arizona for Shirley Tassencourt by ter that should be considered a permanent through the original wall to make an addi• earthen plaster deteriorates, which it will Dominic Howes, who went on to build enclosure or casing. The materials used to tion. But if the earth in the bags is do over time without regular recoatings. If other round, domed, and straight-walled fill the bags can range from very loose compactable and not just pure sand, an earthbag structure is dismantled prior or square earthbag houses and water-stor• gravel, pumice, or sand to a more com- which will simply spill out when the wall is to the polypropylene's disintegration, the age tanks. Many others have followed, in• pactable soil, which might contain varying breached, it is also possible to make open• bags as well as the earth inside can be re• cluding a domed structure built in Utah by amounts of clay. The weaker the fill mate- ings later if really necessary. The plaster- used for a new building. EARTH ARCHITECTURE 19 18

the shelter is needed only for a year or two, EARTHBAGS FOREVER in which case the bags can be left exposed TLHOLEGO LEARNING CENTRE, SOUTH AFRICA Many regions in the world, including the and allowed to deteriorate in the sun. desert regions of North Africa, the Middle Another great advantage is that sand• his prototype was designed by East, and the southwestern United States, bags have long been used to control floods Joseph F. Kennedy and constructed do not have abundant supplies of wood, and erosion in many areas. This demon• using burlap sacks and soil-cement stone, or clay. In Egypt, for example, the strates the strength and durability of these Tplaster, a concrete bond beam, and a brick traditional construction material was walls, suggesting that this material would dome roof. adobe made out of clay taken from the be perfect for flood areas and disaster re• The walls were built using burlap sacks flood plains of the Nile. Now clay is in lief. The aerodynamic shape of domed filled with the earth from the site, which great demand, and therefore more expen• houses that integrate into the landscape, had a high clay content. These were well sive to acquire. To be able to build with or• shaped like mounds or hills, might better tamped to achieve compaction. The bond dinary sand or unstabilized earth could withstand strong winds and hurricanes, beam was poured on top of the wall to

which the brick dome would be fixed. The benefit many people. providing another advantage of these in•

first row of bricks to the brick dome was Of course, unlike adobe or cob con• expensive shelters. hollow, allowing the insertion of reinforcing struction, where the earth used contains Ultimately, my love for the earthbag rods and anchor bolts to anchor the dome clay as a binding element, the sandbag or technique also comes from the simplicity to the bond beam. The structure has earthbag technique requires a source of of the construction process. There is no Detail of the earthbag house prototype showing the brick domed roof and buttresses. buttresses for added stability and was bags, but in most places, cloth is an acces• saw or nails in sight, just bags and earth. plastered with soil cement. Sawn bags were sible commodity. These bags can be made There is no need to lift heavy loads, be• also used for shade on the trellis. out of absolutely any cloth, even old cause the earth is carried to fill the bags in clothes cut up and modified to hold earth. place. Any child or adult could build them• The bags are only there to hold the earth in selves a house! place before plaster can be applied, unless

External planters, also constructed using earthbags. 2

USING BASIC STRUCTURES FROM NATURE

TO BUILD WITH EARTH

o be able to build out of earth When you consider the size of an alone, we must understand certain individual termite, photographed Tbasic structural principles. To me, standing alongside his nest, he ranks the most important structural element, with the New Yorker and shows a Facing page: The first the key to all earth construction, is the better sense of organization then a earthbag dome attempted at Cal-Earth. resident of Los Angeles. Some of the arch. This was one of my earliest and most Strapped straw-filled exciting discoveries concerning earth ar• mound nests of Macrotermes bags form the upper chitecture, as the arch is a form that occurs bellicosus in Africa, measure twelve part of the dome. all around us in nature, which allows us to feet high and a hundred feet across, build strong, resilient structures without [and] contain several millions of high-embodied-energy materials such as termites.... The interiors of the timber, concrete, or steel. An arch can be nests are like a three-dimensional used to form the curved or pointed upper maze, intricate arrangements of end of an opening (as in a window or door) spiraling galleries, corridors, and or a support (as in a truss or bridge); this arched vaults, ventilated and air shape is strong and stable because gravity conditioned.... The fundamental pulls equally on each part, and each part structural unit, on which the whole supports the weight of the parts above. design is based is the arch. Termites building an arch. Even though they Most naturally occurring caves incor• work on the opposite porate the arch in their structure. Also, As Nader Khalili has noted in Ceramic ends, the arch meets in animals that make dwellings in the earth Houses, forms in nature, whether con• the center. (After Woodward 1995.) use this form to prevent their homes from structed or created by natural forces, ex• collapsing. One such example is a colony emplify efficiency. of termites building their earth house us• ing the arch as their main structural ele• Nature generates structures based on ment to support a network of ducts and the principle of minimum material, cavities, as described by Lewis Thomas in maximum efficiency. From mol• The Lives of a Cell: ecules, to soap bubbles ... all follow

21 USING BASIC STRUCTURES FROM NATURE TO BUILD WITH EARTH 22 23

this general rule ... a spider's web is a natural structure that vides ideal compression, evenly distribut• horizontal pressure is the point along the works by ultimate tension, and an eggshell is a structure that ing the downward, compressive forces arm of the arch where it begins to curve works by ultimate compression. Both use the minimum and along the whole of the arch. toward the center to meet its symmetrical the appropriate material with maximum efficiency. counterpart, the other arm of the arch. The imaginary line running between these Over the course of architectural history, the construction of two points where the curves commence is roofs and openings out of earth alone became a necessity in many called the spring line. Buttresses should re• regions where structural timber was not easily available. In Egypt inforce the base of the arch up to this and the Middle East, among many other places, builders came up A chain under tension. Chain turned upside down spring line or higher. with the idea (no doubt emulating nature) of arched openings and forms a lancet arch under compression. You can calculate the size of the buttress vaulted roofs to cover the spaces they wanted to inhabit. One can In a masonry arch using this form, the needed by drawing a model to scale on still visit large spanned domes (a set of arches with a common cen• individual bricks are tilted upward at their paper (see the illustration below). Divide a tral peak or pivot) and vaults (a series of adjacent arches) in the outer edges, toward the center of the arch. curved arch (which could also represent a Middle East built with adobe that have lasted for centuries. How• Once a keystone is placed in position at the vault as well as a dome) into three equal ever, instead of building large spaces and then subdividing them, it peak of the arch, vertical force, or gravity, tangential parts. Project out from Y, using is often more appropriate in earth construction to build several pushes down, causing the stones to press point X as the center line of a circle and Y smaller spaces connected to each other, in order to provide for against each other and transferring the as the end of the radius. Measure from structural stability in each element, and to accommodate different load to the ground. point Z to determine the necessary thick• functions, like rooms in a conventional Western building. To prevent this downward force from ness of the buttress. This introduction to nature-based architectural forms will causing the sides of the arch to kick out emphasize the primacy of the arch, that singular structural ele• horizontally, thereby collapsing the arch, ment that enables builders to construct arched openings, vaults, buttressing must be added at either side and domes. Once you understand the structural principles of the around the base. The point of greatest arch, you can create a network of variously sized and shaped Sean relaxing in the opening of Allegra's earthbag arches constellated together to form a variety of useful and beau• garden wall after a hard day of plastering. tiful spatial structures. When the arched form is repeated in linear How to determine the fashion, it becomes a vault. When an arch is rotated on its central minimum size of a buttress. axis or centerpoint, it becomes a dome. When an arch is laid upon the ground, then partially raised, diagonal to the ground, it be• comes an apse. Because successive arches function as Vertical forces acting on an arch. buttressing, in older buildings the arch is ARCHES often repeated to form vaults, serving as a A chain hanging between two posts creates an arch form that is structural and decorative element, as can Horizontal forces perfectly in tension, because of equal distribution of gravity along acting on an arch be seen in old churches and cathedrals. the curves. An arch of this shape is called a lancet or catenary arch. Other commonly used buttresses are solid Another arch acting as When you turn this shape upside down, you get a design that pro- buttresses, parapet-tie wall buttresses, and a form of buttress. Large-span concrete arch, Arcosanti, Arizona. 24 USING BASIC STRUCTURES FROM NATURE TO BUILD WITH EARTH 25

tie bars. These buttressing systems must be ing adjacent domed or vaulted structures. evenly distributed along the vault and se• In Iran, where earthen architecture is an curely anchored in the ground. ancient and ongoing tradition, the most commonly found span (or width) of vault Detail of the MAKING THE ARCH is approximately 12 feet (3.6 meters). Ac• permanent When learning about the forces of the arch cording to research conducted by the Uni• form used in Obregon, solid buttress parapet tie wall tie bars and the materials that you are working versity of Baja California, Mexico, the ratio Mexico. with, there is no substitute for actually of span to length in a vault should be no learning through your hands. You can make a small dry-pack arch as an experi• above). This form was constructed out of a mental exercise. This technique is called bamboolike reed called carrizo, which was "dry pack" because no mortar is necessary bent over a very simple temporary form to hold the arch together. A temporary and buttressed at the ends with a concrete supporting form can be made out of ply• beam. Three layers of carrizo were placed

wood, a bucket, or anything else that has a A repeated arch forms a vault. over each other and were finished with an circular shape. Balance this form on insulative straw-clay mix, capped with a wedges to ease its removal once the arch is more than 1.5 meters times the width. If a waterproof coating of lime. constructed. vault is greater in length, there is a danger Another example that I have come As you position stones or bricks on top that in an earthquake the vault will reso• across of a permanent form for vault con• of the form, place shims (small stones or nate beyond its capacity to absorb the struction was in the Hermosillo project fired brick) between the outside edges to shock, and will shatter (Khalili 1986, 57). (described in detail on page 143). Rein• ensure that the inside edge of each brick is Because the walls of a vault are structural, forcement rods were embedded in the perpendicular to the arch form. Pour sand openings such as windows and doors ground at 18-inch (450 millimeter) inter• between the bricks to fill any cavities. should be kept to a minimum. vals, then bent into position, and horizon• Once the keystone is in position at the There are three main methods for con• tal members were added. An expomat apex or meeting point on top, and the arch structing a vault. mesh—a stretchy metal mesh material is buttressed, the temporary form can be The first is to build over a form, which that can be used on corners, damp-proof removed. can be removed and reused. This is eco• membranes, or any areas where plaster nomical for small spans, but the cost of must be applied to a nonstick surface— VAULTS timber to construct the form for a larger was then fixed to the underside to hold the If you elongate an arch or repeat it in a lin• span may be considerable, unless you have 4 inches (100 millimeters) of soil-lime or ear sequence, the new form created is a a plentiful local source. soil-cement that was applied on top. This vault. The same buttressing rules apply to The second method is to use a perma• formed a very sturdy structure. The pho• vaults as to arches (see page 23). A vault is nent form, built to become an integral part tographs on page 146 show the strength of simply a deep or extended arch. Vaults can of the structure. A good example of this is the arch. The reinforcement bars alone, Construction of a dry-pack arch at Cal-Earth during construction of the Hesperia be used to form the passageways connect- in the Obregon project in Mexico (see when bent in an arched shape, could Nature Museum. USING BASIC STRUCTURES FROM NATURE TO BUILD WITH EARTH 26 27

support the weight of a person. Of course, As with arches, the buttressing for a the materials were not entirely ecological. dome only needs to provide support up to The third method of making a vault is the spring line. The buttress can either be to use no fabricated form, merely earth. constructed along the outside, or the dome The Nubian vault may be built without can be sunken into the ground so that the ground itself will act as the buttress. any structural members or formwork, just An angled masonry arch or dome. A corbeled arch or dome. using earth-clay-straw blocks or masonry (Houben & Guilland 1994). The end wall is built up first. This wall is sive horizontal courses. This is the principal used in sandbag con• either straight or arched. The first brick is struction; because the bags have no mortar to bind them and the laid at an angle, and others follow suit. The sand is a fluid form, they cannot be placed at an angle. An earthbag vault can be started at either or both ends dome could be constructed with the earthbags at an angle if there simultaneously to meet in the middle. For were a form underneath, but for a dome this could be very expen• A tension ring. A compression ring. A spiral corbeled brick dome under construction at an in-depth account of this method, see sive to construct, given the amount of material required; therefore, Cal-Earth under Nader Khalili's supervision. Note: A tension ring can be created out of concrete angling is only practical when constructing arches. Earthbag Nader Khalili's Ceramic Houses. with continuous reinforcement (rebar) at the base of the dome. A compression ring at the top is domes must be corbeled. APSES necessary only if there is an opening. To build an earthen dome on top of a square-shaped structure, An apse is a leaning arch. Figuratively, if squinches need to be constructed first. A squinch forms the transi• you lay an arch on the ground and raise it tion from square into circle. Any shape with even sides could have at an angle, it becomes an apse. Old cathe• a dome constructed above. A square is turned into a circle by cre• drals utilized the apse form for rounded ating four squinches in the four corners. In this way, a dome can extensions to the central structure, used as serve as a substitute for a conventional truss or rafter structure.

more intimate chapels or sanctuaries. The ground acting as a buttress and a buttressed Once you understand the "arch principle," there is no limit to dome. the shapes that you can create, and there is no need to be bound by DOMES the conventions of rectangular architecture or even by symmetry. A dome is an arch that has been rotated on its central axis to create a group of arches CORBELING with a common peak or center point. An alternative to the dry-pack arch dis• As already noted, because of the hori• cussed on page 24 is the corbeled arch. Cor• To Determine Thickness of a Shell:*

zontal forces tending to push the base of beling involves constructing the arch in Radius the dome outward, a buttress or continu• such a way that the units (bricks, stones, < 500 Thickness ous tension ring is necessary at the base of earthbags) lay flat, but each is stepped in•

a dome. If an opening is made at the top, ward so that the weight is evenly distrib• Radius of dome divided by the thickness of the shell should not the horizontal forces will be pressing in• uted along the arc of the arch, as shown exceed 500. ward, therefore requiring a compression opposite. ring, to prevent the structure from com• Like the corbeled arch, corbeled domes * From Philip Vittone."Dome and Vault Engineering," Adobe Journal 12 & 13 (1997): 56. pressing, or caving in. are erected by building inward on succes- 3

GETTING STARTED: DESIGN, SITING, AND FOUNDATIONS

hatever materials are used, range of your own skills. You will also gain there is no single "right" way a sense of self-reliance by learning your W to design a house, as land• way through the process. scapes differ, climates differ, cultures dif• fer, and the needs of residents differ. Before Locating the Building on the Land finalizing any decisions, research all the Whatever type of structure you want to options that are available to you. One way build, however large or small, it is impor• of doing this is to take the conceptual de• tant to place it in the context of its sur• sign to a very detailed stage to actually roundings so that it belongs to the land, as gauge what materials will be needed and an integral part of the landscape. Spend as how the various elements will go together. much time as possible on your intended Design is a process of asking yourself ques• site, preferably during all four seasons, tions, which requires knowing what ques• observing where the sun rises and sets, the tions to ask. direction of the wind, the views. Consider the neighbors, and the simplest routes for DESIGN CONSIDERATIONS access, snow removal, power, water, and Before looking carefully at site preparation sewage. and foundations specific to earthbag con• As much as possible, work around ex• struction, let us consider the basic design isting elements of the landscape such as considerations that pertain to any kind of trees and boulders. Try to minimize the construction, emphasizing the value of damage that you will inflict on the land Facing page: Apse and dome of the Hart's doing as much of the design as possible by with even the smallest of houses. Plan to pumice-bag house in yourself. By carrying out the design your• replace any vegetation that you cannot Colorado. self or in close collaboration with some• avoid destroying. Try to retain the "spirit" one who is more experienced, you can of the place, which is the result of this maintain control of the materials, keeping locale's unique qualities and features. You construction costs to a minimum and the might want to leave the most distinctive complexity of the construction within the areas of your land completely untouched,

29 DESIGN, SITING, AND FOUNDATIONS 30 31

so they retain their natural beauty and you kitchen. If you are building with earth, you what happens on neighboring sites during patios in the summer that will be exposed can enjoy them outside the sphere of your can sculpt retaining walls, benches, a bread heavy rains. Talk to your neighbors about in winter to let the sun's rays reach your house. Good design will help you mini• oven, or a grotto for gathering out of the weather patterns and their experiences on home. Deciduous trees planted on the mize your impact on the land, to satisfy same earthen materials used to construct the land. east, south, and west will provide shade in both the human occupants and the wild• the house. Creating bridges between out• Building on a hilltop increases the po• the summer but drop their leaves in the life, ideally enhancing rather than disrupt• side and inside is a crucial part of building tential for erosion. Consider wind expo• winter, allowing more sunlight to reach ing the natural energy flows in the sur• the house. sure and the aesthetic consequence for the house. roundings, creating balance and harmony. your neighbors' view if you build on a Carefully consider the materials of the Topography high, exposed site. Show the same respect building's interior. Earth or stone walls on Landscaping Go to your local building department to to your neighbors that you would like which the sun's rays fall can absorb and The landscaping around your house is just obtain historical flood reports and other them to show for you. Remember, from store heat in order to give it back at night. as important as the design of your house. information regarding your land. Choose nature's point of view, most of the time the Such walls have thermal mass, which evens Locate the house in such a way that sun• a higher location that is protected from best house is no house. out temperature fluctuations, retaining light to your flower or vegetable garden is runoff during heavy rains, or build ap• Sandbags are very often used in flooded the night's cool to keep rooms cooler dur• not blocked by any part of the building. To propriate drainage, contour swells, retain• areas, and the same technology is viable in ing the following day, and retaining day• be sure that the garden is accessible and ing walls, or gabions to rechannel runoff a house, where instead of merely using the time heat to keep a home warmer even on inviting, create an easy path to it from your around the site to planted areas. Observe bags as a barrier to water, they can be used cool nights. Earthen walls can be beneficial for constructing a flood-resistant founda• in either hot or cold climates. tion or first story (see diagrams on facing

page.) summer

Building in Flood-Prone Areas Orientation An earthbag dome for flood areas. If your land has a history of flooding and you plan to build Bags below flood level are filled Consider the location of all windows in using earthbags, you could build your house in such a way with gravel to prevent capillary relation to the sun—where it rises and sets, that the main living area is on a higher level, with the rise of moisture. Note also the winter and summer angles, and the lower level providing a foundation of bags filled with the waterproof layer shade cast at different times of year by sur• Orientation of the permeable gravel or perhaps an earthbag basement separating the lower from house toward the the upper courses. rounding hills, trees, or other existing or with good drainage for runoff. To prevent wicking south provides passive potential buildings. If you live in an area solar heating in the of moisture from lower to upper sections of winter. Overhangs limit the walls when water is standing in the that is sunny but has cold winters, adopt a solar gain in summer. lower part of the house, the walls should passive solar design to take advantage of damp-proof course incorporate a moisture barrier to the winter sun. Especially in cold climates,

separate the solid-packed avoid building on dark, damp northern flood level earthbags above from slopes. (See the bibliography for recom• If you live in a cooler area, you will want those containing gravel to mended books explaining the principles of to shield your house from cold winds. This facilitate drainage. passive solar siting, design, and materials.) can be done by positioning the building Use seasonal screens to create covered below a hilltop or behind dense trees and DESIGN, SITING, AND FOUNDATIONS 32 33

by landscaping so that foliage or other bar• to live "off the grid," providing your own Think of all the activities that might be riers provide protection. Locating a mini• electricity, heating and cooling, and hot performed inside and outside the house SITE PREPARATION: SETTING OUT mum of windows on the windward side water with solar or wind energy. With ac• during all twenty-four hours of the day, Precision in the laying out of a building's can also help considerably during those cess to a year-round stream, you may even from when you get up in the morning until base is most important for locating the windy winter days. be able to harvest hydroelectricity with a the next morning. Try to think of all the foundation in the best possible place. If If you are building in a hot and humid microturbine sized for household needs. seasonal changes in light, temperature, the earthbag foundation stem wall will be climate, it is important to position the Even in locations where the winters are smells, insects, the rain and snow, and the short and another building technique will house in the path of the prevailing breezes. cold and long and hours of daylight are views. The more time you spend on the site be used on top of this—for example, a If heavy trees block the wind's path, it is short, heat that comes free from the sun before building, the easier it will be to an• straw bale wall, a timber frame, or a roof good to raise the house and expose it to can result in significant cost and energy sav• ticipate its changes. Effective design pro• type such as a vaulted, flat, or pitched roof the breeze, with openings that go right ings. As emphasized above, a well-designed cess involves imagining the countless func• that relies on a level surface—it's essential through the house (see Steve and Carol's passive solar house can be heated almost tional and aesthetic possibilities as well as that the foundation provide a level plane. house, profiled on page 131). In the hot and entirely by solar gain with a small wood- the limitations of the materials you will be If you are building a monolithic earthbag dry climates of the Middle East, cooling burning or fossil-fuel heater as a backup. working with. structure, the foundation will be an inte• traditionally has been achieved by con• gral part of the walls and roof; therefore structing cooling towers that direct mov• Building Shape Planning Ahead the shape and size of the foundation will ing air right into the living spaces. Also Think of your house not just as a shell of a Position your house to accommodate fu• follow through the whole structure. plan for overhangs to prevent too much box or a dome, with all of its useful fea• ture additions, including outbuildings, sunlight entering the house. tures on the inside. Remember that highly without drastic modifications of the land• functional external features such as walls, scape. Also consider the ways that future porches, and benches provide sun and changes made by neighbors may affect you shade zones in summer and winter. If your over time. If there aren't any neighbors, finish will be prone to erosion from plan for the worst (a future neighbor weather, elements such as landscaping, might build a high building right against overhangs, and seasonal rain- and wind• your boundary), and you are less likely to screens are essential, as well as splash-back be disappointed. protection at the base of walls. As much as possible, it is helpful to Should the house be one large structure identify and plan your prospective exten• or a cluster of smaller ones either built si• sions of the house during the design stage Utilities multaneously or added on as the need to prevent awkward redesigning and re• At the earliest stages of planning, identify arises? A house does not have to be one construction in the future. Anticipate the the location of any existing utilities, and structure. You could start off with the need for additional services and openings. consider what services you may need in minimum living space and utilities and If you've planned ahead well, as a family the future, including a spring or well, cis• gradually add rooms, guest houses, and grows and more rooms are required, these terns for harvesting rainwater, and gray- workshops. As the family grows or your can be added with minimum cost, so do water and septic systems for processing needs change, more rooms or structures not be afraid to start small and expand wastes. In many countries, it is now viable can be incorporated. later, if necessary. DESIGN, SITING, AND FOUNDATIONS 34 35

The site should be cleared and leveled inscribing the dome, and throughout the prior to setting out lines for the founda• dome's construction. The compass can be tion and walls. If a conventional rectangu• very simple, merely a string or a chain, or lar building is to be constructed, set out more complex to serve as a guide through• string lines in the traditional manner (see out the process, allowing the builders to the diagram on page 33); at the corner maintain symmetry as the height of the points where strings cross, hammer a stake structure rises. A more detailed explana• into the ground. If the strings are placed tion of how to use a compass to maintain Two scenarios, with good and bad foundation details. On the left, lower bags are filled with gravel, which drains level with each other at a specific height, the shape in dome construction will be readily and prevents moisture from deteriorating the high-clay-content wall above. On the right, clay in the lower they can be used as a benchmark to mea• found in chapter 4, "Building with Earth- courses is worn away by rainsplash,forming cavities. sure the height of the stem wall or the bags." If organic material is removed, all of depth of the foundation trench. the subsoil taken from the foundation area building a stable base; to hold the building situations, the lower courses of earthbags earth on If you are building on a sloping site, the can be saved to fill bags. in one integral unit, especially in earth• should be filled with gravel, up to at least 12 the side) strings should be at the same height as the quake areas; and to keep the building dry, inches (30 cm) above ground level, with top of the stem wall. FOUNDATIONS providing a barrier between the walls and the upper course very level to receive fur• A circular building or a dome requires a The functions of the foundation in any any ground moisture. ther courses filled with earth or any other compass to begin construction. String lines building are to minimize any movement The connection of the wall to the material. are not appropriate for this shape. The of the ground over time; to spread the load ground is one of the most important de• When constructing an earthbag build• compass will be useful in "setting out" or of walls and roof evenly in order to give the tails on an earthen house. When con• ing in a dry area, not prone to excessive structed poorly, the wall may not last as moisture or flooding, it is best to build it long and will jeopardize the rest of the sunken into the ground. This has several Option 2 building. If the foundation is not built advantages: carefully, moisture will migrate up the wall In a dry location, buttressing is provided through capillary action and weaken the • the earth that is dug out can be used by digging a hole so earthen walls and therefore the entire for filling the bags; the building is sunken structure. • the ground acts as a buttress; into the ground. When digging the foundation trench, it • the building will sit much lower on its Excavated earth can be used for fill. is necessary to go down to undisturbed site, so it will be less obtrusive visually, ground, below the frost heave level to bed• and less exposed to severe winds and rock or compressed subsoil, to minimize weather. any movement caused by the ground. Once this solid ground is reached, you can When building above ground level, you Setting out a round base house using a string as a compass. build the foundation using gravel in a will need to provide separate buttressing. trench or in the bags, to raise the building's In damp areas, if the fill material for the A compass designed by Nader Khalili to construct base above ground level, and to prevent wall construction is high in clay content, it caternary-shaped earthbag domes for the Hesperia capillary moisture movement. In most Nature Museum. needs a foundation base with either gravel DESIGN, SITING, AND FOUNDATIONS 36 37

Foundation Details

Earthbag foundation for well-drained areas with base isolation for domes and a solid "pad" or "raft" with tension ring reinforcement. Pad can be pumice-crete, lime, or reinforced concrete. Earthbag and gravel trench foundation with damp- Gravelbag foundation for dry areas. Gravelbag foundation and buttress for domes in proof membrane for slightly damp areas. fairly dry areas with sandy soils and good drainage. (Otherwise use perforated drain in gravel trench.)

Gravelbag foundation for slightly damp areas,

without the use of Wider foundation for straight-walled house with damp-proof timber posts tied together with polypropylene or membrane. Grave] trench and gravelbag foundation. wire.

1. Exterior finish: earthen plaster, in damp climates 4. Bags filled with earth from the site, well tamped. If 7. Large stones used for a plaster stop. 11. Well-consolidated gravel, to minimize moisture capped with lime. the soil contains much clay, it needs to be more solidly 8. Well-consolidated, washed gravel in trench, to migration upward. Can be larger stones topped with compacted to minimize its"thirst"for moisture. small gravel. The best gravel is rounded to increase 2. Interior earthen plaster. prevent capillary rise of moisture. Compaction of the clay reduces its ability to draw in drainage spaces around the stones. 9. Well-compacted earthen layer. Depth varies 3. Four-poinl barbed wire or branches of a thorny moisture and consequently expand. 12. Pumice- or cement-stabilized lower course of bags, plant. This creates friction and therefore acts as a according to requirements (this layer can contain 5. Bags filled with gravel (well tamped) to raise the with a continuous ring of reinforcement in earthquake Velcro-type of mortar between the bags. Note: For radiant floor heating, but needs to be the necessary structure off the ground, to minimize moisture areas. added stabilization of straight-wall construction in thickness for effective thermal mass). migration upward into the wall through capillary 13. Drain to collect any water that may be trapped (to earthquake areas, the courses of bags can be pinned to 10. lnsulation:straw-clay mixture, pumice, or perlite- action. be approximately 1½ inches (4 centimeters) off the each other or can be buttressed or sandwiched clay mixture; depth varies according to climate. between wooden or bamboo posts tied to both the 6. Waterproofing: can consist of a layer of clay or any base of the trench to reduce blockage. foundation below and the bond beam above. other waterproofing membrane, or just well- 14. Waterproof membrane. compacted earth in very dry areas. DESIGN, SITING, AND FOUNDATIONS 38 39

or "sandy" fill. Otherwise, if the bags con• stabilized by cement, or actually with con• into an earthbag stem wall for added anchorage, and rubber tub• taining clay are exposed to water from crete, although concrete is expensive, envi• ing or metal rods can be left extending from an earthbag founda• flooding or even "splash back," the clay can ronmentally destructive, and its use un• tion to allow for compression of the adjacent bale wall. expand and break apart the wall or dissolve dermines many of the advantages of using Retaining walls can also be built with bags, but it is important to and seep out, leaving cavities and resulting the comparably inexpensive earthbags as provide good drainage behind the wall and ensure that bags are in instability. Alternatively, line the foun• an alternative. properly secured against slippage. For added stability compact the dation trench with a plastic sheet to serve To construct a foundation with insu- bags at a slight angle toward the earth bank. In addition, many as a damp-proof membrane that will pre• lative properties, you can tamp the lower other low-cost foundation systems can be combined with earth- vent moisture in the ground from migrat• bags full of scoria or pumice and wrap bag or other wall systems. Following are a few suggestions. Also, ing upwards into the wall above. Or wrap them with a damp-proof membrane, since The Last Straw magazine published a special issue on alternative each bag in the lower courses individually small-sized particles tend to absorb mois• foundations (no. 16, 1996; see the resources list). in a plastic bag before tamping it into place ture. Alternatively, the pumice can be Earth-Filled Tires (see the description of the Kaki Hunter mixed with cement to form pumice-crete. Tires rammed with and Doni Kiffmeyer project in chapter 8). For earthquake areas, Nader Khalili's This rammed earth technique is similar to earthbags but uses re• earth. If the area is not so damp, gravel in the solution was to isolate the base of the cycled tires as the permanent forms. Soil-filled tires are stacked structure by laying down a layer of sand concrete trench and gravel in the lower courses of like giant bricks to form foundations as well as exterior and inte• infill in bags will facilitate drainage, minimizing between the foundation slab or the bed• rior walls. To construct a tire foundation, dig a trench down to voids the movement of moisture upward. rock at the base of the building, allowing it frost depth, and place tires, ramming then with slightly moistened metal grips for wall strapping If your house is in an area prone to to "float" during earthquakes, "like an up• earth, or dig a trench below frost level, fill it with well-consoli• flooding, the lower courses might require side down teacup." This would reduce the dated, washed gravel, then level the surface. Place recycled tires on stabilized earth in top stabilization with an additive such as ce• risk of breakage in the walls, as no rigid the gravel and ram them full of moistened earth. Concrete may be row of tires ment or lime. Better yet, design the house pressure points are exerted upward by the used to fill the voids between tires. Sometimes a concrete sill is to alleviate the problem of moisture alto• ground. poured into forms on top, with metal anchor bolts embedded for rammed earth in gether. For example, you can allow the The diagrams on pages 36-37 show sev• fastening down the base of the wall above. This method of attach• tires water simply to pass through the lower eral examples of foundation details. The ment is not considered adequate in earthquake regions. Tire foundation level. Remember that if the lower courses variations are innumerable, as the best so• with metal handles. are filled with coarse sand and/or gravel, lution will differ slightly for each type of Rubble or Mortared Stone which drains very readily, the house is not earth, climate, construction material, size This type of foundation can be made from large pieces of stone or likely to have its foundation washed out of structure, and budget. concrete rubble recycled from old pavement. A trench is dug, then from underneath (see sidebar on pages Earthbag or gravelbag foundations can large rubble pieces are carefully laid on undisturbed ground, with 36-37). Be aware that many "bag" materi• also be used for other natural wall systems, bent metal rods protruding to provide attachment points between als are subject to decay, and should not be including straw bales, rammed earth, cord- the wall and foundation. A rubble trench can provide good drain• relied upon to contain nonstabilized fill in wood masonry, and adobe. Especially in age if necessary. earthquake regions and when combining permanently or frequently wet conditions. Mortared stone/rubble To secure the lower course of earthbags earthbags with straw bale or cob construc• footing with metal from decay, you may fill the bags with soil tion, rebar or other pegs can be pounded grips for wall strapping, if required. 40 DESIGN, SITING, AND FOUNDATIONS 41

the mixture until it sets. No additional be rendered (plastered) or unrendered. Gabions compaction is needed. When used for wall construction, the A gabion is a latticework container woven out of willow or galva• Due to its low cost, high speed of con• pumice can be mixed with lime or clay in• nized steel and filled with loose stones, often used as a retaining struction, and insulative and thermal stead of cement, but this will require a wall. Like a rubble trench foundation, a gabion will drain away properties, creating very comfortable liv• separate foundation to raise the wall above moisture very effectively, so it can be used below ground as a foun• ing conditions, pumice-crete makes a ground level or a damp-proof membrane dation or partly above ground as a stem wall, isolating an earthbag good foundation, and some people are to prevent moisture wicking up into the wall from the moist ground. constructing entire buildings of this mate• permeable wall, which could be damaged rial. The walls of a pumice-crete house can by water dissolving the lime or clay. Dry-stone This type of foundation involves great artistry and requires a gen• erous supply of relatively flat stones. Many traditional buildings in stony locales have foundations of this type. Carefully selected stones are stacked on top of each other in overlapping courses, resting on undisturbed or well-tamped earth that is below the frost line or any ground movement.

Pumice-crete This building technique invented by Tom Watson has spread rap• idly in areas where pumice is a readily available resource. A very

Dry-stone wall. porous volcanic stone, pumice can be used as the aggregate with a mix of a little Portland cement and water to bind it together. A typical ratio is approximately 1 part cement to between 9 and 12 parts pumice, but test samples always need to be made. For greater strength, for example above doors and windows, use 1 part cement to 4 parts pumice. Pumice-crete actually uses very little cement compared with conventional concrete, as the more finely ground pumice combines easily with cement and adds to its binding strength. Pumice-crete can be mixed and poured into temporary or permanent forms. Due to its porosity, it acts as a good insulative material, needing no further insulation, and also provides thermal mass. Rigid temporary forms could be built in the same way as the formwork used for concrete and removed several days after pour• Pumice-crete stem wall. ing when the mixture has dried. Permanent forms could be galva• nized wire, or any type of bags, paper or plastic, that will contain 4

BUILDING WITH EARTHBAGS

he use of the soil-filled sacks called "earthbags" has in re• cent years been revived as a building technique, largely Tdue to the pioneering work of Nader Khalili at the Califor• nia Institute of Earth Art and Architecture (Cal-Earth). Its popu• larity is rising for several reasons. It is low cost in terms of tools and materials, utilizing available soil in almost any region, and requiring only a few skills that are easy to learn. The polypropylene or burlap (hessian) bags used to contain the soil can be obtained free or relatively cheaply. Earthbag walls go up faster than cob or adobe and are very flexible, unlike rammed earth, allowing the construction of any shape from very straight and square structures to free forms and domes. Earthbag structures can be adapted to any conditions, from regions that flood to the most desertlike lands. When constructed properly, they are strong and durable, expected to last for hundreds of years. And, because the bags are light and easily transported, they are extremely useful for emergency shelter, in areas that are prone to flooding, or in remote locations where little or no wood, stone, or A brick dry-stacked corbeled dome. clay is available. In chapter 2, we looked at the way that builders using masonry materials can build an arch by angling the bricks or blocks up at the outer edge, since they can be held in place by mortar, which dries solid. An earthbag dome cannot be constructed in the same way as a masonry dome. Due to the fluid properties of earth, each row of earthbags needs to be laid flat, then corbeled, or stepped Facing page: The art of earthbag engineering. Steve inward with each successive course, in the same way that a dry- Kemble in the Bahamas in 1998. block dome is corbeled. This corbeling makes an earthbag dome much steeper than a masonry dome. The corbeled earthen dome

43 BUILDING WITH EARTHBAGS 44 45

takes the form of a lancet arch, as described in chapter 2. If the rows The width of the earth-filled bag or tube complete within three months, all exposed of bags have been stepped in too fast, the dome will be shallower in after tamping will be approximately 13 per• polypropylene bags should be covered in its rise and there could be a danger of collapse. cent smaller than the width of an unfilled some type of finish to protect them from In this chapter, we will look carefully at the steps involved in bag or tube, and the depth when filled and ultraviolet rays. As a general rule, constructing an earthbag structure. Before describing techniques tamped will be about 30 percent of the In England, an 18-inch-wide tube of the lower the for filling and tamping the bags that serve as the "building blocks" original bag width. polypropylene costs anywhere from 17 to binding proper• in this construction system, I will enumerate the recommended Burlap is a natural woven fabric that is 40 pence per meter, plus delivery fee. In the ties of the fill, the materials and tools, then review key structural principles includ• biodegradable, and therefore more ap• United States, most manufacturers will stronger the bag pealing to those consciously trying to use ing the use of tension rings and compression rings, as well as the deliver a minimum of 1,000 yards at a cost materia! should

importance of corbeling in a domed structure and buttressing in a environmentally benign materials. How• of approximately 22 cents per yard, plus be. Corbeled earthbag dome buttressed by the ground. straight-walled structure. ever, you can only use burlap if the earth is delivery fee. See the resources list for infor• not pure sand (which will slip through the mation on ordering polypropylene tubes MATERIALS weave of the fabric) but contains com• on a roll. The materials needed for earthbag construction are relatively in• pressible particles of soil. Burlap bags are There are cheaper alternatives, if you expensive, very portable, and available nearly everywhere. If you heavier and bulkier than bags made of are prepared to be resourceful and persis• live in a place where these materials are difficult to find, see the plastic, and more expensive to ship. In En• tent in tracking down supplies. It is pos• resource list for suppliers who will allow you to order them for gland, an 18-inch-wide tube of hessian sible to use recycled bags, which might be shipment to your location or use the Yellow Pages to find local maybe purchased for anywhere from 30 to obtained from stores or factories that use suppliers. 50 pence per meter, plus the delivery fee. them for bagged produce. "Misprints" are The material is delivered in rolls of a few also available for a reduced price from Bags or tubes: The purpose of the bag is to retain the earth during hundred meters, and may be any desired some companies that manufacture the the construction process. It is a type of permanent form to allow width. In the United States, 18-inch burlap bags, as they sometimes make mistakes in costs approximately 50 to 80 cents per compass point the earth to be placed in a course and tamped solid. When the the printing process that render the bags building is subsequently plastered over these bags will no longer yard, plus the delivery charge. For an odor• unsuitable to their clients. Or you can How to construct an arch of an earthbag dome on be visible, and will be largely redundant in terms of their struc• less, nontoxic material, make sure that you make the bags yourself by obtaining inex• paper. tural function, since the plaster "skin" will contain the earthen get hydrocarbon-free burlap bags (Hunter pensive cloth or scraps, preferably mate• walls. Again, as a general rule, the weaker the mix, the stronger the & Kiffmeyer 2000). rial that does not tear too easily. Fold the Chemical composition bag should be. Polypropylene is made of woven threads cloth in half and sew along one side to of polypropylene. Bags can come ready-made or can be bought on a roll and cut of plastic (Richardson and Lokensgard form a bag or tube of the desired length. If to the desired length on-site (longer bags are called tubes). 1989). Polypropylene is a simple plastic the bags are filled with a material of high Two types of bags are available on the market: burlap (hessian) and is not as environmentally toxic as the binding property such as clay or stabilized and polypropylene, in a range of widths. Both types can be avail• infamous polyvinyl chloride (PVC). It is soil, the bags can be removed once set. able in tube form on a roll (usually 1,000 or 2,000 yards per roll), not biodegradable, although polypropy• or already cut up and sewn into bags. Presewn bags are generally lene bags deteriorate if exposed to ultra• Fill: The earth used to fill the bags can be violet rays, so care should be taken when more expensive, unless you can find a source for recycled grain, used as it comes directly from the site, al• Polypropylene tube on seed, or coffee bags or "seconds" with some kind of insignificant storing the material to protect it from di• though if it contains too much organic mat• a roll.

Sculpture made of burlap bags filled with sand. flaw that a manufacturer may be willing to sell cheap. rect sunlight. If a building project is not ter or too many large stones that prevent 6 BUILDING WITH EARTHBAGS 4 47

good compaction, these need to be sifted Stabilizers: These are additives mixed with Tamper: This essential tool is used to tamp can also be used to flatten the sides of an out. The soils can range from high clay the soil for increased strength, or to fortify or ram the bags flat once they have been earthen wall or to beat the bags into any content to very sandy consistency and may a finish coating. Typical stabilizers are lime laid in place. Garden supply stores and shape desired. include other materials, such as gravel or or cement. If constructed properly, an building centers sell manufactured tam• pumice. With clay-rich soils, you could earthbag structure should require no sta• pers. You can make a metal tamper out of a A stand: A fold-out stand will aid in the consider building instead with adobe or bilization. Cement can be used for bond- piece of 1-3/16-inch (30 millimeter) diam• filling of small bags. (To ease the filling of cob techniques. (See chapter 7 for more beams and compression rings, for ex• eter metal pipe about 40 inches (1.5 longer bags or tubes, prop a cut-off piece about clay-based building methods.) If tremely strong structures that must carry meters) long welded to a 6-by-6-inch (150- of pipe in the opening.) you're determined to use earthbags, mix great loads, or for structures that are under by-150-millimeter) square of metal plate more sand and gravel into the mix to break water. Be especially careful when using ce• about ¼ inch (6 millimeters) thick. To Water source, or buckets for hauling wa• up the clay, or tamp it well and ensure a ment, which while ubiquitous in our soci• make an even lower-cost tamper, take a ter: If the soil is too dry, water may be high stem wall to minimize its ability to ety, is associated with negative environ• plastic yogurt cup, fill it with concrete mix, needed to help make an earthen mixture absorb moisture. mental impacts. Cement-based finishes and place a stick studded with nails in the more compactable. One of the reasons should be avoided with an earthen build• center of the wet concrete, possibly with that earthbag construction is very well- Water: This is added to the earth to facili• ing, because cement makes the walls more rolled-up wire mesh for reinforcement. suited to dry locales is that you can also fill tate the tamping, in order to achieve better impermeable, and earthen walls must Let the concrete cure for at least two weeks bags with dry sand, gravel, or sifted soil. compaction. The moisture content of the breathe over time. (The only exception is before use. earth should be such that when a handful on domed structures in very wet climates.) A heavy block or chunky piece of wood Water level: for leveling the ground. is picked up and squeezed it holds its Instead, the finishes can be earthen plas• Making a tamper. shape, but you do not see or feel any liquid. ters with a lime sealant or render. Other

To prevent an excess of moisture, the earth options for finishes on earthbags are dis• Left: The tools for mixture can be soaked overnight. cussed in chapter 6.

Barbed wire: This is used between courses TOOLS instead of mortar to grip the bags. Four- The tools you will need to build with point wire provides a good grip; as a natu• earthbags are simple and easy to find or ral alternative, you can use branches of a make yourself.

Four-point barbed wire thorny plant or jagged rocks or stakes on a roll. pounded into the bags. Barbed wire can be Coffee can or shovel: Either may be used obtained on a coil or salvaged from an old for filling the bags or tubes. Cans are easy fence. If the bags you are using are 12 to toss to people who are higher up on the inches (300 millimeters) wide, only one wall, but each person will find his or her row of wire is needed. If the bags are 16 own favorite tool and technique. inches (400 millimeters) or wider, two rows may be required. Shovel for digging: A shovel with a cutting edge will make it easier to excavate soil from the site, to trench, or to collect fill. BUILDING WITH EARTHBAGS

wheel has been removed. The caster will really necessary. However, bags are faster Plumb line: A plumb bob and line allows allow for rotation as well as up and down to construct than cob. you to check a straight wall for vertical lev- movement. The caster should be affixed to If pure sand is used, you must take sev• elness. a 4 x 4 (100 x 100 millimeter) post planted eral precautions. The sand must be made upright in the ground at the center of the slightly damp to facilitate the compaction. Wheelbarrow: This is used for transport• dome. At the upper end of the pipe, use The bags need to be wider to allow for ing material, for mixing cement or lime pipe clamps to attach a guide made of an more stability, more buttressing needs to into the earth to stabilize it, or for mixing L-shaped piece of metal. be provided, and if domes are being con• adobe or cob plaster. structed using the corbeling method, care PREPARING THE FILL needs to be taken that each row does not Hoe: This may be more practical than a As I have explained, the bags are used as a step in too fast. This type of dome can ac• shovel for mixing ingredients. temporary formwork for the tamped or tually be much taller than masonry domes, rammed earth during construction of a with steeper sides and larger buttresses, Section of earthbag dome showing the compass in use. Blade or scissors: For cutting the bags or building and before the plaster is applied. such as on Shirley Tassencourt's dome (see tubes. The plaster finish can be seen as a long- diagram, page 124). For increased stability, term sheathing, which if maintained at• it is also possible to tie down one course of Wire cutters, level, ladder, tape measure, tentively can be considered "permanent." bags to the two below, creating a net with gloves, and trowel: All of these will prove The material that goes into the bags can wire mesh or strapping, or to construct the useful on any building project. therefore be of any consistency ranging dome over a permanent form such as from very loose—for example gravel, demonstrated in the Malawi project (see Compass: Required only as a placement pumice, or sand—to a more compactable page 142). guide for the bags in the building of sym• soil that contains varying amounts of clay. Whenever earthbags are used, but espe• metrical domes, a compass can be as simple The best fill for an earthbag wall is one cially in flood areas, care needs to be taken as a chain or a string, or more complex. with the same consistency as the tradi• that the lower courses of the wall do not When the courses of the dome reach the tional mix for rammed earth: approxi• contain clay, and are properly detailed to stage at which they must start to curve in• mately 25 percent clay to 75 percent sand, shed water (see drawings on page 35). If A construction compass, made with wards (the spring line) the compass needs which will dry into a cementlike hard bags containing clay are exposed to water, telescoping pole and caster. to be extended after each row. This can be block. However, earth seems to be suffi• the clay can either expand and break apart worked out by making a drawing of the ciently compactable with as little as 5 per• the wall or dissolve and seep out, leaving dome, as in the drawing at left and page 44. cent clay. cavities that create instability. The higher An extendable compass may be made With soil that has a high proportion of courses need to be tamped or rammed well with a length of hollow pipe (electrical clay, it is probably better to consider an al• to reduce the ability of any clay in the bags conduit will work, or one of those tele• ternative type of construction, such as cob, to absorb moisture. scoping poles used for cleaning swimming adobe or one that makes use of other fiber/ Generally, the earth excavated on site pools) attached at one end to a caster (such clay composites; because the clay has bind• can be used for fill. Be sure to remove top- as those on a grocery cart) from which the ing properties, a bag to contain it is not soil and set it aside for a future garden, in- BUILDING WITH EARTHBAGS 51 50

the person doing the work can lift. It is later fold over the surplus fabric to close stead using the subsoil for construction. only attending to these very general guide• never necessary to lift the bag itself: the bag the bag. Remove all large stones and organic mat• lines: not too much clay, not too many stays in place and earth is brought up to its A mechanical pump used for pumping ter from the earth mix, as these materials large or sharp rocks, not too dry or too wet. opening. Bags higher on the wall can be concrete can also be used to speed up the too could create cavities later on. If a large For information about doing soil tests filled in place. Cans of soil can be thrown process of filling the bags. For landscaping number of stones are found in the soil, when building structures that require up to the person doing the actual filling or large industrial projects, where time sift them out using appropriately sized more refined sensitivity to soil contents, (see photo on page 53). Bags filled by dif• and labor are costly, professional builders screens, and use them as gravel in the see chapter 7. For information about stabi- ferent people will vary in thickness, due to might use a continuous berm machine, lower courses of bags or for foundations, lization, see chapter 6. differences in strength and technique. It is which extrudes a fabric-encapsulated con• as this nonabsorbent material will drain therefore important that one person or tinuous berm of sand, rock, or native soil well and prevent capillary rise of mois• FILLING BAGS OR TUBES team builds a whole row to minimize the at a rate of 10 to 50 feet per minute. ture. If crushed pumice or scoria (a po• Before beginning to fill the bags, make sure changes in thickness during one course. Filling the bag from rous volcanic stone) is used for earthbag the earth is moist enough to allow com• both ends. The rows may vary from each other, but as Filling a Bag with More than Three People walls, it will serve as both thermal mass paction. Bags may be filled in several ways: long as each row is of a consistent thick• Two teams can fill a long bag or tube from and insulation (as in the Hart's house, with a shovel, tin can, bucket, or whatever ness, this is not a problem. Once a row is profiled in chapter 8), but smaller-sized the two ends using the following procedure: complete, tamp it well, then place two particles can wick moisture, so care strands of four-point barbed wire on top should be taken not to use too much fine 1. Cut the tube to length (up to 30 as keying for the next row. As you stack pumice or scoria in the lower courses, feet). bags in successive courses, remember to which are prone to being damp unless a 2. Fold the edges of each opening back always stagger the joints, just as in ma• damp-proof membrane is used, or unless as far as possible toward the middle, sonry construction. the pumice is mixed with cement. (For as shown to the right. discussion of pumice-crete, see chapter 3.) Each tube or bag can be cut to the de• 3. When the folding reaches the mid• sired length. How long do bags need to be? point, start filling the tube from each If the earth used for filling is totally dry If you are building a dome, it is good to open end. As one person shovels in when dug out, it needs to be sprayed with have one continuous length all the way the earth, the other can hold the end water to ease compaction in the tamping around, unless this would mean a length of of the tube open and unfold the ends process. More compacted fill is ultimately more than 30 feet, because beyond that, as it is being filled. more stable. Remember, the soil should be the tube becomes difficult to fill. moist enough that when a handful is picked up and squeezed it holds its shape, For the foundation and the first few The speed of this method of filling bags but you do not see or feel any liquid, and rows of wall, it is good to use bags or tubes on the project in Mexico (see chapter 8) when a lump of the soil is dropped it falls that are as long as possible to minimize averaged out to be 25 feet per hour, per apart. The soil can also be soaked over• breaks, for structural stability, but even team. small bags that are well tamped can be Two strands of barbed night. used for the foundations. When measur• wire placed between The appeal of the earthbag method is bags during construc• ing the required length, add an extra foot that builders can use such a wide variety of Filling the long bag tion act as a mortar. of fabric at each end of the bag. You will soil and other types of fill for construction, from one end. A team of three filling a long tube in Mexico. 52 BUILDING WITH EARTHBAGS 53

barbed wire when working on top of a Filling Bags or Tubes with Only One course that has been keyed with wire. to Three People Far left, top: Using the metal Using Small Bags When working with fewer people, the bag tray to position the first bag or tube should be filled from only one If small bags are used, the wall will tend to correctly. open end. Once the desired length of bag is have a great many bag corners sticking out, Far left, bottom: Filling the cut, shovel or scoop as much material as which makes plastering difficult, as much long tube using a plastic you can lift into the bag, then shake it more plaster is needed to cover these. To pipe as the chute. down to the opposite end. While one per• prevent this, tuck in the bottom corners as son shakes the earth toward the end, a sec• the bags are being filled. Utah earthbag Left: Filling a bag using a ond person can step on that end to prevent builders Kaki Hunter and Doni Kiffmeyer stand. the material from flying out. named this process "diddling." When filled, Or, when working with smaller, more the open end of the bags can then be gently Below: Steve Kemble portable bags with one end sealed, you can lowered into place and those corners tamping an earthbag wall with a concrete tamper in shake the material down into the open diddled as well, tacked under the weighted the Bahamas. end, and lift the whole bag into position. end of the full bag. Once the bag is in place, fold under the One person can fill small bags by using Inset: Untamped and tamped sides of a wall. open end of the bag to close it. When a row a stand to keep the end open. Remember, is complete, this bag should be tamped the small bags must be laid in a running solid and flat before the next course is bond, with all joints staggered. The time "Diddling." placed on top and is ready for barbed wire. required to fill small bags for the Honey Another way to fill bags with a smaller House project (see chapter 8) averaged crew is to slide a cut piece of wide pipe in• four bags (approximately 6½ feet or 2 to the open end of a bag, like an ankle in a meters) per hour, per person. sock. The pipe forms a chute for the earth to go through. Each time a manageable TAMPING amount is shoveled in, take out the pipe As noted above, to minimize unevenness, and shake down the bag. Be sure to avoid each bag in a row should be filled to its letting the bag bunch up while it is being maximum capacity by the same team. To filled; each load of earth must go all the create as level a wall as possible, do not way to the end, with no gaps. A brick can tamp until the whole row is filled. Once the be placed under the bag to prevent creases whole row is laid, it can be tamped until no in the bag, or one of the crew can use a foot movement of the earth is felt. The sound of to support the lower side of the bag as it is the tamping, changes as the earth in the bag filled. Use a piece of sheet metal or a board is compacted, becoming less of a "thump" to protect feet and clothing from the and more of a solid "smack." BUILDING WITH EARTHBAGS 54 55

Tamping soils with high clay content lessens the earth mixture's tendency to draw in moisture, but does not eliminate this ten• dency entirely. Be sure to avoid having too high a proportion of clay in the earthbags, especially in the foundation or lower courses, Points to Remember for which are more likely to be exposed to water. Earthbag Construction You may also wish to tamp the sides of the wall, checking the vertical straightness with a spirit level or plumb line. An advantage • Dampen the earth prior to filling the Reinforced tension ring. Bench acting as a buttress. Ground acting as a buttress. bags to improve compaction of tamping the sides is that then the wall surface will require less

• In successive courses, stagger all joints plaster. The disadvantage of a very level or even wall surface is that dome, which absorbs the downward hori• between bags, for stability the plaster has less surface area to key into. stabilized rammed earth, metal, or some

• Have the same person or crew fill the zontal forces that otherwise would cause other resilient material. Since this rein•

bags for a complete row or course, for KEYING the base of the dome walls to splay out and forced ring may be the most expensive el• consistency After tamping, each course needs to be keyed with four-point collapse. This ring has the same function ement in an earthbag dome, it may be ad• • To minimize unevenness, do not tamp barbed wire or branches of a thorny plant, which will provide fric• as buttressing and is needed in all struc• vantageous to consider buttressing the until a whole row is complete tion to prevent any shifting of the bags over time. If no barbed wire tures in seismic zones and in domes that structure in areas that do not have seismic • In dome construction, tamp each row is available, the bags can either be well buttressed, tied to the bags do not have some form of buttressing activity (see the diagram series above). flat, for stability below (see Kelly Hart's project in chapter 8), sandwiched between around the base. In most domes, unsta- A compression ring is the tension ring's • Place barbed wire or other key in wooden poles, or pinned with reinforcement rods. For very wide bilized material may be used in the bags counterpart at the top of the dome, neces• material between courses and short stem walls or landscaping walls, barbed-wire keying is with which the walls are constructed, but sary if there is an opening there. It pre• • Buttress all domes and straight walls not necessary. Also, on smaller structures, using rough rocks or in seismic regions the ring around the base vents the dome from caving in because of chunks of gravel between courses will provide adequate keying. must be stabilized with continous reinforce• If the bags used are wider than 14 inches (350 millimeters), or a ment surrounded by concrete or cement- dome is being constructed, two rows of keying maybe necessary. This keying is especially important in corbeled domed structures, providing tensile strength while enabling each row to step in slightly.

skylight STRUCTURAL REINFORCEMENT AND BUTTRESSING In domes, there are two areas of maximum pressure that require concrete bond beam with careful attention, especially in areas of high winds or seismic activ• continuous reinforcement Buttressing wire. Each row of bags is tied to the ity. The base of a dome can be buttressed on the outside with the Earthbag dome with a compression ring and skylight. two rows below. ground, with constructed benches, or reinforced with a "tension ties on to 3 or ring." The other point of pressure is the top of the dome. If there is 4 rows below bags filled any opening at the top, it must be reinforced with a "compression with earth ring." A tension ring is a continuous and rigid ring at the base of the BUILDING WITH EARTHBAGS 56

the upward, inward pressure of that open•

Buttressing during ing. Like a tension ring, a compression construction at ring needs to be continuous, made of con• Allegra's house, crete, metal, wood, or other material con• Arizona. taining sufficiently sized continuous rein• Corner of a buttressed house. forcement. For more complex structures, consult an engineer. While curved walls are structurally self- supporting, straight walls need additional support. The diagrams on this page show

ways of reinforcing a straight wall with a corner or with connected buttresses. Re• member, for stability when constructing intersecting walls and buttresses, always If a wall is straight, buttressing needs to stagger all joints. Staggered joints

at the corner of OPENINGS the Three-Vault House, Mexico. In an earthbag dome, the number of open• ings cannot be too many or else the struc• tural stability of the dome will be compro• mised. The distance between openings should be large enough to properly but•

Long bags"woven" If the wall is curved it does tress the arch that forms each opening. In into place during not need buttressing. general, openings that are square are best construction of the author's retreat. suited for square houses; it is possible to create small square openings in domes if there is a lintel, but structurally this is not a good idea. During wall construction, where there will be openings, leave loops of wire ex•

A buttressed wall. tending out from the strands of barbed wire laid between the bags, which will BUILDING WITH EARTHBAGS 59 58

allow you to tie off these wires up and down around the opening

for added strength. Some builders reinforce their openings with Size and position of the form wire mesh, which can also be attached using these wire ends. used to make an arched There are two categories of openings: arched, which do not need opening in a corbeled dome. line of wood, metal, or concrete as a lintel above, or square, which need curvature lintels, or which utilize a bond beam at the top of the wall as the

lintel. wedge

Arched Openings If the opening is in the shape of an arch, no lintel is necessary. One

way of leaving an opening in the earthbag wall is to use a form. A wedge form can be a circular object such as a wheel, a bucket, or a barrel, or can be specially constructed out of timber in the exact space desired. The opening can also be filled with earthbags that are sub• sequently removed. Several types of arches can be created, some of which are shown in the drawings and photos. To make the "curved bag" window Stitching keystone shown above, stabilized earth must be used. stabilized bags after filling in Construction of a form to create an arched window bags To make a form, cut an arch in the required shape out of ply• opening. place. wood or other flat material and duplicate it, then attach these flat arches to each other with pieces of timber so that the ends are parallel. Next, cover the whole arch with plywood or other flexible, but this can be expensive because of the As you stack the first three rows of bags Several demonstrations of creating an opening quantities of materials required. It is less without the use of a wooden lintel. sheetlike material. around the form, add additional perma• expensive to make a permanent vault out Make the form at least 2 inches (50 millimeters) wider on each nent buttressing on either side of the pri• of bamboo or other bendable material, side than the intended size of the finished opening, to allow for the mary bags to contain the horizontal forces which the earthbags can be layered thickness of the plaster. that will act upon the finished arch. around, or a Nubian vault out of adobe When placing the form, make sure to position it on top of The arch's "keystone" will consist of the (see page 25-26). If you do decide that a wedges, as this will ease the removal of the form after the arch is last three bags laid in position. These are temporary vault form is necessary, it is complete. These wedges could be chunks of timber or tapered log placed with their tops still open, then filled most economical to make one that can be ends. up with additional earth from above, as reused rather than demolished. Place a minimum of three well-tamped courses of bags above shown above right. The earth must be the opening before removing the form. When the earthbag wall reaches the shoveled into the last three bags simulta• height of the opening's bottom sill, place a When building a vault that connects to a structure through an neously, to create the keystone effect. To form where the opening will be, posi• arched opening, the main opening should be located at the end close these bags, either use nails (stuck like tioned on top of wedges to ease its removal Shirley's dome, showing different formwork on top where the arched opening in the wall has no load-bearing function tailor pins through the fabric of the bags), of the wall. after completion of the arch. (see page 26). Some builders have constructed reforms for vaults, or stitch them closed with a piece of wire. 6o BUILDING WITH EARTHBAGS 61

As emphasized above, before removing the form, you must complete the rest of the wall with at least three tamped rows laid on top of the arch. metal tray

lintel is pinned to Square Openings earthbags Although square openings for windows and doors are not struc• turally sound in dome construction, you can incorporate square openings in a straight-walled earthbag building by providing rough framing ahead of time or by cutting them out from the fin• ished wall, provided the necessary buttressing is in place prior to this excavating. As shown on page 61, it is important to add sturdy diagonal Door frame securely fixed to stern wall bracing to all window and door frames to keep them square during with diagonal bracing.

construction. This bracing can be removed once the walls reach Elevation of doorway. Section through doorway. full height. Door frames also need to be securely attached to the foundation for stability.

The detailing around window and door openings—for in• Below and bottom right: Window details. Always slope the external window stance, the seal between a windowsill and the earthbag wall be• sill away from the building with an overhang of at least 2 inches (50 mm) and a drip edge. low—is extremely important in order to prevent penetration of moisture. Also note that if a timber frame is used to provide the structure for a building where earthbags serve as infill, it is impor• window tant to separate wooden members from the earthwall with a care• timber windowsill with a drip edge fully attached waterproofing membrane to prevent moisture pen• damp-proof course etrating through at seams between the earthbags and wooden timber sill plate internal plaster Window frame. posts and beams or framed openings. (See chapter 6 for more in• metal lath _anchor bolt to fix sill plate to cement-stabilized formation on waterproofing.) cement-stabilized earthbag earthbag

BOND BEAMS Known in conventional construction as a "plate," a bond beam is a rigid structural unit, usually made of wood, metal, or concrete, that sits on top of a wall and evenly distributes the weight of a subsequent floor or the roof. While not relevant to dome construc• tion, bond beams are important in straight-walled construction to tie together and stabilize the earthen structure at its point of great•

Top: Window in the end of a vault, Mexico. est outward pressure, especially in areas of high winds or earth• Middle: Stabilized arch, California. quakes. In addition to serving as a level platform for a roof, a bond Bottom: Arched forms. 62 BUILDING WITH EARTHBAGS 63

beam can also serve the function of a lintel, its function, the bond beam can be made spanning the unsupported gap in a wall of timber, steel-reinforced concrete, or created by a window or door. even cement-stabilized earth, well tamped In an earthbag building, depending on in the bags.

Far left: A bond beam in the Bahamas.

Left: A formwork for the bond beam, which will be used as a base for the timber wall plate of the next level.

Below: A conven• tional greenhouse in Colorado constructed over a pumice-filled bag stem wall. Inset: Section through the stem wall of the greenhouse showing the wall plate detail.

damp-proof course row of well-tamped cement- stabilized soil

papercrete (fibrous cement) internal and external plaster well-tamped gravel bags 5

ROOFS

he roof is one of the most impor• ture, making a house stand out, or can help tant factors keeping a building dry a house disappear gracefully into the land• Tand warm. A good roof protects scape. the inhabitants from rain, snow, wind, the The ideal roof for earthbag walls is one Facing page: Cooling cold, and the heat. It will shed water away constructed using the same materials as tower of the three- vault house at Cal- from the house, directing it at the garden, the walls. The main attraction to most Earth. or will catch the rainfall to be stored for people who discover this building tech• later use. The roof can be a dominant fea• nique is the possibility of using no wood,

adobe plaster with shallow-root plants and grass planted to prevent it from being worn away by rain stabilized adobe (only recommended in rainy areas; otherwise the waterproof layer grass will dry out) two rows of stabilized patties

A grass covering. In rainy climates a waterproof Covering for damp climates (see page 98). The outer Natural roofing membrane is necessary. stabilized layer could also be made of papercrete. materials for earthbag domes.

bamboo or willow wrapped around shingles of grass, overlapping like tiles

65 66 ROOFS 67

metal, or concrete, as well as the aesthetic value of an earthbag

structure. A dome, for instance, is quite an amazing space to be in VAULTED ROOFS (some would say "nourishing for the soul") with an option of add• Ratio of Vault Width to Length To my knowledge, a vault wider than 5 feet (1.5 meters) has not yet ing at least one other floor while retaining its height and beauty. In vaults constructed out of earth (for been successfully constructed using earthbags. Most vaulted roofs Using a dome or vault is a roof-building technique that is finan• example, adobe), a safe ratio of width to are constructed from other materials and joined to the earthbag cially and ecologically economical if no plentiful, renewable length should be equal to no more than: walls using a bond beam. source of wood is available. Concrete and steel contain high em• If the soil contains some clay, one way of constructing a small length = 1.5 meters x width bodied energy, as well as being expensive, and earth is a far vault out of earthbags (approximately 3 feet [1 meter] in width, with the width not exceeding 12 feet (4 healthier option. which can serve as a connecting space between domes) is by stand• meters) overall. Yet, creating an earthbag dome might not be a solution to house ing the bags up and placing them in a leaning arch, as shown in the design in all climates, nor for every type of budget, culture, or in• For lancet vaults, the following ratio applies: top diagram. dividual. The amazing aspect of the earthbag technology is that it Another better way of constructing narrow vaults is to create a rise of vault = width/2 + 19.5 inches (50 is genuinely adaptable, allowing each individual to create a house series of sturdy, self-supporting arches that, when joined together centimeters) tailored to his or her needs. In many cases it is beneficial to com• and finished with plaster, create a continuous vault. Detail of a brick dome showing the bond beam. bine the earthbag wall system with a flat, pitched, vaulted, or other roof system, depending on the requirements. For example, in areas prone to high levels of rainfall throughout the year, it is a good idea to combine the earthbag wall system with a more conventional roof type that provides an overhang to protect the walls from the constant rain. Surface Finishes BRICK OR ADOBE ROOFS Surface finishes for domed earthbag roofs,

to make them water-resistant though not An earthbag building can be covered with a shallow dome con• A series of arches necessarily waterproof: structed out of masonry brick or adobe in areas where the climate A narrow vertical leaning vault, as constructed for a passageway in the retreat. creates a narrow vault. is relatively dry. • lime render or whitewash According to an old recipe I found on the straw bale listserve carrizo, bamboo, straw-clay mix for insulation • cement-stabiiized soil or hazel, or any (http://solstice.crest.org/efficiency/strawbale-list-archive/ bundled reeds water-resistant layer • papercrete that can be bent index.html), a cheaper and more beautiful way of waterproofing earthbags • earthen plaster with lime render and into an arch

whitewash exposed bricks than covering them with cement or boards is to: concrete bond beam

damp-proof In wet climates a waterproof layer is straps Stir 1 pound of finely powdered flowers of sulfur into 8 course necessary underneath the plaster or pounds of linseed oil. Bring the mixture to a heat of 278 Carrizo and earthen vault. painted on top. degrees Fahrenheit, and then allow it to cool. Add some drying oil and paint the bricks with the compound. timber bond beam anchor damp-proof course bolted to cement- stabilized For more on waterproofing, see the discussion of finishes in chap• Detail of vault constructed in earthbag ter 6. Mexico out of carrizo. below ROOFS 68 69

CONVENTIONAL ROOFS WATER-CATCHMENT ROOFS More conventional roof systems can also Another supplementary purpose of a roof be constructed on top of the earthbag can be to catch rainwater to be used for walls. The roofs are for areas with high washing, flushing toilets, watering the gar• rainfall. It is always important for the roof den, and even drinking after filtration. For to have large overhangs (at least 18 inches directing run-off to a water-storage reser• [45 centimeters]) on the sides, even the less voir, a good roof material is zinc-coated exposed ones. From the standpoint of en• metal, because ethylene propylene diene vironmental impact, it is better to create monomer (EPDM)—the synthetic rubber roofs out of small sections of wood, if commonly used for roofs, pond liners, and wood is necessary at all, instead of timbers water tanks—is apparently slightly toxic. from old-growth or slow-growing trees. The water can be collected into a cistern Wood can be obtained from fast-growing located either inside the house or out in the trees in carefully managed forest planta• garden. If it is placed inside the house, care tions, or builders can use wood-efficient needs to be taken of its location to avoid its trusses, laminated timbers, or other engi• functioning inadvertently as a very large neered wood-fiber products. Trusses can heat sink, constantly drawing heat from be purchased prefabricated or can be built the house's living space. In a passive solar on-site with local materials. A typical 2 x 4 building, the additional thermal mass of truss provides a great deal of space for in• the water in the tank can help store solar Types of trusses. sulation but does not provide extra living gain. The water tank should be insulated, space, unless the scissor truss is used (see which can be done with straw bales. top diagram).

THATCHED ROOFS A long tradition in England, Ireland, and Wales, thatched roofs are still in use today on most cob buildings. Throughout northern Europe, thatch was made of a common reed grass (Phragmites) or tight bundles of straw, usually wheat or rye. Thatch conforms nicely to curved and ir• regular roof shapes. The biggest advantage of thatch, in addition to its aesthetic value, is that the thatch itself is the waterproofing layer and therefore does not require the 70 ROOFS 71

addition of any artificial waterproofing This type of roof needs enough rainfall to ensure the watering materials; moreover, thatch provides suffi• LIVING ROOFS of the vegetation, or the roof can be planted with local plants that cient insulation. A well-made thatch roof A "living" roof is one that supports an do not require watering. Ideally, the roof's pitch should not exceed can last a long time: straw thatch up to earthen mulch and plantings of grass, 35 degrees, or the mulch and plants may slide off, especially when forty years, and reed up to sixty. The main mosses, or even a berry patch. This kind of wet or weighed down with snow (it is possible to construct a sys• disadvantage of thatch is that it is combus• roof can be aesthetically pleasing, and can tem of shelves and netting to prevent soil slippage). tible, but the fire danger can be substan• make a house blend in to its surroundings. The layers of a typical living roof are as follows, starting from tially reduced by incorporating measures The earth on the roof serves as extra pro• the lowest layer which sits on the roof rafters: such as ceilings that reduce airflow to the tection for a waterproof membrane be• roof, a sprinkler system, or treatment of neath, and in addition to helping the house 1. A layer that creates a smooth surface. This can be anything Roof trusses coming together in a vortex. retain its coolness in the heat of the sum• Straw-clay rolled onto the roof with flame retardant, as discussed from plywood sheathing or boards to a smooth insulative long straw, reed, or jute in Michael G. Smith's book The Cobber's mer, the thickness of the roof covering is a straw-clay finish on top of rough surface decking such as spanning between Companion or Michel Bergeron and Paul sound insulator. Such roofs have also been carrizo (see figure c left) or previous straw-clay layers rafters. When straw- known to protect houses from external clay rolls are used, no Lacinski's book Serious Straw Bale (see the (figure a). If plywood or boards are used, and the roof has a board or mat is bibliography). fires. steeper pitch, it is advisable to create a textured surface to required to support the prevent subsequent layers from sliding off (figure b). straw-clay mix. Nailing on some 2 x 4 boards, or shaping the straw-clay to create horizontal undulations, will help (figures b and c). 2. A waterproof membrane such as bentonite clay with a layer of geotextile membrane to prevent root penetration, or polymer-based modified bitumen, or some other kind of

durable, reinforced, and impermeable sheeting. Roof construction consisting of carrizo decking with 3. A cushioning layer of corrugated cardboard or carpet scraps straw-clay for insulation used on houses in Xochitl, Sonora, Mexico. placed on top of the waterproof membrane to prevent it A. Detail of living roof B. Detail showing the layers C. Detail showing from being punctured and to give the vegetation something layers of a living roof showing straw-clay"rolls" of a living roof with plywood to take root in. for insulation. with straw-clay option 4. A layer of soil or other organic matter 2 to 8 inches (50 to 1. Insulation between rafters covered with a 1. Rafter. 1. Rafter 200 millimeters) deep, seeded with plants. Rock gardens are 2. Carrizo decking. 2. Plaster finish. ceiling finish. 2. Plywood or other rigid board. 3. Straw-clay for insulation. of course more appropriate in drier climates. 3. Straw-clay. 3. Timber batten (50 x 100 mm) to stop the soil 4. Two layers of waterproof membrane. 4. Long grasses or reeds covered with straw- from sliding off an angled roof. clay and rolled up to create an insulating 5. Corrugated cardboard or carpet scraps. LOW-COST FLAT ROOFS 4. Corrugated cardboard or carpet scraps. layer. 6. Soil. 5. Two layers of waterproof membrane. Roofing is one of the biggest challenges in low-cost construction, 5. Two layers of waterproof membrane. 7. Plants. 6. Corrugated cardboard or carpet scraps for 6. Corrugated cardboard or carpet scraps for cush• since it is usually the most expensive part of the structure. When I cushioning to prevent puncture of the ioning to prevent puncture of the waterproof worked in Mexico on a housing project organized by the Canelo waterproof membrane and to give the membrane and to give the roots a base to wrap Project, the roof systems developed were for straw bale houses roots a base to wrap around. around. Cardboard box roof construction used on the houses 7. Soil. 7. Soil. that cost between 350 and 500 U.S. dollars. The roof types we used in Aves del Castillo, Sonora, Mexico. 8. Plants. 8. Plants. ROOFS 72 73

there are also well suited for low-cost insulation blown in between rafters, which proof membrane is placed between the powdered marble, white cement and acrylic waterproofing as the earthbag construction. could be recycled cellulose, hemp, wool, or decking and the straw. Then straw bales roof finish For the rafters we used 3- to 4-inch- (75 coconut fiber. As for insulating a flat roof, are laid flat, leaving a gap of 3 to 4 feet (1 if pumice is locally available it can be used straw-clay to 100-millimeter) diameter poles, dis• meter) at the edges where flakes of straw by placing 8 to 12 inches (200 to 300 milli• can be used to taper the roof to the height layers of carrizo forming carded from timber cutting operations the roof decking because they were too small for convenient meters) or more of small pumice (only of its frame. When the bales have been laid, 75-100 mm (3'-4') Ø vegas milling. The roof surface or decking was small particles of pumice wick moisture) cut all the strings to loosen the straw. For earthbag wall constructed of carrizo and covered with with 6 inches of earth on top to allow for the first winter and spring, leave this ex• two layers of straw-clay mix. The first layer planting. An insulated roof has to be posed to allow the straw to soak up the framed in at the edges like a box to contain moisture, then cover it with a very thin Roof construction using cardboard boxes filled with straw on a concrete- of the mix contained uncut straw to sculpt the large volume of materials. reinforced grid supported by chicken wire. the parapets and build necessary thickness layer of aged compost and sow flower (6 to 7 inches) to provide reasonable insu• Another type of insulated living flat seeds. The best plants for such roofs have a lation value. The second layer contained roof uses straw bales as insulation. The shallow root network and retain moisture

powdered finely chopped straw and clay to even out slope should not exceed 30 degrees. As in well, for instance strawberries. Imagine marble, white the other living roofs discussed, a water- having a roof full of strawberries! reinforced concrete beams cement and the surface and prevent puddles. The roof forming a lattice around the acrylic boxes waterproofing as finish was a mix of powdered marble, the roof finish white cement, and an acrylic waterproof• ing compound as a final coating (see the cardboard box filled discussion of waterproof finishes in chap• with straw Natural Finish for Flat Roofs ter 6). A durable finish for flat straw-clay roof surfaces can be made with a capping of two coats of

chicken wire Another low-cost alternative option for ½-inch (12 millimeter) lime render (1 part lime to 3 parts sand). a dry climate (used by the Canelo Project in Mexico) is a roof made out of cardboard Here are two recipes for waterproof finishes to be painted on the surface: Roof construction consisting of carrizo decking with straw-clay for insulation and sculpted parapets. boxes filled with straw or other insulating 1. Dissolve 2½ ounces (70 grams) of alum (aluminum potassium sulphate) and 2½ ounces (70 material, which are laid flat on some form grams) of salt in 2 cups (Viz liter) of water. Add this mixture to 5-1/3 quarts (5 liters) of water and of inexpensive joist or rafter arrangement, mix in 1/16 sack of lime. Use this to paint over the finished lime-plastered roof surface. powdered marble, white cement or chickenwire for support, as shown at and acrylic waterproofing as the 2. Apply five coats of dissolved alum and soap, alternating these in the following way: roof finish left. Day 1: Dissolve 14 ounces (400 grams) of soap in 4 cups (1 liter) of hot water and brush on roof surface. straw-clay ROOF INSULATION Day 2: Dissolve 14 ounces (400 grams) of alum in 4 cups (1 liter) of hot water and brush on carrizo Many materials can be used to insulate a roof surface. precast concrete roof, the lower-cost options being straw- "vigueta" clay (a thick clay slurry mixed with a lot of Alternate these for five days, and reapply every year or two. straw, as shown in figures a and c on page Recipes make enough finish for approximately 30 square meters. Precast concrete vigueta roof system with carrizo and straw-clay insulation. 70) or straw bales, as described below. A Viguetas are short structural supports that span between main beams. Instead of slightly more expensive option would be concrete viguetas, short timber poles could be used. 6

WEATHERPROOFING AND FINISHES

s with any building, keeping the within the first two months of exposure to water out of an earthen house is ultraviolet light (direct sunlight), as UV Aone of the greatest concerns of light makes the bags deteriorate, exposing builders. As the cob builder's proverb of the material inside the bag. If the material Devon, England, says: "Good shoes, good inside the bag has 10 percent or higher clay hat, and a coat that breathes." This is what content and the structure was properly an earthen house needs to survive for tamped or rammed throughout the con• many decades. struction process, the walls should remain Good shoes, to raise the building suffi• solid and stable even when the bags have ciently off the ground—a sturdy, well- deteriorated. However, if the fill is of a drained foundation. loose composition, such as silt, sand, grav• Good hat, a generous overhang to pro• el, or pumice, the bags must be covered. tect the walls from erosion from the rain. The type of covering used will depend A coat that breathes, a plaster that allows mainly on the climate and on the design of the passage of moisture. the house. For example, a dome in a rainy This chapter applies to internal and ex• climate will require a plaster that is water ternal earthen plasters (often called "ren• resistant, such as lime, papercrete, or ce• ders," when exterior) for earthbag domes ment-stabilized soil. In extremely wet cli• and other types of earthbag houses, as well mates a waterproofing layer on the top as compatible finishes for benches, ovens, part of a dome or vault is essential (see the chart on page 77). If the water-resistent stoves, or any other earthen structures. Facing page:The Hart's In the earthbag construction system, render becomes saturated with water and dome covered with the wall surface is never the bare earth, but has no form of sealant or impermeable papercrete render. whatever material the bags are made out membrane, the moisture will go down with of. Rendering an earthbag house is neces• gravity through the earthbags. If the inte• sary for several reasons. rior is covered with an earthen plaster, this If the bags used for the construction are will quickly absorb water and come apart. polypropylene, they need to be covered On the other hand, if the house is designed

75 WEATHERPROOFING AND FINISHES 76 77

with a conventional roof and wide over• (water-thirsty) properties, and then re• hang, and is raised up from the ground by leased to the outside. There may be no the foundation and stem wall. The walls do other building material capable of regulat• not need a water-resistant render, being ing moisture levels as effectively as clay, protected from the driving rain, and an which continually absorbs and releases earthern render can be used externally. moisture in response to the humidity of If the bags used are made out of burlap the home. With thick and solid rammed (hessian), they will also need to be covered, earth, adobe, or cob, an external render but they have a longer exposure life than may not be necessary. polypropylene. In Devon, traditional cob houses have Another reason for rendering the exte• survived for centuries without any plaster rior of a wall constructed out of earthbags coating (they say it takes one hundred is that the surface has many grooves and years to wear away one inch of cob). Pro• Finishes for earthbag seams that in some extreme weather con• vided that cob walls are protected from domes and walls. ditions can be penetrated by rain, which actual erosion caused by the abrasion of Meanwhile, among the disadvantages They can be applied in two or more stages. must be prevented of course. The grooves driving rain, there is no necessity for exter• of earthen plasters are that they have a low The purpose of the first layer is to fill in can be extremely useful when applying a nal render, because moisture will evapo• structural resilience, therefore the design large gaps and crevices and to build up the render, however, providing a "key-in" area rate very quickly from an exposed cob sur• of the house is critical. If they are made main bulk, creating a fairly even surface for both external and internal plasters. If face. With earthbag construction, how• with earth that possesses a high clay con• for the smoother plaster to go on. This for aesthetic reasons the ribbed pattern on ever, rendering the external surface is a tent, or with very fine sand or silt as the first layer contains straw that is either un• the wall is desired, a render can be sprayed necessity, as emphasized above. filler and little or no straw, the plaster may cut; direct from the bale, which provides on, retaining the pattern of the bags. Among the advantages of earthen fin• be easily eroded. Also, earthen plasters are an interwoven stability; or finely chopped, For earthbag ishes are these attributes: affected by frost in cold climates; if mois• which is easier to mix in larger quantities houses with EARTHEN PLASTERS ture is allowed to penetrate the surface, it and is also great for building up thickness. conventional will expand and contract as it freezes and roofs providing If any plaster is used on a bare earthen wall • moisture-control Long straw in the mix creates a plaster- thaws, breaking up the plaster. In cold ar• appropriate that contains clay, the plaster should be a • fire-resistance reinforcing network and helps to fill out eas it is a good idea to cap the earthen plas• overhangs, no coating that breathes, allowing any mois• • odor-absorbent large holes or build up bulk where it is ter with a lime plaster. waterproof layer ture that enters the wall to escape. Earthen • nontoxic needed, as in sculpting the sills around is needed. plasters have been used extensively in • when dry, are unaffected by frost In locations where the plaster finish is windows. many countries for many centuries. As • aesthetically pleasing steadily eroded by weathering, it has to be An earthbag wall contains indentations well as being used as a finish coat for maintained on an annual basis. This can between the courses of tamped bags, mak• adobe, cob, or straw bale they also make an Earthen walls covered with earthen be turned into a fun ritual. ing it easier for the plaster to "key into," excellent covering for earthbag walls that plaster may give the impression of having or adhere. No plaster-reinforcing lath is have a roof overhang. With earthen plas• grown out of the landscape. Their subtle APPLICATION necessary, as this can interfere with the ters, whatever moisture does penetrate colors, complementing those of the Earthen plasters are incredibly flexible to earthen plaster being keyed into the wall. into the walls will be absorbed automati• ground that surrounds them, can add work with, allowing everyone to find a A good plaster mix is already well rein• cally by the clay, due to its hygroscopic greatly to the charm of the countryside. personal way of mixing and plastering. forced by straw. As this first coat of plaster WEATHERPROOFING AND FINISHES 78 79

is applied, it should not be smoothed out As explained below, if an earthen plas• with fibers, or adding lime, bitumen, or be reused (see the diagram on page 81 too much, but instead left rough, or into ter is well mixed and contains a good dis• cement." (Houben & Guilland 1994) When showing the lime life cycle). finger-sized holes so that the next layer of tribution of clay, aggregate, and straw, choosing the best stabilizer for a particular In industrialized societies, an increas• earthen or lime plaster will adhere. If the adding stabilizers can be largely avoided soil, many factors such as the clay content, ing number of people have been affected plaster does not stick to the wall, pound through design features. But earthen walls acidity, and texture must be taken into ac• by "sick building syndrome," which is a wooden pegs into the grooves between and plasters must be stabilized if the count, and many samples- must be made form of poisoning harming people who courses; these can also be inserted during earthen mix does not produce enough prior to construction. Again from live and work in buildings with insuffi• construction. binding strength (that is, does not contain CRATerre, "It is particularly unfortunate cient ventilation in which toxic vapors are that many practitioners of systematic sta• The second coat of earthen plaster is enough clay). Yet remember, houses built given off by artificial, chemical-intensive bilization do not know, or do not appreci• more refined and can be very thin, just out of earth need to move slightly over building materials and paint. Cementi- ate the original characteristics of a soil, and enough to allow a final smoothing out. time, and they are especially sensitive to tious finishes release carbon dioxide, a start about stabilizing soil with undue This can be a mixture of finely sieved sand dampness and temperature, so they need greenhouse gas, as they cure. Over the haste, when it is not particularly useful." and clay and, if desired, finely chopped to breathe, releasing moisture. Modern longer term, they seal in moisture and The wrong stabilization may do more straw, along with wheat flour paste or an• stabilizers and sealants result in severe therefore can cause air-quality problems harm than good. other stabilizer. damage to earthen buildings, because they and propagation of mold. tend to restrict movement and permeabil• As a case in point, cement can be a real Cement is also a more expensive mate•

STABILIZATION AND ity to moisture. Lime-based or other natu• enemy of earth architecture, apart from rial, because it contains higher levels of

ALTERNATIVES ral stabilizers do allow the walls to breathe the few selected applications such as bond embodied energy, although unfortunately Stabilizers are generally used to make ren• and move, adhere much better to earthen beams on top of walls, compression rings in some countries where demand for lime ders or plasters more durable and resistant walls (not requiring chicken wire or stucco in domes, and stabilization of sandy soil is very low (as in the United States), the to moisture. They are the "glue" that can be netting), and produce more porous fin• when making soil cement, which can be healthier option can be as expensive as ce• used to bind filler particles such as sand, ishes than Portland cement, the most applied as a render to earthbag domes in ment. The benefit of lime is its superior earth, gravel, or fibers such as straw. Stabi• widely used industrial stabilizer, which is areas with high rainfall. But cement should quality, and when properly applied it is lizers can be used as additives to earthen an expensive and environmentally contro• never be applied on top of an earthen plas• worth every additional effort and expense. plasters if the earth mix does not contain versial material, as discussed below. ter, as this will eventually crack and peel Sources of stabilization include: enough clay to provide the binding force It is possible to improve the characteris• off. As a general rule in earth architecture, and moisture resistance required. tics of many types of soil (especially sandy never place a hard, modern, nonbreathing • vegetable stabilizers material on top of a more flexible surface, Stabilizing earth is a very complex pro• soils) by adding stabilizers. These stabiliz• • processed natural binders as this will never form a solid bond and will cess, since not all stabilizers are effective ers can be used in the earthwalls them• • animal stabilizers eventually separate, as well as create con• with all soil types, and there are many fac• selves or in their skin as a surface protec• • mineral stabilizers densation and other moisture problems. tors that influence compatibility, includ• tion. Due to the vast variety of soil types, ing clay content, soil particle size and type, stabilization is not an exact science, and Buildings constructed of local stone, If a house is built in rainy or damp cli• pH balance, and climate. Other factors research is continuous. According to CRA- earth, and lime cause far less environmen• mates, the walls could be prone to severe that must be taken into consideration are Terre's Earth Construction, "The best tal damage than concrete and steel. Earth weathering from driving rain and frost. the type of application and the reliability known and the most practical stabilization and stone are reusable, and old, dry lime With effective planning and the right de• of periodic maintenance, as well as aes• methods are increasing the density of the render is chemically limestone again, just tailing, originating all the way back in the thetics and cost. soil by compaction, reinforcing the soil as when it was first quarried and can also initial design and building process, it may 8o WEATHERPROOFING AND FINISHES 81

be possible to forgo the use of stabilizers inches away from the wall to allow for ven• the whole question quite satisfactorily. As the CRATerre publica• and instead use a plaster made of just tilation. tion Earth Construction explains, earth. Adobe walls are traditionally protected There are several ways to protect by earthen plasters that are annually there is clearly a tendency at present to the over systematic earthen walls without using lime or Port• "topped up," but allow the wall to breathe. use of stabilization, which is regarded as a universal panacea land cement for stabilization. During the This can also be applied to earthbag as well for all problems. This attitude is unfortunate, as stabilization design and detailing process, familiarize as straw bale houses. Other ways of mini• can involve considerable extra costs, ranging from 30 to 50 yourself with the direction of the sun and mizing the penetration of moisture in• percent of the final cost of the material. Furthermore, driving rain, and plan accordingly to pro• clude sealing the earthen plaster with oil or stabilization complicates the production of the material. It is vide a roof with a large overhang (a mini• whitewash (see list of sealants starting on thus advisable to insist that stabilization is only used when mum of 18 inches or 450 millimeters on the page 92); stabilizing the earthen plaster absolutely essential and that it should be avoided where least problematic side). Extra-large porches with lime, wheat-flour paste, or other economic resources are limited. can be integrated into the house layout on plant, animal, or mineral stabilizers (see the sides that are most vulnerable from the list starting on page 81); or putting a wind-driven rain. The more protected the final cap of lime—a more durable, but still Vegetable Stabilizers walls are, the less protection that plaster breathing surface, over the earthen plaster. The following vegetable-based materials will serve as effective sta• needs to provide. Remember, each wall can Prior to any construction, it is crucial to bilizers for earthen plasters: be slightly different; the most exposed wall know your soil. See chapter 7 for a discus• can be the only one capped with lime plas• sion of soil-testing methods. • oils—coconut, linseed, and cotton, which need to be in ter. Always slope surfaces away from the Stabilization is not compulsory. If the "boiled" form to speed up the drying process ground around the base of the house as soil contains enough clay, you can ignore • juice of banana leaves, precipitated with lime, improves Harvesting prickly pear cactus. well as sculpted windowsills, alcoves, or erosion resistance and slows water absorption seating to shed the water. Design these to • prickly pear juice (found in the southwestern United extend out at least 2 inches (50 mm) from States) the wall, with a drip edge (see the diagrams Caution! • wheat flour paste, or any starchy material

on page 61). Temporary screens could be Stabilizers function as binders in the

installed as necessary to stop the seasonal mixture but are not sufficient on their own. Linseed oil can either be brushed on the finished surface of an

rain, or to prevent melting snow from To make them solid and hard, they need to earth plaster, as is often done with the final layers of earthen floors eroding the walls, for example a bamboo be combined with other fillers, for example (see chapter 7) or can be mixed into the final batch of plaster itself. or willow screen. Or if bad weather is year- nonexpansive particles of soil such as sand, To make prickly pear juice, the cactus has to be boiled until very round, on the side where the most snow silt, gravel, or fibers. soft, then its juices squeezed out. The resulting soupy liquid is then settles or the strongest winds blow, a high Never layer a rigid, modern, non- combined with the clay and soil mix that is to be used for the plas• stone wall could be incorporated into the breathing material on top of a softer, ter finish. Like any other stabilizer, this has to be tested prior to use, base of the walls. Permanent screens could breathing surface. The layers will eventually as it reacts differently with different soils. separate. also be built to keep driving rain off the Wheat flour paste is an inexpensive stabilizer for earthen plas• Prickly pear cactus being boiled. wall, keeping a distance of a couple of ters that is used by natural builders throughout the United States. WEATHERPROOFING AND FINISHES 82 83

I learned it from Carol Crews of Gourmet To make casein glue to stabilize earthen samples before beginning to plaster an en• Adobe, while we were making clay paints, plasters, soak about 1 ounce (25 grams) of tire wall. and it can be applied like a paint to earthen casein powder and ¼ ounce (8 grams) of plasters or floors. It can be made using borax in enough water to form a putty (to LIME PLASTERS commonly available flour, as described on make casein, see page 98). The putty can Historically most buildings in the United page 96. then be diluted with water to a consistency Kingdom used lime for interior plasters To make a plaster without using lime or suitable for mixing with the soil ingredi• and exterior renders. Cob buildings, if clay as the binder, you can combine sand ents of the plaster. For more casein recipes rendered at all, were traditionally covered with manure and wheat flour in the fol• see the end of this chapter. with a lime-based render applied directly lowing proportions: to the cob. This render consisted of lime, Mineral Stabilizers: Lime An earthen house with partial lime render, Peru. which serves as the binder, and sands and/ 4 parts flour paste (see page 96) For thousands of years in Europe, lime has or aggregates, which provide bulk at low 3 parts sand been used as a mortar for stone or brick cost, and which control shrinkage. It is construction; as an exterior or interior ter or adobe mix that contains clay, be• 2 parts manure best to use aggregate that has a good range plaster, when mixed with sand; and when cause the lime and clay seem to "compete" of particle sizes. Other processed natural binders that mixed with water, as a white paint com• as binders. Ideally the mixture should turn Fiber—for instance, hair—was often can be used to stabilize earthen plasters monly known as whitewash. In the mid- into a creamy paste, which will result when added to the traditional mix to minimize when too little clay is present include nineteenth century, cement and gypsum it is dry in a finish that is more wear- and the shrinkage cracks that often occurred. wallaba resin; rosin from oily pine resins, unfortunately became more common water-resistant than clay alone, but in real• Cow hair was preferred, but was harder to obtained during distillation of turpentine; building materials. Lime was slower to ity this is rarely achieved due to variations obtain, so goat hair was frequently used. copal, made from tropical tree resins, build with, and required artisinal skills in the pH of clays. Therefore combining Some straw bale houses that are being ren• added in a proportion of 3 to 8 percent for and good climatic conditions during ap• clay and lime can make a crumbly mix, and dered in lime use straw as the fibers. sandy soils; gum arabic, from the acacia plication, but produced durable and at• when used for stabilizing a wall material Using lime plasters has several advan• tree; and molasses. tractive results. Lime plasters and finishes such as adobe, can reduce its compressive tages. When lime used in buildings has set, harmonized with seasonal changes in hu• strength. it turns back to limestone, which is chemi• Animal Products as Stabilizers midity and temperature, like clay prevent• The theory is that, since lime is alkaline, cally the same as the lime that is quarried, Among the most popular animal stabilizers ing an overly dry or wet atmosphere by it combines best with acidic soils. The in use today are the following: eggs, blood, evaporating away excess moisture or ab• higher the pH of the soil, the more lime is sorbing it as necessary, fostering a healthy reacts with limestone and casein (dried milk) as proteins; urine needed to stabilize it. Lime apparently carbon dioxide and manure, as uric acid; casein (dried living environment. Simultaneously, due does not react well with alkaline soils, CO2 to its alkalinity, lime does not allow the milk); and glue made from animal parts or therefore carrying out tests is crucial to heat causes carbon H2O growth of mold on the walls, therefore cre• finding out the soil's behavior. If the mix dioxide to escape byproducts. Termites secrete a chemically when drying ating healthier conditions in wet climates. active substance, and termite hills stand of earthen plaster and lime does not turn water evaporates The life cycle of lime. Using lime as the binder in renders, smooth and creamy, the addition of either Lime in Building up well to rain. Their soil can be mixed lime putty quicklime After with other soils for the production of plasters, and mortars works best when a more acidic ingredient such as manure by Jane Schofield (Fig.

H2O 108, p. 123) blocks that adhere effectively; perhaps this sand is the filler. Lime is not the most effec• or organic soil may help. But care needs to water is added soil would also stabilize earthen plasters. tive stabilizer to use with an earthen plas- be taken; always test the mixes by making WEATHERPROOFING AND FINISHES 84 85

since the water has been driven off, it be• tool for large quantities). As more quick• for a long time, which means many of the comes very "thirsty" and reacts dramati• lime is added, the mixture starts to boil particles in the mix will have already re• cally with water (even water in the air, or in and bubble. When that happens, stop add• acted with moisture in the air and carbon the skin or eyes). ing quicklime and keep stirring until the dioxide to form limestone, making them When the quicklime is soaked in water, mixture ceases bubbling, or else the lime inactive and therefore weakening the mix. it turns to slaked lime, due to hydration. will burn and be of lower quality. The bet• To make lime putty out of bagged hy- This process produces a lot of heat, as the ter the quicklime mix, the faster the hydra• drated lime, mix the lime with water in a mixture boils violently. This is known as tion process occurs. The mixture should bucket to form a paste, cover this mixture slaking. The resulting slurry is calcium be stirred continuously until all the lumps with more water, and put an airtight lid on are broken down, and until the mixture the storage container. Store for several hydroxide (Ca(OH)2), known as lime putty. has cooled down and is of a creamy consis• weeks before using. Make sure it does not When applied on a wall surface and tency. It can then be sieved through a 716- dry out by adding water to it occasionally. therefore exposed to air, the lime reacts inch (2 mm) sieve to take out the un- The longer it sits the better it gets. If this burned limestone pieces. bagged lime is not very fresh or of the best Slaking lime in Xochitl, Mexico. with the carbon dioxide in the air to form limestone again, that is, calcium carbon• The resulting mixture is lime putty. quality, mix 1 part of the resulting putty When left standing, the lime sinks and the with 2½ parts sand (instead of the 3 parts therefore it can be reused if the building is ate, (CaCO3). This happens as it dries on destroyed and does not involve any pro• the building. The water evaporates, and water sits on top. For best results it is rec• suggested below) to compensate for the cessing that will harm the environment. the lime hardens through carbonization, ommended to leave it to mature for at inactive particles. To further strengthen In terms of healthy-home consider• thus completing the cycle (Schofield 1994). least three months prior to any use to en• bagged hydrated lime, add some of the ations, lime plasters and washes usually sure that all the calcium oxide has hy- more expensive "hydraulic" lime, which prevent condensation and an overly dry Making Lime Putty (Slaking) drated, and the longer it sits the better it sets faster and is more frost resistant after atmosphere, because the moisture is ab• For this task it is necessary to wear protec• will be, though in Mexico we used it after sorbed and then given out, contributing to tive clothing, including gloves, goggles, only one month. While curing it must re• Earth houses with lime render on a street in Cuzco, Peru. higher air quality. Also, due to its alkaline and mask. Since quicklime is caustic, it can main in a sealed container to prevent it properties, lime prevents mold problems. burn your skin, and during the slaking from drying out, which is the carboniza• Caution! Lime is ideal for use both as an exterior process the mixture can spit violently tion process whereby the lime putty will Always add the render or as an interior plaster or wash. while boiling. turn back to limestone, losing its binding quicklime to The chemical process of obtaining lime It is recommended to use 2 parts water properties and therefore becoming useless water, never add involves heating calcium carbonate as a plaster. water to quick• to 1 part quicklime. 1,200° Lime putty made from quicklime is by lime, as this can (CaCO3 from limestone or shells to Slaking has to be done outdoors with a far a superior material to the bagged hy- cause an Celsius. This can be done in kilns (shells metal container, making sure it is not explosion! can also be heated in a pile covered with placed on any flammable material, be• drated lime available from garden supply cowpats and coconut husks). The heating cause the container will get extremely hot. stores, which when soaked in water pro• duces a putty that is generally not as good. causes carbon dioxide (CO2) and steam The water is poured in, then quicklime is The problem with the bagged material is (H2O) to escape, and quicklime, or cal• added slowly to the water, with one person cium oxide (CaO), remains. At this stage, stirring at all times (a backhoe is the best that it might have been sitting in the shop 86 WEATHERPROOFING AND FINISHES 87

just three days instead of two weeks. A particularly recommended, because then When preparing the plaster, it is important Knock off any lumps around the score good compromise is 1/3 hydraulic lime to 2/3 the filler binds especially well. If sea- to mix and beat the lime putty for a long marks and spray the first coat with lime- hydrated lime. dredged sands are used, they require wash• time on a wooden or plywood surface with water before re-coating. When the second ing several times in clean water to remove wooden mallets and posts to get it to be• coat is hardening, it may be worked over Making Lime Plaster or Render salts. come more plastic, and then work it well again to improve the finish, remove any In order for a lime plaster to dry and be• The most popular proportions of lime into the sand. The more you mix, the bet• rough spots, and push closed any small come limestone again, it needs to give off putty to sand is: ter the plaster. cracks. More detailed instructions can be all its moisture and draw in carbon diox• found in the book Lime in Building: A ide; therefore, it cannot be applied in thick 1 part lime putty to 3 parts sand Application Practical Guide by Jane Schofield (see the layers. When applying a first coat of lime to Make sure there is good adhesion between bibliography). an earthbag surface, much crushed aggre• the lime and the earthen plaster under• Protect the plastered surface from sun, gate or straw needs to be added to allow for neath. (Remember, before the earthen wind, and frost to prevent it from cracking Caution! drying in the deepest areas keyed in be• plaster dries, to scratch its surface and during the drying process. It needs to dry • The durability of lime depends upon the. tween the bags. It is therefore better to first make finger-sized holes for "keying.") Tra• slowly. Ideal conditions are humid, cloudy quality of lime and the right mix, as well cover an earthbag wall or dome with ditionally lime-sand plasters have been days with virtually no wind and a slight as the quality of the application and the applied in two coats of not more than 10 drizzle. One way to provide protection earthen plaster to fill in those deepest drying conditions. Variables in the mix of millimeters thickness each. When apply• from the sun is to hang wet cloths a few voids before applying subsequent coats. lime and sand—including proportions ing lime plaster, the earthen plaster (or the centimeters away from the plastered sur• Lime plasters can vary enormously, de• and the particle sizes—are crucial, as are pending on the type of lime, aggregate, the weather conditions during the earth wall) underneath must be fully dried face. Frost can also be very damaging dur• and particular use. The proportions of application process. out then slightly dampened to help the ing the drying period, and frost protection lime to sand may vary between 1:2 for a • Apply in thin layers and make sure the lime grip the earthen surface. It is best to may be needed for a minimum of two smooth, fine finish to 1:5 for a rough first plaster is well keyed into the layer below. use limewater for this (made by dissolving weeks after the lime has been applied. coat. For greater strength in a plaster, the • If using lime to stabilize soil, always test 2 to 3 percent of lime in the water). sand particles used should be well graded, your mixture in advance. If not enough After application of the first coat it Pozzolanic Additives to Lime Plaster ranging from very fine to coarse in one lime is added, the compressive strength should be scored to provide key-in areas Pozzolanic material can be added, ground mix. can be lower than that of unstabilized for the second coat. This can also regulate up into a powder, to speed the setting of earth. As mentioned earlier, the only differ• the shrinkage cracks. Noticeable shrinkage lime and to help the lime mix set deep in• • Do not overwork lime plaster with a ence between the mix for interiors and ex• in the first coat can serve as a warning that side the wall, which is necessary when us• metal trowel. This makes lime come to teriors is the size of the sand or other ag• either the lime is too fresh, the mix is too ing lime as a mortar in stone or brick con• the surface and can form a hard crust wet, or the plaster is applied too thick; the struction, or as a render directly on top of gregate. A finer mix is best for the inside, over a softer backing, weakening the second coat should be thinner, as a safe• earthbag walls where there are deep inden• and a coarser for the outside—from very plaster. guard. tations. Some examples of pozzolanic ma• fine dust to as large as 3/16 inch (5 millime• • Before application, make sure you cover terials are crushed clay bricks, clay tiles, ters) for interior plaster, and up to twice as all metal surfaces, as the lime can stain. The second coat should be applied large for exterior renders, which should be • Do not put lime plaster on top of when the first is "green-hard"—that is, too shales, potash, and pumice. Pumice is a angular in texture to reduce the penetra• gypsum, wood, or latex. hard to dent when pressed with a knuckle, naturally occurring pozzolan from volca• tion of moisture. Limestone aggregate is but soft enough to mark with a thumbnail. nic areas. These pozzolanic materials WEATHERPROOFING AND FINISHES 88 89

speed up the setting of lime due to the re• phalt are bituminous. The use of bitumen clay with pure linseed oil and applying it active silica present in them, which com• as a stabilizer is very ancient, dating back at onto earthen plasters. Recipes for Lime Mortars, Renders, bine with lime at ordinary temperatures in least to Babylon in the fifth century B.C.E., and Plasters the presence of water to form stable, in• where it was used for making mortar or STABILIZATION WITH CEMENT —from the Earth Building Association, Devon, England soluble compounds with cementing prop• laying unbaked molded bricks. Bitumen Cement should only be used as a stabilizer

Mortar for Bedding erties. The rate of reaction is increased by mixed with soil acts as a water-repellent, in plasters as a last resort in cases where the

(can be applied as a first coat to earthbag walls) increasing the fineness of the pozzolanic reducing penetration and surface erosion soil does not contain enough clay and

12 parts coarse sand material (Spence & Cook 1983). from wetting, therefore serving more as a other, more natural stabilizers aren't avail•

3 parts lime putty waterproofing element than a binder. It is able. For instance, if lime is not available, gauged with 1 part pozzolanic additive (for example, brick dust) STABILIZATION FOR most successfully used with granular soil, soil stabilized with cement can be used on

Roughcast Render: Backing and Finish Coats WATERPROOFING in which it improves durability, but is also polypropylene earthbags containing sandy 2 parts coarse sand In addition to the water-resistant layers on widely used with clay soils, for instance in fill with little or no clay. Cement interferes 1 part grit (up to 4 millimeter diameter) domes, extra protection is needed in ex• the manufacture of adobe bricks. Stabili• with the binding forces of clay; therefore, 1 part lime putty tremely wet climates. Imperviousness will zation with bitumen is in fact most effec• care needs to be taken when deciding on 1 bucket mix to ½ bucket of teased hair. Omit hair in the final help to reduce water erosion, swelling, and tive in a process involving compression, as the quantity of cement to be added to your thrown coat. Hair must be teased out with carding combs to shrinking when the plaster material is sub• in production of compressed clay blocks. soil; the higher the clay content, the more remove the large clumps. ject to successive wetting and drying To stabilize adobe, 2 to 3 percent of bitu• cement is needed. Somewhere between 3 Smooth Render cycles. For waterproofing an earthen plas• men can be sufficient, and sometimes as and 10 percent will probably be appropri• 1 part coarse sand ter, a material that is unaffected by the high as 8 percent is required. If used as a ate, but tests should be carried out to de• 1 part grit (up to 4 millimeter diameter) water that fills the voids, pores, and cracks stabilizer, bitumen either must be mixed termine the necessary quantity more pre• 1 part fine sand is required. with solvents or dispersed in water as an cisely (see chapter 7 for more informa• 1 part lime putty Bentonite clay is a material that is dis• emulsion. If used with soils containing tion). 1 bucket of mix to ½ a bucket of teased hair persed in the soil and that expands upon high proportions of clay, a larger amount If cement is used, commercially avail• Lime/Manure Render the slightest contact with water and pre• is required due to greater resistance to able Portland cement has the least embod• 1 part lime vents the infiltration of pores. This has re• mixing. To obtain an even distribution, ied energy (that is, it requires the least en• 4 parts wet cow dung (a few days old) cently been tried as a waterproofing layer large quantities of water need to be used. ergy for processing and preparation). It is 1 part sandy earth in living roof construction (see chapter 5), Solvents that can be used include diesel oil, made of burned lime and highly reactive Lime/Quark Render but its use is still at an experimental stage. kerosene, naphtha, and paraffin (a mix• silica. It introduces a three-dimensional 4 parts lime When used as a waterproofing layer, it ture of 4 to 5 parts bitumen to 1 part paraf• matrix into the soil and results in a filling 1 part fat-free quark (to make quark, see the recipe on page 99) needs to be weighed down with a large fin oil). of the voids with an insoluble binder, 10 parts sandy earth amount of soil, as it expands and moves Note that these solvents cannot be used which coats the grains and holds them in Tallow, an animal fat, increases water resistance and adhesion. with absorption of moisture. in the rain and are flammable. Also, bitu• an inert mass. Ten percent by weight of melted tallow can be added to Bitumen is a mixture of hydrocarbons men stabilization is not effective in acid, While a cement-stabilized render can in lime; this can also be replaced by linseed oil. and other materials, either occurring organic, or salty soils. some cases be used over earthbags, for in• naturally or obtained by distillation of A simpler, more natural weatherproof- stance soil cement or conventional stucco coal or petroleum. For instance, tar and as- ing solution can also be made by mixing finishes, never use cement plaster on top of WEATHERPROOFING AND FINISHES 90 91

adobe or cob walls or a nonstabilized render or earthen plaster acts more like allowed to simply give each house a thin earthen plaster! blotting paper, absorbing and releasing coat of earthen plaster or whitewash once As emphasized repeatedly in this chap• moisture relatively freely. In addition ac• a year, the buildings have to be carefully ter, when cement plaster is applied on top cording to the Devon Earth Builders, small and expensively repaired. of earth, it forms a brittle, rigid surface cracks may be closed by redeposition of As a general rule: Renders should have a that is impervious to moisture. The effec• soluble material from the lime or clay. permeability equal to or higher than that of tiveness of cement-based plaster is depen• Carol Crews of New Mexico's Gourmet the wall material. dent upon the rigidity of the wall beneath Adobe explains the large lesson learned at APPLICATION OF STABILIZED it, since the cementitious finish itself the famous St. Francis de Assisi Church in RENDERS forms a rigid, relatively brittle shell. An Ranchos de Taos: earthen wall continues to move over time; With the addition of some stabilizers the this is normal, and is even beneficial in When it was coated with cement render applied to the domed or vaulted seismically active areas. Due to the differ• stucco in 1967 this plaster cracked parts of the structure becomes more ent properties of cement and earth, tem• and allowed the moisture to pen• brittle, and cracks can occur through ex• perature changes and moisture cycling etrate deeply into the adobes, but pansion and contraction with extreme tend to produce cracking in the cement the relatively impermeable stucco temperature changes, as discussed above. render. These hairline cracks could be al• prevented the adobes from drying This movement can be controlled through most invisible, but once the waterproof out again. Large sections of the the fragmentation of the render mass. By finish is compromised, any moisture buttress had to be rebuilt, so the placing the render in small "patties," a tex• drawn in through these tiny cracks will be community has now gone back to tured finish can provide thermal variation trapped, unable to evaporate, and will the annual renewal of the mud throughout the whole surface of the struc• start wearing away at the softer material plaster, which not only keeps the ture, creating air movement due to the behind. Given enough time, big cavities church building in beautiful condi• temperature differential between the sun can be worn away, even across the whole tion, but strengthens neighborhood zone and shade zone within the render it• width of a wall. This would not be such a ties as well. (Kennedy 1999,95) self, never allowing the surface to overheat. problem if the damage were detected early As one side of a rounded patty heats up, the other cools down. This surface has Chunks of cement enough, as the wear is very gradual. But the It is surprising that even after experi• plaster cracking off an been used for centuries in African villages surface of the cement-based plaster does ences of this kind, the U.S. Uniform Build• adobe wall of the and is prevalent in nature, for example in monastery in Abiquiu, not wear very noticeably, therefore hiding ing Code continues to stipulate the use of the scales of a fish or the trunks of trees. Santa Fe, New Mexico. the problem until entire chunks of wall cement plasters on top of the adobe walls cave in or collapse. in several of the Pueblo Indian villages in Top: The textured, stabilized render applied to the waterproof layer (roofing felt) Application Such moisture damage is most likely to New Mexico. With cement-based renders, on a vault in California. occur where hard, modern materials are a great deal of work is still required for Once you have chosen the right stabilized Inset: Textured surface of a vault. applied as a finish to a building whose un• maintenance, but often the result is a mix (clay, lime, cement, etc.), apply a "scratch" coat to fill in large cavities and derlying structure is made of softer, more patchy surface, since repairs with cement Bottom: Fragmented "patties" of cement-stabilized soil placed directly on the flexible earthen materials. A lime-based plasters are usually visible. Instead of being create the desired overall shape. Leave any surface of the earthbag dome, California. WEATHERPROOFING AND FINISHES 93 irregularities in the surface so the second can be combined with perlite for a more There are two types of sealants: those coat has somewhere to key into. To lightweight, better-insulating mix. Pig• that form a skin or a shell, and those that achieve the bubbly effect, patties of stabi• ment can be added for a more colorful penetrate deeply into the earth. Sealants lized soil are placed like roof tiles, overlap• outcome. Gypsum can also be mixed with that form a skin or a shell are fine, as long ping each other, starting at the base (like lime putty to create a faster-setting plaster as they breathe (lime is an example of one laying tiles) and working up the structure. than lime alone. that does). The main problem with "skins" Stagger the cracks so water will run down As an alternative to two coats of con• is that they create a thin hard cap on top of the grooves (see the photo on page 91). ventional plaster for walls and ceilings, a relatively soft surface, which can be easily clay mixed with sand and fiber may be damaged under pressure. On surfaces INTERIOR FINISHES more appealing. (See chapter 7 for more where pressure is constantly being ap• There are many ways of finishing the in- on mixing clay plasters.) Clays come in plied—as on an earthen floor—the right sides of earthbag walls, but whichever many different colors, and beautifully col• choice of sealant would be one that pen• Interior of a cassita in method is used for the final coating, it is ored finishes can be achieved using only etrates deeply into the earth rather than Canelo, Arizona. The walls have a clay finish the earthy clay colors, for there is seldom a forming a shell-like surface. This is why, best to coat the uneven earthbag surface with mica for shine. The with an earthen plaster to fill in any large problem with the colors clashing. Mica when sealing an earthen floor with linseed white bench is cavities before the other layers are applied. can also be added to a final coat of clay oil, it helps to heat the oil to make it soak in plastered with gypsum. As discussed above, lime mixed with paint or plaster, which will add a glittering as deeply as possible. To encourage the oil very fine sand is a great material to use on texture. to penetrate even deeper into the floor, it top of interior earthen plasters. Another is Earthen plasters are usually applied can be thinned with various thinners (see Cedar Rose gypsum. Gypsum is a naturally occurring with hands or a wooden trowel, but for "Earthen Floors" in chapter 7). Good seal• demonstrating the ants include penetrating oils such as lin• spraying of a mud soft rock or powder. It is converted to larger projects you can use a hand-held mixture at the Natural "plaster of Paris" by heat. Gypsum is spray gun powered by a gas-driven com• seed, hemp, caster, or coconut, and animal Building Colloquium, readily available at building supply stores, pressor. Screen the mix through a 1/8-inch urine and blood, all of which oxidize and Kingston, New Mexico. and it can be applied directly on top of screen to eliminate any lumps that might harden the surface. earthen plaster, since it is breathable. Due clog the machine. This spray mix is often Certain sealants may be mixed and ap• to its softness, it can only be used on inte• made with wheat flour paste as a stabilizer plied as one layer, but different sealants rior walls. It doesn't shrink or crack when (see page 96 for the wheat flour paste should never be layered over one another, dry and sets very fast, which can be an ad• recipe). as they could be incompatible and peel. vantage or disadvantage—you need to Binders such as clay can also be used as a work fast when applying it to a wall, but SEALANTS waterproof sealant in their finer forms, the technique is not hard for nonprofes• Sealants can also be used as nonstructural but too much pure binder will not be du• sionals to learn. Gypsum is acidic, and has stabilizers, but they are called sealants be• rable. Filler (sand, silt, or gravel) should be a low embodied energy compared to Port• cause they seal the earthen plaster—that added to it to make it solid and hard. land cement, but in premixed form it is is, they are not mixed into the plaster dur• Sodium silicate dissolved in water is relatively expensive. Gypsum plaster can ing the construction process but are ap• known as water glass. Water glass can be also be mixed as 1 part gypsum to 2 parts plied like a paint or a finish plaster once used as a sealant with certain soil types, but sand for more texture and lower cost, or it the original plaster has dried. has been known to react very differently WEATHERPROOFING AND FINISHES 94 95

layer. Potassium silicate is made out of als in combination with poor ventilation; this phenomenon can quartz sand and potash and binds itself damage the health or at least affect the comfort and performance chemically with silica when applied, which of people living and working in newer buildings. is good for surfaces that contain sand. Sili• Like cement, modern waterproof masonry paints, emulsion cates also bind mechanically in grooves in paints, and vinyl wallpapers all slow down or prevent the evapora• the surface of the plaster. tion of moisture from the wall, which often leads to the render or Before applying, thin silicates with wa• paint separating from the surface of the wall, and water trapped ter: for example, 1 part potassium silicate between the wall and the paint can be harmful to the wall itself, to 5 parts water. especially if the building is constructed of materials such as wood or earth that can deteriorate when wet. PAINTS Paint consists of pigments, extenders (also known as fillers), and As well as plastering earthen walls on the binders. Pigments and extenders comprise 75 percent of the total inside, you can coat them with "breathing" quantity of paint. Binders comprise 25 percent. Pigments color the paints to give extra protection or color. I filler. They can be different minerals or plant powders. It is better learned about this subject from Swiss to use water-based paints on walls, because these allow for vapor

The Steens' residence, with varied mixes of earth. It is not suitable painter Reto Messner. Natural paints de• diffusion and breathability. Extenders are a kind of paint "filler." Canelo, Arizona. for clay soils, but has proved useful with rived from plant and mineral materials Extenders can include whiting, obtainable at paint or ceramic sandy soils. Sodium silicate is fairly cheap have subtle colors, pleasant scents, and stores; barium sulfate; kaolin; marble dust; chalk; and diatoma- and is available in many parts of the world. help create a healthy indoor environment. ceous earth. It acts as an impermeablizing agent after a Since only a few decades ago, the petro• Binders can be water based or oil based, depending on the re• curing period of seven days. It is soluble in chemical industry has largely taken over quirement. Examples of water-based binders include clay; casein water, but can be rendered insoluble by al• production of oil-based and water-based (milk protein), which is very strong when dry and will not come lowing it to react with slaked lime. Thin paints. They not only abandoned the tra• apart; water glass; lime cellulose glue; starch glue (corn starch) or sodium silicate with water prior to mixing ditional view of paints as a breathing skin, wheat paste; and lime. with earth, otherwise too many "micro fis• but have also introduced synthetic chemi• Limewash, also called whitewash, is a water-based paint that has sures" will result, causing a strong suction cals that can be very harmful to us. In ad• been used for centuries, ordinarily re-coated every year or so. Ad• of water. Another silicate used to make dition to being concerned about the pollu• ditives to limewash to make it more durable (but less breathable) plasters impermeable is potassium silicate. tion generated by industrial paint manu• include linseed oil, tallow; and proteins such as egg white, blood Painting with clay paint over an earthen plaster on a Potassium silicate can be dissolved in wa• facturing, increasing numbers of people plasma, or casein. See page 97 for a more detailed discussion of straw bale wall in Casa Chika, Kingston, New Mexico. ter to make a liquid, then used to seal and find themselves affected by the vapors lime paints. waterproof mud plaster. The coating is given off by modern paints as they dry, clear in color, allowing the full beauty of and even by the low levels of volatile or• CLAY SLIP OR ALIS the plaster to show. When put on top of ganic compounds (VOCs) that continue Alis is a clay-based paint traditionally used over earthen plasters on lime plaster, potassium silicate reacts with to outgas afterward. Sick building syn• the interior of adobe houses. Alis can be of any desired color, and the calcium in the lime and the carbon di• drome has now been widely recognized to when dry it makes a durable finish. I learned about alis from Carol oxide in the air, creating an impervious be the result of modern synthetic materi- Crews of Gourmet Adobe in Taos, New Mexico. 96 WEATHERPROOFING AND FINISHES 97

pancake batter. When the pot of water is fine kitchen sieve. If pigment is desired, be vigorously boiling, pour in the flour-water Application sure that it is thoroughly premixed by add• mixture to make the pot almost full, and Before application, make sure the wall sur• ing it to a little warm water in a jam jar, stir the mixture well. face of your earthen plaster is totally dry, as then seal the jar's lid and shake vigorously. It should thicken immediately and be• any moisture could leave water stains in Add the pigment to the limewash, and stir come translucent. Take it off the heat. the finish. Start applying the paint with a and sieve it again. To get a really white fin• The total proportion of water to flour brush at the top of the wall so you do not ish over an earthen plaster, you will prob• should be about 6 parts water to 1 part get drips. ably need at least three coats. Limewash flour paste. For mixing the plaster dilute Most walls require two coats. Make sure turns very white only when it is dry, and if this wheat paste to a good consistency. the first coat is completely dry before the pigment has been added, the final coat will second is applied. When the second coat turn about seven times lighter than when Natural To Make Alis Clay Paint An earthen plaster becomes "leather hard," take a damp it is liquid. Always wet the surface of the Putty shower wall painted Fill a 5-gallon bucket three-fifths full with earthen wall before applying a limewash. (squeezed-out) sponge and a bucket with Mix chalk and with lime, Canelo, 3 parts water to 1 part cooked flour paste. warm water and start to sponge the wall in linseed oil, and Arizona. For the first, slightly thicker coat, add circular movements. This will smooth out Additives to Limewash knead until well to the diluted flour paste liquid a mix of 3 the brush strokes and clean the paint of These include: stirred and stiff. If white alis is desired, Carol uses white parts clay to 2 parts mica to 1 part fine sand. any pieces of straw or flakes of mica that • casein glues, or flour paste, as Add earth or kaolin clay as the binder, because it is inex• (If no mica is available, substitute fine might have been added to the mix for spe• binders plant pigment as pensive and can be purchased in large bags sand.) Keep adding these proportions un• cial effect. When the sponge begins to feel • salt, to improve durability desired, and use from a pottery supply store. She uses til the mixture is the consistency of heavy dry, wet it and squeeze it out again. When • molasses, to increase penetration for filling gaps ground mica in a fine powder form or fine cream. you are finished, you can save the leftover into an earthen wall and puttying windows. sand as the extender, and straw or mica For the second coat, add to the diluted paint for later repair to any minor damage • alum, to improve adhesion flakes for added texture and glitter. To flour paste a mixture of 1 part clay to 1 part by drying it out on a tarp in "cookies." To • linseed oil or tallow, to increase make the paint thicker, especially in the mica. Again, keep adding these until the reconstitute, simply add water to the dried water resistance first coat, a small amount of fine sand is mixture is the consistency of heavy cream. paint until the appropriate consistency is added to smooth out irregularities in the A little powdered milk (with casein) obtained (Kennedy 1999, 93). Recipes for Water-Resistant Whitewash plaster surface. As filler, Carol uses cooked will thicken the mixture and makes it Whitewash with oil or tallow. For exterior flour paste in a proportion of 20 to 25 per• somewhat tougher. Some finely chopped LIME PAINT OR WHITEWASH surfaces, the addition of linseed oil or tal• cent of the liquid. Pigments or colored clay straw or large flakes of mica can be added If possible, find a source for ready-made low (animal fat) makes the whitewash can be added to white alis to give it color. for an interesting texture. Colored clays or lime putty (matured for a minimum of six more resistant to water. According to "Ap• pigments may also be added to create dif• weeks), as this is the easiest, safest way to propriate Plasters, Renders and Finishes To Cook Wheat Flour Paste ferent colors. If colored clays are added, buy the material, or mix bagged hydrated for Cob and Random Stone Walls in De• Set a pot two-thirds full of water to boil on they can replace some or all of the kaolin in lime. Limewash is lime putty and water von," published by Devon Earth Building the stove. In a mixing bowl, whisk together the recipe. If mold is a problem, it is advis• (see page 84 for more on lime putty). Mix Association, use no more than 1 table• another one-third proportion of cold wa• able to add some dissolved borax powder, the putty and water together to a consis• spoon of linseed oil or tallow for 2 gallons ter with some flour to a consistency of a which will make the paint alkaline. tency of skimmed milk. Sieve through a of whitewash. Add the oil when the lime 98 WEATHERPROOFING AND FINISHES 99

pound clean glue in water, and add this and water are slightly heated. Continue 1 resistant. When it is mixed with an alkaline Mix together ¼ cup (2 ounces) casein stirring and heating slightly until the mix• solution to the mixture. You may also add substance such as borax, it will react and powder with 3 ounces of warm water, and ture has blended. coloring matter to give the mix any shade form a gluelike solution that can be used as ideally let sit for two hours or overnight. you please. Apply the limewash while still a binder in paints or plasters, or as an ac• (If homemade quark is used, it does not Whitewash with linseed oil and milk. To warm, with a whitewash brush—except tual glue (see page 98). If the casein paint is need to be mixed with water.) Mix the increase the water resistance of white• when particular neatness is required, in used on top of lime plasters it does not casein solution with ½ cup (4 ounces) of wash, fill a container with 4 quarts of which case use a paintbrush. need to contain borax, as the alkalinity in borax dissolved in ½ cup (4 ounces) of milk, add 1½ cups of linseed oil, and stir This recipe is from a book by Sam the lime will activate the casein. warm water to produce the binder mix• well. Add lime and stir continuously un• Droege first published in 1861 and found Casein can be purchased. One com• ture. (Borax is an alkaline soap; do not til the mixture is creamy, of a paintlike on the Internet (see the bibliography). mercial brand is called Auro (see the re• dump in your garden.) This mixture will consistency. To make whitewash that will not wear sources list). You can paint your house us• become a sticky paste and is also know as off, make the whitewash in the ordinary ing about 2 pints of casein, as it goes a long casein glue, which will lose strength over Some Old Limewash Recipes manner, but then place it over a fire and way. You can also make your own casein time and must be kept refrigerated. If you are interested in trying out working bring to a boil. Then stir into each gallon a with simple ingredients. To this casein binder add 8 cups of wa• with lime in a more primary form instead tablespoon of powdered alum, ½ pint of To make casein (also known as quark or ter and mix until the solution is like pan• of premix, here is a recipe for a brilliant good flour paste, and ½ pound of glue dis• milk curds) at home for use as the binder cake batter. This can be used as a durable whitewash that will not rub off, and which solved in water while it is boiling. in paint: glaze or paint. (The binder mix when di• bears a gloss like ivory. Take or quarts This wash looks as good as paint, is al• 5 6 Mix 1 quart nonfat or 2% milk and 2 luted can also be used to mix a durable clean unslaked lime, slake with hot water most as durable as slate, and will last as teaspoons low-fat sour cream. Stir well. plaster.) When making transparent paint in a tub, and cover securely to keep in the long as paint. The recipe comes from the Let sit in a warm spot for two days until it (a glaze) for use on top of a lime plaster, steam that's generated by the slaking. Building Biology and Ecology Institute of thickens or curdles. (If it does not curdle, you do not need to add borax, since the When the lime mix is ready, pass it New Zealand (see the resources list). warm it up or add vinegar to make it lime will activate the casein. through a fine sieve, and add ¼ pound curdle.) Separate the curds from the whey To make this glaze into an opaque paint, whiting, 1 pound good, pulverized sugar, CASEIN by pouring the mixture through cheese• mix pigment with an extender such as and 3 pints rice flour, first made into a thin Casein can be used as a binder or stabilizer, cloth placed in a sieve. chalk or any other inert white powder to paste. Boil this mixture well, then dissolve to make paints more durable and weather What you have left is known as quark, make a paste. Then add this mixture to the which contains 7 to 12 percent casein, the binder in a ratio of 25 percent binder to 75 right proportion for use as binder in the percent extender with pigment. paint. Do not leave this mixture to stand You can also make a water-based casein for too many years, as casein loses strength Casein Glue emulsion that is more water-resistant us• with time. ing quark and lime. Mix a quantity of Here is an old recipe for casein glue.

Mix skimmed-milk curds (quark) well with 2.5 percent quicklime. Use after one hour. Apply to skimmed-milk curds (quark) with about Recipe for Interior-Exterior Casein both surfaces to be glued together and set under pressure for twenty-four hours. The mixture 20 percent lime to obtain casein glue, then should be remain useable for about three days on wood, cork, paper, or heavy wallpaper. To make a durable casein glaze or paint thin with water until it becomes a creamy that can be used inside or outside and not brew. This can be used for several days. wash off in the rain: Add 2 to 3 percent linseed oil to increase 100 WEATHERPROOFING AND FINISHES 101

adhesion and durability, especially for ex• is reasonably water resistant, but if ex• Remember, cement plasters are very der, therefore it might not crack as much terior application. In addition, you can posed for a long time to moisture will brittle and will tend to crack due to subtle and may be easier to apply and repair. also use diluted casein paint as a primer, eventually deteriorate. movements of the whole structure, there• The wear of the finishes is affected sig• which will increase durability further—no To make oil-based casein paint, add oil fore requiring repair. Repairs of cement nificantly by the materials you choose, the wiping off after only a few weeks. Another to a casein binder (see the recipe above) stuccos and renders will always be visible quality of the application, the location of way to improve the adhesion of this paint very gradually, as in making mayonnaise. unless the whole area is repainted. the house, as well as the overall design of is to add honey to 100 parts curd, 50 parts Mix a maximum 25 percent of volume of Papercrete (fibrous cement made of cel• the house and whether there are any chil• water, and 20 parts lime. oil into the mixture; 15 percent is usually lulose mixed with cement or lime; see chap• dren or animals around, in which case good, so test the paint on a sample patch ter 1) can also be applied as a plaster directly more house maintenance is generally nec• Application before more oil is added for shine. The on earthbags. Papercrete is still at its ex• essary. Annual replastering does not have If casein paint is sucked into the plaster mixture will eventually start to get creamy. perimental stage, but this seems to be a to be a chore, but can be turned into a fun right away and the desired effect is to be a To make casein- or oil-based limewash, material that is water-resistant (not water• social event involving the whole family or glaze, it is necessary to prime the wall first mix 1 ounce limewash (lime putty mixed proof), therefore suited to most climates; even the neighborhood. with a thin mixture of casein binder and with water) and 5 ounces casein powder or insulative; and not as brittle as cement ren• water, and allow it to dry. When the paint is 1½ ounces linseed oil. applied the water in the paint should be Paint this limewash onto fresh lime absorbed, but not immediately. As a prim• plaster that is not totally dry. You must use ing binder, alum is especially appropriate thin coats. It is best to use linseed oil for the for gypsum-plastered walls. If the paint first coat, followed by casein, because casein continues to dust off, it does not contain limewash is harder than oil limewash. enough binder, or the wall is not primed properly. Too much binder can create a MAINTENANCE glassy surface, which can flake off. The annual maintenance requirements for a plastered building depend on the nature OIL-BASED PAINTS of the finishes that were used. If the plaster Linseed oil (from flaxseed) is a good oil to finish is made of earth, maintenance is re• use in oil-based paint. This is a "stand oil," quired at least every two years. A thin coat which is an important factor in making of earthen plaster should be reapplied on a oil-based finishes, because it oxidizes— dampened wall surface. This is best carried and dries—when exposed to oxygen. Ac• out during the summer months. If earthen cording to the Canelo Project's Earthen plaster has been sealed with a capping of Floors booklet (see the bibliography), in lime plaster, an annual fresh coat of white• the "old days" oils were left to stand ex• wash will maintain the finish well, but this posed to the air to produce the drying ef• is not absolutely necessary, as well-ex• fect. However, they can now be produced ecuted lime plasters will last many years by injecting oxygen into the oil. Linseed oil before they need to be repaired. 7

OTHER INTERIOR WALLS, FLOORS, AND FURNISHINGS:

BUILDING WITH CLAY

nce the structure of an earthbag adapt to any shape. In a circular earthbag house is complete, it is possible dome shape, where straight and square Ofor the interior of the house to furniture can be difficult to accommodate have conventional furnishings, just like and expensive to custom-make, earthen any other house. More often, however, materials are more flexible and less expen• those who have gone to the trouble of find• sive, allowing you to design the interior in ing out how to build an earth house are in• a complex or simple way, using straight terested in using natural materials and lines or curves as desired. earth-based techniques for completing the interior, in order to create an especially FINDING AND ANALYZING healthy and beautiful home. This can in• BUILDING SOILS clude partition walls, ceiling treatments, As we consider guidelines for soil analysis insulation, floors, and furniture. In this prior to building with clay-earth mixtures, chapter, I refer to building materials and readers will once again appreciate earth- techniques such as clay-earth mix, straw- bag construction for its simplicity, as there clay, cob, and adobe, which were intro• is no need to understand the complexity of duced in chapter 1. In describing these the soil and its clay content, since the bags techniques, I emphasize the need for clay themselves provide a form to hold the as a binder, as this is the most crucial in• earth in place, whereas when building in• gredient when building elements that terior partitions, benches, ovens, and Facing page: Earth- must maintain their structural integrity earthen floors, the binder-to-filler propor• plastered shelving being constructed with tions are critical, because these structures without exterior forms. Clay generally straw-clay blocks and binds together filler materials such as sand, need to maintain their own form, with no carrizo decking. straw, and earth. bag or other exterior form to hold the The advantage of using earthen materi• shape. als for furnishings on the inside of a house Due to the vast variety of soils, there are stems not only from the beauty and health no universal recipes for making good clay- benefits of earth, but also its ability to based mixtures such as cob or adobe. You

103 BUILDING WITH CLAY 104 105

can ask the people who have already built dumping ground, which might be far away pebbles, will settle at the very bottom of should be made into small patties or adobe in the area where you want to build what and therefore incur extra charges. If you the jar. Then the sand and the silt (which is blocks for comparison. mixtures have worked for them. It is cru• can take this "waste" material off a a finer version of sand) will settle, leaving The first sample should be pure earth, cial to know your soil before using it for builder's hands, you may be able to obtain the clay (the smallest particles of earth) as to be used as a control, followed by samples construction. For this, homemade tests clay for a good price. Certain plants indi• the top layer. From this simple test we can with 10, 20, and 30 percent of added sand. can be carried out. There are several char• cate the presence of clay soils. For example, estimate the percentage of clay in the soil. Repeat the test, adding fibers such as straw, acteristics to look for, including particle the group of plants called horsetail or grass, hair, or textile strands, and then add size (ranging from fine silt and sand up to scouring rush (Equisetum) suggest clay Testing by Hand both fibers and sand in varied propor• rough aggregate such as gravel), plasticity soils (Andreson 1997. When the earth is There are numerous tests that can be car• tions. If the soil has a high clay content, you (the capacity to retain a shape, which per• very dry and many irregular cracks have ried out on soils to check if clay is present. may need to add more sand as a filler or mits sculpting of the material), compress• appeared on its surface, this indicates the Rolling and pressing the clay between the more fiber to inhibit cracking. ibility (to increase adhesion, especially presence of clay. This is easily seen at the fingers will give an indication if the soil When a sample indicates a good mix for important with techniques such as pro• bottom of puddles or dried-up ponds. contains any clay. If a thin "sausage" building, it will not crack. But not all duction of compressed adobe blocks), and Other landscape clues for the presence of (about ¼ inch or 4 millimeters thick) can cracks are bad. For adobe, the California acidity or alkalinity (which affects the way clay are described in Michael Smith's be rolled and does not crack very much Building Code allows cracks up to 2¾ various materials combine). book, The Cobber's Companion (see the when slightly bent, the earth contains high inches (7 centimeters) long and 1¼ inches Prior to beginning to build with earth, bibliography). quantities of clay. If it cracks, it probably (3 centimeters) wide (Khalili 1986). When it is important to understand the best ways The best way to begin to know your soil contains a larger quantity of silt. Another dry, a promising sample can be tested by of finding, extracting, and mixing the is by making several tests with samples. way to test soil by hand is to make an egg twisting it with your hands to try to break most resilient blends of clay and other shape, then crack it. If it resists cracking, it it, or by dropping it from knee height. If it materials. The soil should be obtained Jar Test is clay, whereas if it cracks easily it is does not break upon impact, then the from below the topsoil line (topsoil is for Pour several handfuls of earth into a large mainly silt or other more granular par• earth mix is right. gardens), and must be free of all organic glass jar half full of water. Shake the jar well ticles of soil. If the local soil does not contain enough matter. and let it sit until all the particles settle. clay to bind together properly, it is possible There are a number of ways to find clay. The heaviest particles, such as rocks and THE RIGHT MIX that stabilizers are required. These need to Many conclusions may be drawn from the A good construction material must have be tested at this stage by being added into geological situation. Purchase geological clay and sand in the right proportion. The the mixture in varying quantities. maps of the area or visit the geology de• more filler that is mixed with the clay, the To answer the question of what makes a partment of a university or a government more evenly distributed the cracks that re• good building mix, here are a few pointers, institution to request assistance. Consult -floating organic matter sult from drying will be. The more the although it is important to note that every water local brickmakers or potters, who are nec• clay straw is added, less sand may be needed, mix should first be tested by making small essarily very conscious of fine distinctions silt because straw takes up the shrinkage, samples and observing them when dry, sand among earthen materials. Investigate the gravel therefore stopping the cracks. prior to any application. availability of clay on conventional con• Always make samples, since this is one

struction sites, where clay is often dug up A jar test to estimate percentage of clay in a soil of the most effective ways of being sure of • To form a durable surface and create a during excavation and transported to a sample. your soil's limitations. A set of samples mix sticky enough to adhere, you may BUILDING WITH CLAY io6 107

need to mix more thoroughly, increase You will also want to carefully control According to Devon Earth Builders, the clay content, and/or add some the type and size of filler or aggregate that traditional English cob mix contains clay type of stabilizer. you use, taking into consideration the in• and aggregates in the following propor• • To minimize shrinkage and therefore tended function of the mix—for example, tions: cracking, you can reduce clay, add whether it is for the structure of furniture, more sand or other aggregate, keep the filling out or evening out of a base plas• fine course sand 25-30% water content as low as possible, or ter, or the final smoothing out of a finish silt 10-20% add more fiber such as straw and plaster. The finer the desired appearance, clay 10-25% other grasses, cellulose, or other plant the finer the added aggregate, filler, and fi• or animal fibers. bers need to be. It will also contain fibers (as much as • To increase water resistance as much Also, a more structural earthen mix can the mix can take without ceasing to ad• as possible and slow down erosion by have a large range of particle sizes, from here) to reduce cracking and increase the driving rain, you can add a good silt to gravel, as the filler material, and "fill• insulation value. Sufficient straw in the distribution of aggregate sizes, fibers ing in," "evening out" plasters can be made mix provides a level of thermal insulation such as straw, and/or stabilizers using more of the long straw additive in that is better or equal to the insulation in derived from plant, animal, or mineral order to be more reinforcing and provide many conventional houses. In England, sources (see chapter 6). more sculptural capacity. The final layer of traditionally the fibers used were wheat plaster can have just fine sand mixed in and barley straw along with hay, twigs, and • To increase the permeability and A cob shelter built with the clay, as well as finely chopped porosity of an earthen mix, which are other organic material including animal or cob for building is all principally the during a workshop led straw and stabilizers if desired. by Sunray Kelly and necessary to permit moisture to hair and animal dung. same process. The ingredients might vary Carol Crews, Rico, My own favorite mix for a thick first evaporate and to allow for expansion Correct mixing of the material is as im• slightly, but once the recipe for a particu• Colorado. of freezing water in order to avoid coat of plaster and for sculpting is quite portant as the actual construction process. lar type of earth is established, these pro• frost damage, an earthen mix needs simple and works with most clay soils. In a If too little water is added, the necessary portions can be used for any of the above a good distribution of aggregate, wheelbarrow (as described on page 108) distribution of clay throughout the soil techniques. The ingredients might include straw, and anything else that will combine a soupy mixture of clay soil with will be difficult to achieve, and the cob varying proportions of straw, depending create air gaps. as much long or chopped straw as the mix• lumps will be difficult to compact when on the coarseness of the earth and sand. ture can take and still stick together, along placed on the wall. In the past, compaction Earthen plasters or floor finishes will re• If you are carrying out sample tests with with just enough sand to give it some body was achieved using the worker's boot, so quire the mix to be sifted, for a finer finish. stabilizers and are not getting the results and prevent hairline cracks for the finish• that each cob is well heeled-in and thor• Cob for building may require more straw you might expect, try testing the pH of the ing layer. (Chopped straw will be easier to oughly trodden between each course. Ex• than adobe requires. manage than long straw during smooth• soil, as not all stabilizers react with soils of cessive moisture dilutes the soil to a Many different ways have been devel• ing.) If the first layer is fairly thick and all types. For example, if the clay is more porridgy state, making construction im• oped throughout the years in different even, the second layer can be thin, with acidic, it should react beautifully with possible; in such cases, more dry mix and/ parts of the world, but they all have the more sand substituted for straw, and in• lime, an alkaline, forming a more neutral or straw can be added. same aim—evenly distributing the vari• side the house a stabilizer such as wheat and creamy mix for an external render (see Getting the right mix for earthen plas• ous materials that make up the mix and paste added. chapter 6 for more on stabilization). ter, floors, or furniture and making adobe creating a moist, pliable mass of earth. 108 BUILDING WITH CLAY 109

In the traditional way developed over centuries in Devon, En• sieved, up to half an hour might be neces• loved activity, where not only the adults gland, once proportions are identified through testing and making sary. When the mix is ready, work it thor• but the children can all join in and have an samples, the desired earth mix is oughly with your hands, stirring around excuse to get muddy. And it is amazing to so that the sand, clay, and water are well see how quickly adults turn into children spread out in a bed approximately 100 millimeters in depth mixed into a soupy consistency. At this when working with "mud," especially for on a thin layer of straw. Water is then added and a second, stage, as much straw can be added as the the first time. Therefore to replaster your thicker layer of straw is spread evenly on top. (About 25 kg. mix can take and still cohere, kneading house once a year could turn into a huge of straw per cubic meter of soil—1.5 to 2.0% by weight—is thoroughly with hands or with feet. For party and an excuse to enjoy yourselves considered adequate.) The straw is then trodden into the foot mixing, dig a pit to use instead of a with your friends and relatives. soil, which is turned several times, more water being added wheelbarrow. as required. Thorough treading of the mix (traditionally by Another way of mixing, which I learned THIN PARTITIONS AND men or animals) is vital because it ensures even distribution at the Natural Building Colloquium, in• CEILING PANELS of the clay and renders the material to a consistency and a volves placing the earth mix in a pile on As an alternative to conventional gypsum state of cohesion suitable for building. The quantity of water top of a plastic tarp. Water is added, and drywall, extensive research is underway to used will vary according to soil type but is usually in the two people hold the tarp at opposite ends, produce structural members out of clay- range of 10 to 12% by weight. If too little water is added the leaning and pulling to each side, shifting fiber composites. Prefabricated fiber com• necessary distribution of clay throughout the soil, will be their grip on the tarp to roll the mixture posite board is a form of industrial dry- difficult to achieve. (Devon Historic Building Trust, 1992.) back and forth, and stopping from time to board developed in the past few years time to add more water and straw. This (Andreson 1997). This board is made of The Taos Pueblo way of mixing is similar to the traditional technique requires a substantial amount Mixing the clay. Devon way, except that the warm sunny summer weather allows of effort, but, as when mixing with feet, the people to do it barefooted in a dug-out shallow pit. your back remains straight, whereas mix• Athena and Bill Steen, while in Mexico working on the Save the ing by hand requires bending over a Children Foundation project, were taught by their Mexican col• wheelbarrow. Remember that the thor• leagues how to mix the "no-effort way." Simply half fill the con• oughness of the mixing contributes to the tainer you are mixing in with water (most likely a wheelbarrow), Mixing with bare feet. binding strength of the resulting mixture. then use a shovel to sprinkle the dry earthen mix into the water in An endless variety of mixing methods is the proportions you have derived from testing (or use pure clay). constantly being developed and refined, Make sure the distribution is even and not too thick. If the mix is each one suiting different climates and in• not ready, alternate shovels full of the necessary clay, earth, and/or dividuals. Ianto Evans and Linda Smiley of sand. Once earth covers the top of the water, go and have a cup of the Cob Cottage Company, who have de• tea or a lunch break. Let it sit long enough for the soil-clay mixture voted the past several years to the revival of to absorb all the water. The speed of absorption depends on the cob in the United States, believe that you fineness of the clay-soil particles (for instance, whether it has been should always mix cob when happy. This sieved). After a few minutes, test the mix by sticking your finger way the building is built with good as op• in. When ready, it will be smooth and creamy. If it is still lumpy and posed to bad energy, enhancing its quality. hard, or partly dry, it needs to sit longer. If the soil has not been Mixing earth usually becomes a much- BUILDING WITH CLAY 110 111

fiber-coated, plant-fiber-reinforced clay, borax for fireproofing or stuffed into heated regularly either by the sun or a manufactured by applying clay to burlap treated burlap bags, cotton, flax, or sheep's stove, the thermal mass of the earth will fabric (jute net). For strength, two or more wool. Cellulose insulation made out of re• retain heat in the winter and coolness in layers of reed mats are inserted crosswise, cycled paper ground up and treated with a the summer. with alternating layers of clay paste. Fi• flame retardant can be blown into cavities For earthbag domes built in cold cli• nally, the surface of the board is covered in between rafters with a specially rented mates, if desired the insulation can be in• burlap and transported to a drying station. machine to insulate the ceiling or roof, and corporated in the floor, ceiling, and final Tests with this kind of board have shown in timber frame construction, between layers of the internal and external plaster, excellent results with regard to fireproof, studs in the walls (it is also available in batt which can be significantly thickened to soundproof, deformation, and diffusion form). Hemp cellulose (fireproofed with provide a more insulative finish using a values. Such boards could be used, for ex• mineral salts and called Canobite) can also layer of straw-clay on the inside and paper• Warning ample, as a permanent form combined be purchased, either loosely packed in bags crete outside. Many conven• with straw-clay or blown-in cellulose in• or to be blown in. Wood-fiber boards can tional insulation sulation, or as ceiling panels (see Con• also be used for thermal and acoustic insu• Straw-Light Clay materials create An earthship (rammed struction Resources in the resources list). lation (Tibbies 1997-98). As mentioned above, straw can be coated environmental To prepare straw-light clay, pour the earth in tires) wrapped To increase insulation value in an problems as a They can be screwed, nailed, and sawed, with clay slip called straw-light clay and clay slip on top of a pile of straw, tossing it by straw bale insulation. earthen mix, straw, wood fibers, cork, and result of their then plastered over as a finish. When a used as insulation in many different ways: like a salad with pitchforks. Coat every other air-trapping fibers can be used, ei• energy-intensive smooth surface such as wood framing has stuffed between rafters as roof or ceiling single piece of straw completely with clay ther added into the earthen mix or at• and destructive to be plastered, burlap can be placed over a insulation, placed in the floor using the slip. To test if it is coated enough, take a tached in panels along the walls. Pumice, extraction and wet coat of base plaster and allowed to dry rammed straw technique, or made into bundle of the mix and squeeze it—if it manufacturing perlite, and other minerals used for floors before a final coat, or reed mats can be lightweight blocks to construct relatively sticks together, it is ready. If time allows, it processes. These and screeds can also be added as an aggre• used as lathe between sections of clay thin but highly insulative walls. is then best left for a day or two under a materials can also gate to increase the insulating value of in• board. And as noted in chapter 1, interior To make light clay, pure clay is necessary tarp to mature and improve. cause health partitions can be made with wattle and terior plaster and ovens. One of the best for maximum binding strength. The clay problems during Another application for light clay is the daub or with the rammed straw technique insulating materials for corbeled dome has to be mixed with enough water to turn installation or technique of rammed straw, whereby the described below. construction is pumice-filled bags (see the it into a slurry called clay slip or liquid clay even after, mixture described above is used to con• profile of Kelly and Rosanna's house on because of (always adding the clay to the water, never struct walls and partitions. After being INSULATION page 135), but this material occurs natu• particle migra• water to the clay). If the mix is lumpy or coated with clay slip, the straw-light clay is rally in very few parts of the world and is tion and off- Good insulation in a building can signifi• contains stones, it could be passed through lightly rammed between the form boards costly to purchase and transport. gassing.There are cantly reduce the heating cost. Insulation a 1/8-inch screen. The consistency should (shuttering) with a 2 x 4 (or your feet) until Earthbag domes in sunny climates do now natural can be built into the walls, ceiling, roof, be such that when you dip the palm of it is solid and not spongy. The forms can be not require insulation, if the design pro• insulation and in some cooler climates the floor (see your hand in the mix no lines can be seen moved up to the next lift immediately after materials for vides for passive solar heat in the winter, the section on floors, page 115). It is a ma• on your hand. The purer the clay, the completion of each particular section. To almost any and openings are placed in a way that they terial that will trap small pockets of air. thinner it can be diluted due to its greater preserve the insulation properties (that is, situation. do not allow direct sunlight into the house Natural alternatives to industrial fiberglass binding strength, thereby achieving a trapped air in the straw), it is important in the summer. If the dome is lived in and include straw treated with potato starch or lighter straw-clay mix. for the tamping not to be too hard. BUILDING WITH CLAY 113 112

east and west side, for example) and the Hybrid Earthbag and Straw Bale insulation value of straw bales on the cold a pole tied to the Straw bales are among the best value for earthbag wall providing north side. air space (at intervals of natural insulation, but unfortunately they Straw is an annually renewable re• 2 per bale) string that take up a lot of space. They can be used as source, the waste product of a cereal grain ties the straw straw bale tied to bales to the earthbag wall floor or roof insulation on ladder trusses crop, and can be easily grown and har• earthbag wall earthen plaster covering or as insulation for living roofs. Bales can vested. Bales can also be made out of the straw bales also be used in conjunction with earthbag tumbleweed, sudan grass, and ordinary walls either as internal supplementary in• meadow hay, but straw is the best natural earthbag footing for the straw bale wall sulating walls, creating a three-foot-thick insulator due to its hollow stems that trap wall, or as nonstructural infill in combina• the air, and it is not attractive to vermin gravel trench A house where two (east and west) earthbag walls are structural tion with load-bearing walls or piers, cre• since it lacks nutrients. The straw bale and the straw bales are a nonstructural insulating wall on the ating buildings that have the structural technique represents an entirely distinct north side, with glazed frame construction on the south-facing Detail section through an earthbag wall with straw front for passive solar heating. stability and thermal mass of earth (on the construction system, which needs to be bale wall for added insulation. strings to tie the bales are fed through tubes left in the earthbag wall

Three different ways of integrating earthbag and straw bale wall carrizo or other earthbag wall systems. wooden poles sandwiching the walls

Above: Building with rammed earth.

Left: A rammed straw wall. BUILDING WITH CLAY 114 115

understood as a system in itself before it ture can also be used for stoves and ovens can be properly applied in combination by adding less straw and more sand, per- In addition to being used in wall construction, cob can be used to sculpt furniture in a very freeform way—seating, desks, and shelves. Benches can be made of solid with earthbags, adobe, or cob. Straw bale lite, or pumice to the mixture. These cob with a flue from a woodstove coming through and warming them while the structures can be load bearing or non- earthen heaters can be sculpted with stove is used, creating a "cozy" corner through the winter months.

load-bearing. A number of good books are niches, alcoves, and benches to suit the size stone as a earthen plaster or sculpted border available on straw bale construction (see and shape of a house. By embedding a flue cob can also have flagstone between the embedded in the surface and existing wait cob and the the bibliography). in an earthen bench, you can make a warm can be stabilized with linseed existing wall to oil (in rainy climates covered with lime or lime- stabilized earthen plaster protect the seating area. stabilized earth), slightly sloping to shed wall from stone or rubble INTERIOR DETAILING For the interior partitions or even exte• water moisture Several earthbuilding techniques can be rior walls where the earth has insufficient cob well-tamped binding strength to hold nails carrying the earthbag used for sculpting furniture as well as for well-conditioned construction of small structures and weight of fixtures, the installation of hang• gravel and rubble well-tamped houses. Earthbags, rubble, cob, adobe, the ing cabinets and other furnishings re• gravelbags

different straw-clay mixes, and straw bales quires a nailer board that can be installed Exterior cob bench. Exterior earthbag bench. can all be used to construct the main struc• after the wall has dried. In preparation, ture of sculpted furniture, sealed and wooden stakes should be placed between the rows of earthbags before tamping, or smoothed out with an earthen plaster, existing wall then capped with lime, gypsum, or some embedded in the cob or adobe with a led• earthen plaster cob wall to retain the other clay paint finish for durability. ger board attached across two or more well-compacted rubble and gravel or rubble earth, or solid cob stakes, which provide anchors for nailing. The materials used for creating furni• possible flue from oven well-compacted gravel to heat the bench

adobe or cob wall to retain the rubble

Interior heated bench. Exterior cob seating.

Earth-plastered shelving being constructed with straw-clay blocks and carrizo decking. Then a cabinet or other fixture can be at• rently being revived. In spite of the stereo• tached with screws or nails to this ledger type of "dirt floors," earthen floors need board. not be dusty, fragile, or difficult to clean. The right application of oil and wax makes EARTHEN FLOORS earthen floors waterproof and almost as For centuries, earthen floors were used all durable as concrete. Some of the earthen over the world. Until recently, they were floors I have seen have been walked on the standard floors throughout the south• with high heels, and can take the pressure western United States, where they are cur• of furniture. There is no one correct way of BUILDING WITH CLAY 116 117

constructing these floors. The materials troductory earthen floor booklet (see the 1. Base: This layer should be either undis• used vary according to availability, but the bibliography); therefore, I will only give an turbed soil, or at least a very well-com• quality of the floor primarily depends on outline of the construction method. pacted surface, since it needs to be free of the workmanship. It is possible to create The floor should be poured during the all organic matter and unlikely to heave in Floor, showing earthen floors that are durable and require driest part of the year. It can take between frost, so that no movement occurs. alternative insulation layer of bottles ten days and six weeks to thoroughly dry little maintenance, if certain basic prin• embedded in sand. ciples are understood. The method I out. The layers of an earthen floor are as 2. Waterproofing: This layer is only neces• learned from Bill and Athena Steen of the follows (make sure each layer is fairly level sary in very damp areas that cannot be Canelo Project, who have produced an in• to minimize your work on the final layer): properly drained. The waterproofing can be natural clay such as bentonite (which should be tested prior to construction) or 6. Finished floor: The top structural layer, a synthetic damp-proof membrane. approximately 1 inch (25 millimeters) of Layers of an Earthen Floor trowelled clay-earth mix. The clay-earth 3. Drainage: To stop any moisture from mix should be comparable to a good rising, this is a layer of 6 to 12 inches (150 to earthen plaster mix (see chapter 6), and 300 millimeters) of washed gravel or should be troweled in two half layers; the course sand, tamped down well. If no top layer will need stabilizer. Other options waterproofing membrane is used, the include 4 to 6 inches (100 to 150 millime• gravel needs to be quite large—¾ to 1½ ters) of well-tamped clay-sand-soil mix or inches (20 to 40 millimeters) in diam• 2 to 3 inches (50 to 75 millimeters) of clay- eter—to prevent the rise of moisture. soil mix with psyllium (the mucilaginous powdered seed of the Plantago psyllium 4. Insulation: This layer should be 4 to 6 plant, also used as a laxative). For natural inches (100 to 150 millimeters) of straw- stabilizers, hardening agents such as lime, light clay or pumice, perlite-clay, or bottles blood, or wheat paste can be added (see the embedded in sand, well tamped. discussion of stabilizers in chapter 6).

5. Subfloor: The aim of this layer is to 7. Sealant: Apply several layers of an oil- achieve maximum compaction on top of solvent solution for added protection. Use the insulation, in preparation for the fin• boiled linseed oil or other stand oil, as ishing layers of earth. It should be com• these are oils that dry well, and which can pacted silty or sandy soil, the same as the also be used for other earthen finishes. For base. This is the layer that can take radiant- the solvent, the least expensive is turpen• floor tubing. If a floor heating system is tine, but you may use anything from com• used, the subfloor must be considerably mon mineral spirits to more-expensive

Earthen floor layers with flagstone embedded into the top layer. thicker to provide adequate thermal mass. odorless turpentine or pure citrus oils. BUILDING WITH CLAY 118 119

finished floor layers screeds. Pour the mix between them, and can also be set with adobe mortar for ar• "evening out" layer of lay a straight board across the top of them. eas of the house that get wet frequently, clay with sand and Beeswax for Floors low-density of straw Remove the board farthest from you, and such as the kitchen, bathroom, mud willow, hazel, or In a double-boiler with water in the fill in the void where the board had been room, or entrance hall. carrizo arches bottom section, melt 24 percent beeswax

with more mixture. Reposition the first and 6 percent carnauba wax at 140 to 158 Sealants, Maintenance, and Repair board, level it, and keep going. It is best if degrees Fahrenheit (60 to 70 degrees The top layer should be completely dry your mixture is not too wet and keeps its Celsius). before applying the sealant. To be most ef• shape when each board is removed. For the Add 30 percent balsam turpentine from finished floor layers fective, the oil-solvent solution should be "evening out" layer final layer, hammer in nails so their heads spruce or larch and 40 percent boiled heated, taking care not to reach the point reed or straw-clay are level with the height of the finished linseed oil. rolls where it begins to smoke. Warming en• Increase linseed oil and reduce beeswax floor joist floor. Use them for leveling the board, and pull them out as you go along. courages deeper penetration of the oil to make a softer mix. You may use citrus oil into the floor. If the ambient temperature instead of pine turpentine.

finished floor layers of the room with the floor is warm, the sealant will be better absorbed. Apply "evening out" layer layers of carrizo with a brush, and remove the excess. Each floor joist coat should be applied only thick enough coat 1—apply full-strength oil that it does not begin to puddle, for if al• coat 2—dilute the oil with 25% lowed to puddle it may form a skin on the solvent surface, which will be prone to cracking. coat 3—dilute with 50% solvent Note that both oils and solvents are very Examples of an upper coat 4—dilute with 75% solvent flammable and should be treated with floor with an earthen If you wish to consider construction of floor finish. Screeding. caution when heating. Any brushes or an earthen floor for an upper story, a Each coat should be applied only after rags used during application should be straw-clay mixture can be used to fill in the the previous one is dry. The floor should stored carefully in closed containers to space between the ceiling joists, as shown Here are some other ideas for natural only need four coats to be sealed. For addi• prevent spontaneous combustion. above. Then the layers of earth can be floors. Lay a gridwork of equal-sized 2 x 4 tional sheen and durability, another coat poured upon that base as described below. timbers before pouring the final layers, It is better to apply the oil in a stronger can be applied periodically. The frequency then fill the spaces between them one by concentration in the initial coats, gradu• of maintenance will depend on the wear Construction one, leveling at the same time. The timbers ally reducing the proportion of oil to sol• the floor receives, but for an average floor Use screed boards as wide as the depth of can be permanent or else removable when vents in the following coats. The earthen 6- to 12-month intervals is sufficient. If the layered floor, initially placing them flat the mixture is "leather-hard," and the floor is less porous with each subsequent sheen is not important, the floor does not near the wall where you will start pouring. voids can then be grouted with a different- coat of sealant, but will accept full- have to be recoated for many years. Remember to start at the farthest corner, colored mix. An alternative to a poured strength oil at the beginning. If you want the floor to be not just water working your way out toward the door. adobe floor could be sundried adobe According to the Steens' Earthen Floors resistant but waterproof, after the floor has With an accurate level, keep checking that bricks set in place like tiles with a mud- booklet, the sealant coats can be diluted as dried from the last application of oil, apply each board is level as you use them as sand mortar. Fired brick, tile, or flagstones follows: a coat of wax. Make a paste by melting 1 120 BUILDING WITH CLAY 121

part beeswax with 2 parts boiled linseed bag walls, they should be encased in a cover the wires with a thin strip of metal or either set into grooves between courses or oil. While the paste is still warm, rub it into larger-diameter sleeve that is sloped down plastic to keep the stucco from contacting exposed on the wall surface for future ac• the floor with a clean rag. The wax layer to the outside. That way if the inner pipe the wires. Wiring that is plastered into a cessibility and convenient servicing. The will rub off over time, so reapply it every gets a leak, the outer sleeve will direct the wall is difficult to modify, so test your wir• other option is to consolidate all the wir• few months or once a year. water outside the house where it can be ing fully before plastering; or route your ing on the interior partitions (if they ex• If cracks or other wear-and-tear begin seen, instead of soaking the inside of the wiring in conduit, which can be made out ist), in the ceiling, or in raised floors with to show on the floor surface, it is good to wall without anyone knowing. of plastic tubing or discarded garden hose, floor outlets. patch these places fairly quickly to avoid Electrical wiring and J boxes can be them growing larger in size. When con• placed as the rows of the earthbags go up, structing the floor, save some of the mix or can be added in the grooves between for later repairs, as it will be almost impos• courses before plastering. Cut 12-inch- sible to match the color later. After clear• long (130 centimeter) pointed stakes out ing the area that needs repair and crackup of 2 x 4s to anchor the electrical boxes in off all loose material, add some water to the earthbag walls. After making a notch the dry mixture and mix thoroughly. Then for the box to recess into the earthbag sur• wet the damaged area, fill it in with the face, drive the stake in. Even easier, place mix, and reseal the surface as described the stake in the wall between courses dur• above, with four layers of sealant. ing the laying of the bags. You can screw the box to the end of the stake and place ELECTRICITY AND PLUMBING the wires between the courses of bag. Use For electrical and plumbing utilities, it is heavy-gauge, U-shaped wire pins to hold safest to place all the service ducts that en• the wiring in the grooves. If you are using ter and leave the house below ground level cement plaster internally, you may want to going through the foundations, to prevent freezing and to minimize damage if a pipe does fracture. This can be planned into the design ahead of time, enabling the inser• tion of plastic sleeves through the founda• tion and floor where necessary during construction. A plumbing chase can also be created in partition walls and under the floor. Non- pressurized drainpipes are safe to route through earthbag walls and can go directly out to a separate graywater system for each Electrical box fixed to wooden stake for anchoring in sink. If pipes must be run through earth- earthbag wall. 8

THE EARTHBAG ADVENTURE

ince the inception of this book, numerous earthbag projects have been built. This chapter offers a survey of the earliest Sand therefore some of the most adventurous. These include examples of the Hart's very experimental freestyle dwelling; the amazing demonstration of courage by Shirley Tassencourt, then in her late sixties; and Kaki Hunter and Doni Kiffmeyer's advance• ment of the earthbag technique to true perfection. Each of these projects yields tremendous inspiration and many lessons.

SHIRLEY TASSENCOURT'S DOMES, ARIZONA To my knowledge, the first earthbag domes to be actually inhab• ited were built by Shirley Tassencourt with help from friends and relatives, including her grandson Dominic Howes. Shirley chose the earthbag technology because of its "magic" and her limited finances. As she is an artist who often sculpts with clay, earth seemed like a familiar medium. Between 1995 and 1997, Shirley built three earthbag structures: first, a meditation dome, "Domosophia"; next, a main house dome; then, a rectangular-shaped library with a conventional roof. The soil used to fill the bags was brought from nearby.

The Meditation Dome The meditation dome has an external diameter of 15 feet (4.5 meters)with 1½-foot-wide (45 centimeter) walls sitting on bed• rock, a cement-stabilized row of earthbags below the rafters of the mezzanine level, and a reinforced concrete bond beam pinned to the wall, serving as the compression ring for the opening. Exte• rior and interior plasters are cement stucco. The upper level was

123 THE EARTHBAG ADVENTURE 124 125

Section of the Meditation dome

Above: The first lived-in designed to contain a small studio space desert. Then as I sat in the dome at Cal- son Dominic Howes, and a fun young married couple, Luther and Above: The skylight being constructed on top of the earthbag dome built in compression ring. with a 360-degree view of the surrounding Earth listening to Nader Khalili, I was ob• Cindy McCurtis. We figured it out as we went along. With four of Arizona by Shirley us working for five hours a day in the desert heat using small bags, Tassencourt with her land. sessed with wanting to be in such a cen• Above left: The cost of materials for the main dome grandson Dominic Here's how Shirley tells the story: "At the tered, dynamic, revolving space. Being old in three months we finished the essential dome, Domosophia. A structure and finishes (without utilities) was about Howes. age of fifty-two, as a first-time contractor/ enough (sixty-nine) not to be hampered carpentry crew made the 7-foot-diameter clerestory (with its 360- $6,000, primarily for cement and specially made windows, doors, and skylight. owner-builder of a 1,500-square-foot salt- by reality, I went home and started the next degree view); they brought the spidery structure out in a truck and box on Martha's Vineyard, I thought I had day on the Meditation Dome. Some ad• plopped it on top. We covered it with chicken wire, tarpaper, and Insert: The library was built under a pole supported just made it under the doddering line. But venture, oh my! Lady luck hovered over the stucco, and voila-—I had my heart's desire." roof, which provided a cover for shade. Earthbags were used as infill, as in a post-and-beam as a retired art teacher and potter/sculptor, total project—undertaken by me in my construction. I had another go at it in Arizona's high late sixties, my nineteen-year-old grand• THE EARTHBAG ADVENTURE 126 127

The Main House Dome ALLEGRA AHLQUIST'S HOUSE, The second-story floor rests on a concrete bond beam, and the ARIZONA mezzanine level has a sky view. No other foundation was needed, This house is situated on the land shared as the ground is bedrock. The earth was dug out 6 inches (150 mil• with Shirley Tassencourt in Arizona. It was limeters), and a poured concrete slab finished with tiles. External built by Dominic Howes, finished in 1997. and internal plasters are cement stucco without lath; the uneven It is an example of mixing alternative tech• surface of bags provides enough reinforcement and key-in points. nology with conventional construction. Again, here is Shirley's own account: "Emboldened by our suc• Buttressed earthbag walls stand on a con• cess, in 1995 in a hot September desert, we started on the second, crete foundation, and are tied together larger dome, this time built with an engineer's approval. It took us with a bond beam supporting a timber- five months and 5,000 small sand bags. This dome has a 25-foot trussed roof. Allegra is very content with footprint, with a double (42-inch-thick) earthbag wall 9 feet up to her 625-square-foot house. The house the base of the mezzanine level with earth rammed in the cavity, took four months to build and cost 40,000 which is sealed with a concrete bond beam. The outer wall acts as dollars, the biggest expenses being a con• a huge buttress, and could have been considerably smaller, but ventional roof, foam insulation, concrete there was little precedent for this kind of construction using small foundation, windows, doors, cement

Section and plan of Shirley Tassencourt's Main House bags. We hand-lifted 25,000 pounds of earth on straw-bale scaf• stucco, and labor, which was about one- Above: Allegra's square dome. Note the double earthbag wall up to the folding for our 20-foot-high building, crowned with a 5-foot-high, quarter of the final cost. The floor is brick house. mezzanine level. 7-foot-diameter plexiglass skylight. Skylights offer gifts of sky and on sand with floor-heating tubing in the Left: Sketch plan of the landscape unusual to dome construction. Twelve-inch PVC tubes sand layer. The south-facing windows pro• house. through the second-floor walls plus a window-door to the balcony vide passive solar heating; in fact, the in- allow inexpensive fenestration and continuous air flow from two floor heating system (regulated by a ther• doors below, which are open all summer. [Author's note: In Ari• mostat) has only been used six times in the zona, this skylight has to be covered in the summer due to the in• past three years in spite of cold winters. tensity of the sun, and in winter it causes considerable heat loss. The skylight should be off-center, angled south.] timber truss "My grandson was an apprentice for the first dome, foreman on timber wall plate for the truss to sit on

the second dome, and a contractor on our neighbor Allegra's concrete bond beam with contin• uous reinforcement, pinned to the house (see page 127). Dominic went on to build a large, rectangular earthbags at intervals earthbag- and roof-truss hybrid structure in Wisconsin. Here in earthbag wall with two strands of Arizona, I and two other elder women have thirty acres off-the- 4-point barbed wire between courses grid. We embrace Permaculture, gardening till the grasshopper 2" (50 mm) of styrofoam insulation plague arrives in July. We do ceremonies, and connect deeply with chicken wire to enable the external plaster to stick the land through our fifteen-acre natural medicine wheel (made concrete footing with big boulders marking the cardinal directions on a circle). We

want to encourage others.... If we can do this, anyone can!" Section showing wall-to-roof junction. 128 THE EARTHBAG ADVENTURE 129

HOUSE BUILT BY DOMINIC HOWES, WISCONSIN

Above:The finished The house is situated in an extreme cli• therefore, the treatment of the earthbag Structural section through the south wall. Detail section through the south wall. house. mate where the temperatures range from wall is carried out in a similar manner. It is as low as -40 degrees Fahrenheit in the almost entirely a conventional house with

winter up to the high 80s in the summer, standard timber-frame construction and The house under with heavy rainfall through the summer artificial foam insulation, but instead of construction. months. Designed by the client, it has two using brick or concrete for the structural stories where the second is of conventional walls it uses the earthbags filled with the construction, with high windows for pas• local earth. sive solar access. The earthbag part of the house took This house was built by Dominic three weeks to build. The floor area of the Howes almost directly after construction house including the first floor is approxi• of Allegra Ahlquist's house (page 127); mately 1,500 square feet. 130 THE EARTHBAG ADVENTURE 131

Sue Vaughan in front of her scoria-filled earthbag dome, which is covered with standard cement stucco.

Above:The upper section of the dome from the inside, showing the geodesic structure.

SUE VAUGHAN'S HOUSE, COLORADO CAROL ESCOTT AND STEVE KEMBLE'S HOUSE, THE BAHAMAS Sue Vaughan wanted a very small, round house, so Here is a house designed and built in the Bahamas by Carol Escott and Steve Kemble of The finished house. with the advice of Kelly Hart, she and two helpers Sustainable Systems Support. The first phase of the construction, which consisted of the built this 14-foot (4.2 meters) diameter, shallow structural earthbag walls, was constructed with the expert help of Kaki Hunter and Doni Preparing the foundation. dome with a sleeping loft made of scoria-filled Kiffmeyer, who have developed site-built hand tools and a process for building that sim• bags. A concrete bond beam at the height of the plified and "neatened" this very labor-intensive construction method. Kaki and Doni's door lintel supports a geodesic structure form• Honey House is described on page 140. ing the upper part of the dome. This is a hybrid design where the first story is constructed out of bags filled with native soil, upon which sits a second floor and roof constructed out of conventional timber frame. The second-floor joists are fixed to a reinforced concrete bond beam on top of the earthbag wall. The house was built on a small island very close to the beach. The fill for the earthbags was locally available sand dredged from the sea, which was very fine and contained a high Section of Sue Vaughan's dome. proportion of crushed coral, so it was very easy to compact. When slightly moistened and tamped, the bags turned to solid blocks. 132 133

Since the ground around the house was ent. The most abundant and easily gath• to encourage biodiversity and habitat for sand, drainage was not a problem; there• ered natural building resource is sand. beneficial wildlife, as well as for privacy fore, the foundation was very shallow with Carol and Steve realized that where dredg• around the house. no gravel trench below, simply one row of ing had occurred for a marina there were To collect the breezes, Steve designed sand-filled bags below ground level. piles of sand mixed with crushed coral, the home to be two stories with an at• In an article in Earth Quarterly (see the available free for the taking. When slightly tached deck on the second level. The roof bibliography), Carol and Steve describe dampened and well tamped, the lime in is hipped to shed heavy hurricane winds. the premise of their design process: "Faced the coral acts as a natural binder with the The first level has walls made of sand- and with the challenge of building on a remote sand, which sets into a hard block. crushed-coral-filled polypropylene bags island in the Bahamas, we realized that... Since the climate is subtropical, hot and along the perimeter, with a peaked, 8- current construction trends in this part of humid, ocean breezes are needed for com• point-arch opening in each of the six sides. the world rely on the importation of al• fort. Most people clear-cut the bush to al• These arch openings have been left open most all building materials in even the re• low the breeze to blow through and to for breezes, and the covered lower level is motest of locations. In keeping with our eliminate hiding places for the mosqui• used for utility, storage, and a workshop. work in the States, we wanted... to use this toes, but Carol and Steve let the foliage At the center of the lower level is a 3,000- project as a demonstration of appropriate grow around their site in order to provide gallon, concrete-block rainwater cistern, earth building techniques ... in hope of overstory protection for new plantings, which also serves as a load-bearing sup• influencing a shift in... building/develop• shade to help with moisture retention, and port for the second level. ment needs." These earthbag walls used misprinted First floor under construction. line of roof overhang Carol and Steve faced serious difficul• 50-pound rice sacks for the first four feet, ties: The Bahamas are subject to devastat• wall plate anchor bolted to bond beam resulting in a 20-inch-wide (50-centime• ing hurricanes each summer and fall. ter) wall. The next four feet were built with reinforced concrete bond beam There are voracious termites, making any continuous tubing, resulting in a 14-inch- wood product is subject to attack. It also reinforcement rod pins wide (35 centimeter) wall. Since the earth- rains frequently and things may stay moist bag walls were made very smooth with a four-point barbed wire for weeks. The intense summer sun can high-precision finish, there was no rough cause even pressure-treated wood, if ex• straps over the bond beam texture to permit the stucco to be effec• reinforcement rods posed, to deteriorate in as little time as five tively keyed into the wall surface, which to years. well-compacted bags filled with reinforce the cement render was therefore local sand According to Carol and Steve, the Baha• covered with a layer of chicken wire, se• mas have developed very little industry cured to the walls with galvanized tie- except for tourism, so most building ma• wires laid between bag courses as the walls terials are imported from the United were built. The bond beam was strapped

States. In terms of native resources, the compacted sand to the earthbag wall using both the chicken majority of vegetation is low bushes, with wire and the poly strapping, which was trees for lumber being virtually nonexist• Plan of ground floor. ratchet tightened before stuccoing. Plan of ground floor, used as utility area and workshop. 134 THE EARTHBAG ADVENTURE 135

The 512 square feet (40 square meters) of the ground floor, earthbag stage of the house took three months to build, requir• ing 500 bags and a 1,400-foot roll of polypropylene tubing. Carol and Steve conclude: "After the completion of Phase 1 (the earthbag wall base) we were very pleased with the results of the project. The islanders have accepted it, stating that it looks like the old 'rubble stone' ruins around the island. It feels very sturdy... enough to take the worst hurri• cane, relentless sun, and regular wind• blown rains. It cost a fraction of the money any other option would have, to get to this point. Although it took a lot of manual la• bor, it is a doable method with only mini• mal hand tools, and we had fun coordinat• ing our team work into a smooth process. The three young men we trained are look• ing at building houses for themselves us• KELLY AND ROSANA HART'S HOUSE, COLORADO ing this method, and are even discussing This house, designed and built by Kelly wall covered with papercrete inside and becoming contractors for other people." and Rosanna Hart of Hartworks, Inc., is in out will have an R-value as high as 40, a small town at 8,000 feet in the foothills of which is higher than building codes re•

Top: Ground floor during construction. the Sangre de Cristo Mountains of south• quire. Scoria is also light and fast to work ern Colorado. Several interesting features with. Bottom: Earthbag stairs. distinguish the main dome of this house. Another unusual aspect of this house is The walls are constructed of bags that that although the main structural form contain scoria, a very porous, pumicelike appears to be a dome, it is not a self-sup• volcanic stone. It is locally available, and porting corbeled dome. For a true cor• like pumice, it has many air pockets and so beled dome, the design needs to be circular is very light. Due to its porosity, scoria is a in order to create an evenly curved wall good insulator and also provides thermal upon which the vertical and horizontal Roof structure to support the scoria- mass, so the house can absorb the sun's forces are equal everywhere. In this case, filled bags. heat and retain it throughout the night. the plan is oval, so timber poles have been Kelly estimates that the finished scoria bag used as a type of pitched-roof teepee ar- 136 THE EARTHBAG ADVENTURE 137

rangement, insulated with scoria-filled below ground level. Then 6 to 8 inches of (500 millimeters) wide, making sure the sand is damp when filling bags partially supported by the poles. loose scoria was put over the entire build• the bags, well tamped and buttressed.] So we switched to scoria, This dome is also covered with a differ• ing area to serve as insulation and good which is a much lighter material and will pack into a tight, stable ent type of plaster, which is water resistant drainage. There is no other foundation or wall. Because of the lightness of the scoria, in addition to the usual and insulative: a mixture of paper and ce• drainage, since the soil is pure, fine sand. four-point barbed wire running between each course of bags, we ment or lime, or a combination of the two, We tried using the on-site dry sand to fill tied the bags to each other with poly baling twine [see photo on often called "papercrete" or fibrous cement. our polypropylene bags (misprinted rice page 54], which provides a matrix of fabric across the entire wall to The house is a hybrid, a juxtaposition of bags), but soon discovered that at a certain resist fragmenting. It also gives the finish plaster something to different materials, as well as a network of point after about five feet of stacking, the grab on to (especially important on interior walls, where in domes interconnecting structures allowing the bags would not hold their shape and with• you are working against gravity). area of the house to be quite large without out buttressing the wall would collapse. "We used individual bags as building blocks, rather than using using one single dome. [Author's note: When building with very long tubes of material, because the small bags are easy for one per• Kelly Hart describes part of the con• sandy soils, which consist of round par• son to carry, and when we tried putting the scoria in long tubes, struction process: "The sloping site was ticles of sand, a test structure should be leveled and dug down about a foot below built prior to construction of the main the eventual floor level, which was 5 feet house, with bags not less than 20 inches With an old woodstove in the foreground, the dining area under the loft can be seen beyond. Flagstones are set in adobe in the foyer. Beyond the table is a windowseat constructed with earthbags.

Plan of ground floor. 138 THE EARTHBAG ADVENTURE 139

there was a tendency for the whole thing to roll off the wall. [Author's note: This was due to the fact that the tube was narrow and scoria cannot be made compact in the same way that slightly damp earth or sand can. Therefore it may be advisable not to fill the tube completely but loosely, to allow for tamping. Also, always carry the fill to the bag, eliminating the need to lift.] With the in• dividual bags, the bottom seam provides a distinct flat orientation that resists rolling. "Bags were stacked over a wooden form for the arched door• ways. We used a plastic pipe to make air vents. Many of the win•

Kelly applying dows were created using old wagon wheels or culvert couplers to papercrete to the hold the circular shape, and since most of the windows are not outside of the dome. operable, the glass used was often unclaimed or cut to the wrong This doorway has a span of 6 feet made size; these thermal panes can be found cheaply at glass shops. They possible using the were imbedded directly in the papercrete (which is so dimension- double-bag, cross- ally stable it will not break the glass), and a second, final coat of hatch method of scoria arch. papercrete with sand was applied to the outside, overlapping the glass. "The space connecting the two domes is framed with wood on the south side, while the north side is an insulating scoria-bag wall in the shape of a semicircle. Because of the expanse of glass in this greenhouse section, and the need for a flat place to mount the solar Kelly explains, "With the pantry dome open, you can water panels and PV modules, I chose to use conventional wood see how the bags are stacked, those long rafters framing on the south. The north side of the house is bermed with helping to support the bags. Because of the about four feet of earth, and a mound of earth covers the pantry in relatively shallow pitch, bermed with earth on the Unbuttressed arch.To create an arch spanning more outside, and the considerable weight it would bear, I the north. than 3 feet using lightweight scoria bags, Kelly decided to use logs. Before the pantry was backfilled "The final layer on top of the papercrete is lime-silica, sand, and devised the crosshatched, double-bag arch system with sand, I put on two layers of 6-mil plastic shown here. white Portland cement plaster. sheeting. The dome has not leaked and stays around 40 to 50 degrees Fahrenheit." "Because of the elliptical shape, this dome is not as inherently stable as it would be if it were circular, which is why I used the timber pole. The forces are not uniform, so I had to struggle to keep the shape I wanted. I would not recommend that anyone re• peat this experiment, though I do love the shape and feeling as it has turned out." Kelly has made a video of this construction process (see the re• sources list). 140 THE EARTHBAG ADVENTURE 141

bags per person per hour, so a team of four then backfilled with gravel and earth. The averaged sixteen bags per hour, and about interior walls are earth plastered with local ninety-six bags in a 6-hour day. The white clay and milk-based alis paint. The Honey House is made of eight hundred earthen floor is poured adobe over 4 bags overall. The whole structure took just inches (100 millimeters) of gravel and nineteen days to complete. stone with mud mortar, sealed with a The earthen plaster was made with 7 natural, oil-based floor finish. tons of cob, which took seven days to apply Except for utilities, windows, and all the way up to the roof, which has a 6- doors, the cost of this house was $1,020, inch base for a "live cob thatch roof," where which was the cost of the bags (a quarter of living grass roots were mixed into the final the final cost, including delivery), home• layer of roof plaster. made tools, plywood arch forms (which are reusable), chicken wire, backhoe rental, twenty bales of straw for the earthen plaster, two rolls of barbed wire, and the 40 tons of sand, delivered. In their manual Earthbag Construction (see the bibliography), Kaki and Doni have described their method this way, "We have adopted the FQSS stamp approval—Fun, Quick, Simple, and Solid. By following this The Honey House with criterion, we have made the ease of the con• sculpted gutters and KAKI HUNTER AND DONI KIFFMEYER'S HONEY HOUSE, UTAH grass seeded in the struction process our priority. As long as the First floor under construction. final layer of earthen work is Fun and Simple, it goes Quickly plaster. This house was designed and built in down buttresses, and away from the foun• and the results are Solid. When the work Moab, Utah, by Kaki Hunter and Doni dation. The interior has a sunken floor, 2 feet becomes in any way awkward, FQSS de• Kiffmeyer of the pioneering firm OK OK No cement was used in this structure! (60 centimeters) deep. The earthbag wall teriorates into Frustrating, Quarrelsome, OK Productions, who have elevated earth- The bags used were small "misprint" starts at this level; there is no concrete Slow, and Stupid, prompting us to stop, bag construction to a precision craft. The bags of two sizes: 17 inches wide by 30 foundation. Plastic bags were wrapped change tactics, or blow the whole thing off structure is a corbeled earthbag dome with inches long and 22 inches wide by 36 around the exterior of bags below grade and have lunch (returning refreshed often a -foot meter) interior diameter. 12 (3.6 inches long. The fill material used was "re• for waterproofing from ground moisture, spontaneously restores FQSS approval)." Forty tons of earth were needed to fill the ject" sand from a local gravel yard. This bags, and 9 more tons were used for had the ideal ratio of 25 percent clay to 75 sculpted adobe and for a "living thatch" percent sand for rammed earth construc• roof. The gutter system is sculpted adobe, tion. The time taken for filling and tamp• which steers the water around windows, ing the bags averaged four of the smaller THE EARTHBAG ADVENTURE 142 143

THE LODGE "NJAYA," MALAWI THE NEW HOUSE OF THE YAQUIS, MEXICO

In structures like the bathing room in the backpackers' lodge "Njaya" in Malawi, in southeast The indigenous Yaqui community of the village, and no sanitation facilities Africa, Adrian Bunting experimented with the sandbag technology prior to constructing Pueblo de Sarmiento is located on the out• apart from an outhouse. In spite of the low a larger sandbag project—an eco-lodge in southern Tanzania. As Adrian explains, "I was skirts of the city of Hermosillo, capital of standard of living, we remarked upon a trying to get the hang of the sandbag technology based on a couple of photos on the Web. the Mexican state of Sonora, which bor• sense of cheerfulness all around. The beach in Tanzania is as remote as you can probably get, so the plan was to build as ders the United States. Mexico's govern• Taking stock of the materials available much as possible with the available materials, basically sand and coconut trees. In Africa, ment gave a ten-acre parcel of undevel• on-site, we saw that one of the concrete is what everybody wants to build with, but a lot of this is done with lime obtained oped land to the Yaquis of Hermosillo in few resources that was abun• from live coral reefs, sustaining huge damage. It's also very expensive. I was sent to Malawi to 1995. This land is a desert at the bottom of dant was earth—very sandy see if the sandbag technology was a viable option for constructing chalets in Tanzania. As the surrounding hills. with hardly any clay—so the far as I could see, it was worth trying if only to achieve the thermal insulation these build• Giovani Panza, of the organization earthbag technology would be ings provide, and also the ease of sealing against mosquitoes, since any timber building is Itom Yoemia Vetchivo, whose mission is to very appropriate. impossible to make bug-free." find funding for projects that improve the The house was to be a Nader The construction procedure used in Malawi is very different from the method de• Yaqui community's living conditions, be• Khalili-designed, low-cost pro• scribed in this book. As Adrian explains, "The bags are filled with pure dry lake sand, of a came acquainted with Pueblo de Sarmi• totype, the "three-vault house," granite type. There is no barbed wire, and I did find the bags slipped during construction ento through a conference of indigenous which utilizes a simple design so the roof has reinforcement bars bent and used as a permanent form. The corridor is just peoples of the Mexico-U.S. border, which based on the repetition of single stacked in an arch. was held in Hermosillo. In the spring of arched units, simplifying con• "You might be interested in a conversation I had with the builder when we started the 1997, Itom Yoemia Vetchivo received a struction. Khalili's arrangement roof. He was shaking his head, so I asked him why. He replied that this wasn't a roof. I asked grant of four thousand dollars to build the of vaults eliminates the need for him why, and he replied, 'A roof is made of tin.' I Yaqui community a prototype low-cost corridors, and additional vaults said, but tin is noisy when it rains, it shelter, and they approached Cal-Earth can be added later easily. Resi• heats up quickly in the sun, and bent reinforcement rods (rebar) for help. With two volunteers experienced dents have a view through the forming a dome shape when it's old mosquitoes get in conventional construction who were depth of two vaults at one time, in. 'It is still a roof,' he re• earthbags stacked flat carrying out apprenticeships at Cal-Earth, increasing the sense of interior without barbed wire plied. But this is ten times I offered to coordinate this project, which spaciousness, and variety can be cheaper, I pointed out. was organized as a three-week volunteer introduced through placement 'I see,' he said...." project. of windows and other elements The people of Pueblo de Sarmiento such as niches and alcoves. A usually build their own homes out of wind catcher faces prevailing summer Top: A house con• structed of corrugated whatever is on hand: cardboard, corru• breezes to direct air into the house for asphalt, which becomes gated asphalt sheeting, and small pieces of cooling. In addition, the vaulted curve of unbearably hot in the the roof creates shaded zones of cooler air, Mexican sun. The permanent, dome- found timber. These structures need to be shaped structure used rebuilt after the seasonal hard rains. They while the sun's path overhead encourages Above: Prototype of the to support the had one source of fresh water coming into air movement inside house by gradually three-vault house. sandbags. 144 THE EARTHBAG ADVENTURE 145

shifting the shaded zone up and over the merriment, they embarked on this adven• vault. ture with space-age technology. Their first Contrary to my intentions, the people day of laying bags was very slow, but soon of Sarmiento were asked to prepare a con• they gained experience and speed. The crete foundation prior to our arrival, Cal-Earth advisers, who were not them• which was the first of many unnecessary selves accustomed to alternative construc• measures in this project. Due to this extra tion, had insisted on putting 12 percent ce• work, time was lost. ment into the earthen fill, thereby treating A team of fifteen Yaqui workers had as• the bags as concrete forms instead of sembled for the project. Some were from rammed earth. In six days, the laying of the this community, and others came from the earthbags was complete and the structure village of Ciudad Obregon, farther south. was ready for the vault construction. Over They were all to receive standard Mexican the whole week, the speed of the bag laying wages, which to us meant that their motive averaged 23 feet per hour per team, with for working hard would not be primarily three people in each team. educational. Yet with all this available la• At this stage, we faced a huge di• is the point of building a house without the roof structure; and rigid foam, for the bor, I could not have foreseen what could lemma—whether to build some kind of any wood if you are going to use vast insulation. There were numerous possible go wrong. timber formwork (the cost of which would amounts of wood for the formwork?" was alternatives. For instance, the foundations Once the concrete of the footings had come to more than what was budgeted for the commonsense question. A way of could have been inexpensive gravel- or cured, the work began. At first, earthbag the whole house), or instead to try and building a vault using reinforcement rods, rubble-filled trenches; or two stabilized construction seemed very strange to the devise a way of constructing the vault us• expanded metal mesh, and rigid foam in• earthbag rows laid directly on undisturbed Yaquis, and reluctantly, but with great ing permanent, built-in formwork. "What sulation was devised. "What happened to ground, since this is not an earthquake the idea of natural, alternative construc• area; or two courses of bags filled with tion?" was my constant question. gravel laid on undisturbed ground (see the Unfortunately, the concept of empow• descriptions of earthbag foundations in erment through use of the simplest tech• chapter 3). niques and the most available materials There was no need to put any cement in was almost lost, because the local people the fill for the walls. The earthbag technol• were unable to build more of these build• ogy has been specifically developed for ings due to the vast cost of the materials building in areas with no clay or wood, and used in the prototype. So what went using unstabilized earth would have been wrong? Why did the project's cost escalate entirely practical at Sarmiento. For the from the four thousand budgeted to ten roof structure, it would have been better to thousand dollars? The most expensive use the locally grown, bamboo-like carrizo material costs of the project were: cement, reed for vaults (see page 67), or corrugated for foundations, walls, and roof; metal, for metal sheeting, which is cheap and easily 146 THE EARTHBAG ADVENTURE 147

available. As for insulation, a straw-clay ways was a success. The Yaqui workers mix would have been preferable to expen• from Hermosillo had never worked so sive rigid foam (see the discussion of roofs closely with Yaquis from other areas, nor in chapter 5). with foreigners. The process was truly a This project underscored the truth that communal experience, marked by con• a thorough understanding of any building tinuous problem-solving and endless technique is necessary to avoid unneces• laughter. Everybody was learning one or sary cost and complexity. Moreover, when two of the languages that were being spo• working with builders who speak different ken at all times. Yaquis were actively in• languages, it is important to acquire the volved in the formulation of the budget basics of the local people's language in or• and the purchase of the materials (Kari der to work effectively. Unless your trans• 1997). Ultimately, the "New House of the lator has extensive knowledge of the build• Yaquis" was truly a surprise to everybody. ing process, it will be difficult to have any It was built by the concentrated labor of in-depth communication. the whole community, and because the ef• Yet in spite of our feeling that we made fort was demanding of everyone, it left a several big mistakes, the project in many deep impression on every person involved.

Top, and top, right: When the reinforcement rods are fixed in their arched shape, the structure is strong and resilient.

Above: Expomat mesh fixed under the reinforcement rods to form a rough surface for the soil-cement coating layered on top.

Right: View from vault 1 of the proposed entrance area and the intersection of vaults 1 and 2. AFTERWORD BIBLIOGRAPHY

Andreson, Frank. "Oh Muddy Clay, O Clayish Loam: Introduction to German Clay Building To live in a natural house is a privilege. Techniques." Joiners Quarterly: The Journal of Timber Framing and Traditional Building 37 (1997): 18-23. Through the process of natural building, we can reconnect with At Home with Mother Earth. Video recording. Los Angeles: Feat of Clay, 1995. the basics. We can find simple solutions to seemingly complex Beale, Kevin. Factsheet on Straw Bale Construction. Machynlleth, Wales: Centre for Alternative problems, often allowing nature instead of machinery to do the Technology, 1997. work. We can create communities that reconnect us with the earth Bedford, Paul, Bruce Induni, Liz Induni, and Larry Keefe. Appropriate Plasters, Renders and Finishes and with each other, for earth itself is the most wonderful mate• for Cob and Random Stone Walls in Devon. Exeter, U.K.: Devon Earth Building Association, 1993. rial, feeding us and housing us. And to possess knowledge of some Bee, Becky. The Cob Builders Handbook: You Can Hand-Sculpt Your Own Home. Cottage Grove, of earth's mysteries is a great gift, allowing enormous freedom. Oreg.: Groundworks Press, 1997. Distributed by Chelsea Green. I hope that all those looking through the pages of this book Billatos, S. B., and N. A. Basaly. Green Technology and Design for the Environment. London: Taylor & draw inspiration to create their own home, and to adapt their Francis, 1997. house to its unique, individual, and distinctive environment. CRATerre, with Hugo Houben and Hubert Guillaud. Earth Construction: A Comprehensive Guide. Villefontaine Cedex, France: Intermediate Technology Centre, 1994. It's your game, it's your joy—go and play! Crews, Carol. The Art of Natural Building: Earth Plasters and Aliz. Kingston, N.M.: Network Productions, 1999. Day, Christopher. "Human Structure and Geometry," Eco-Design Journal 3, no. 3 (1995). . Places of the Soul: Architecture as a Healing Art. Glasgow: Collins, 1990. Denyer, Susan. African Traditional Architecture: A Historical and Geographical Perspective. New York: Africana, 1978. Devon Historic Building Trust. The Cob Buildings of Devon 1: History, Building Methods, and Two of the new owners of the three vault house. Conservation. Exeter, UK: Devon Historic Building Trust, 1992. Droege, Sam. '"How to' book, 1861," archived in 1997 on CREST's Straw-bale Listerv: . Easton, David. The Rammed Earth House. White River Junction, Vt: Chelsea Green, 1996. Escott, Carol, and Steve Kemble. "Earthbag Construction in the Bahamas." Earth Quarterly 2 (1997): 24-27. Farrelly, David. The Book of Bamboo. London: Thames & Hudson, 1996. Fathy, Hassan. Architecture for the Poor: An Experiment in Rural Egypt. Chicago: University of Chicago Press, 1986. Frei, Otto. Tensile Structures. Cambridge: M.I.T. Press, 1969. Hahn, Tom. "Good Shoes: Foundations." The Last Straw 16 (1996):1-15. Hart, Kelly, and Rosana Hart. Video recording. A Sampler of Alternative Homes: Approaching Sustainable Architecture. Crestone, Colo.: Hartworks, 1998.

149 148 150 BIBLIOGRAPHY 151

Hidalgo, Oscar L. Manual de Construccion con Bambu: Construction rural - 1. Bogota: Universidad Rapoport, Amos. House, Form and Culture. Englewood, N.J.: Prentice Hall, 1969. Nacional de Colombia, 1981. [Estudios Techicos Colombianos Ltda., Apartado Aereo Richardson, T. L., and E. Lokensgard. Industrial Plastics: Theory and Application. Albany: Delmar, 50085, Bogota, Colombia.] 1989. Hunter, Kaki and Doni Kiffmeyer. Earthbag Construction. Moab, Utah: OK OK OK, Productions, Rigassi, V. Compressed Earth Blocks, Volume 1: Manual of Production. Eschborn, Germany: GATE, 2000. 1995. Kachadorian, James. The Passive Solar House: Using Solar Design to Heat and Cool Your Home. Rudofsky, Bernard. Architecture without Architects: A Short Introduction to Nonpedigree Architecture. White River Junction, Vt.: Chelsea Green, 1997. Albuquerque: University of New Mexico, 1964. Kanuka-Fuchs, Feinhard, and Jennifer Ratenbury. Biological Natural Organic Paints and Surface Schofield, Jane. Lime in Building: A Practical Guide. Crediton, U.K.: Black Dog Press, 1994. Treatments. Auckland, N.Z.: Building Biology and Ecology Institute of New Zealand, 1991. Smith, Michael G. The Cobber's Companion:-How to Build Your Own Earthen Home. Cottage Grove, Keefe, Larry. The Cob Buildings of Devon 2: Repair and Maintenance. Exeter, U.K.: Devon Historic Oreg.: The Cob Cottage Company, 1998. Building Trust, 1993. Solberg, Gordon. "A Colorado Papercrete Tour." Earth Quarterly 4 (1999): 14-21. Kemble, Steve. How to Build Your Elegant Home with Straw Bales: A Guide for the Owner-Builder. . "Fibrous Cement: A Revolutionary Building Material." Earth Quarterly 1 (1997): 2-15. Bisbee, Arizona.: Sustainable Systems Support, 1995. . "How To Build a Papercrete Mixer." Earth Quarterly! (1998): 12-18. Kennedy, Joseph F. The Art of Natural Building: Design, Construction, Technology — Compiled from Spence, R. J. S., and D. J. Cook. Building Materials in Developing Countries. Chichester and New Presentations at The Natural Building Colloquia Southwest. Kingston, N.M.: Network York: John Wiley and Sons, 1983. Productions, 1999. Steen, Athena, and Bill Steen. The Beauty of Straw Bale Homes. White River Junction, Vt.: Chelsea . "Expanding the Horizons of Earthbuilding: New Research from the California Institute of Green, 2000. Earth Art and Architecture." Adobe Journal 11 (1994): 16-21. . Earthen Floors. Elgin, Ariz.: Canelo Project, 1997. Khalili, Nader. Ceramic Houses and Earth Architecture: How to Build Your Own. London: Harper 8c . "The Straw Bale Earthen House." Adobe Journal 12/13 (1997): 42-45. Row, 1986; Los Angeles: Burning Gate Press, 1990; Hesperia, Calif.: Cal-Earth Press, 1996. Steen, Athena, Bill Steen, and David Bainbridge, with David Eisenberg. The Straw Bale House. . "Lunar Structures Generated and Shielded with On-Site Materials." Journal of Aerospace White River Junction, Vt.: Chelsea Green, 1994. Engineering 2, no. 3 (1989). Stern, Ephraim. Dor: Ruler of The Seas. Jerusalem: Israel Exploration Society, 1994. King, Bruce. Building of Earth and Straw: Structural Design for Rammed Earth and Straw Bale The Straw Bale Solution. Video recording. Santa Cruz, N.M.: Networks Production, 1998. Architecture. Sausalito, Calif.: Ecological Design Press, 1996. Distributed by Chelsea Green. Stulz Roland, and Kiran Mukerji. Appropriate Building Materials: A Catalogue of Potential Solutions. Minke, Gemot. Earth Construction Handbook: The Building Material Earth in Modern Architecture. St. Gallen, Switzerland: SKAT Publications, and London: IT Publications,1993. Southhampton and Boston: WIT Press, 2000. Swan, lames, and Roberta Swan. Dialogues with the Living Earth: New Ideas on the Spirit of Place Mollison, Bill. Permaculture: A Designer's Manual. Tyalgum, Australia: Tagari, 1988. from Designers, Architects, and Innovators. Wheaton, Ill.: Quest Books, 1996. Muller, R. "Hesperia's Domes Pass Seismic Tests." The Daily Press, 30 September 1993. Thomas, Lewis. The Lives of a Cell. New York: Viking Press, 1974. Myhrman, Matts, and S. O. MacDonald. Build it with Bales: A Step-by-Step Guide to Straw-Bale Thompson, Kim., et al. Straw Bale Construction: A Manual for Maritime Regions. Ship Harbour, Construction — Version Two. Tucson: Out on Bale, 1999. Distributed by Chelsea Green. Nova Scotia, Canada: Beautiful Sustainable Buildings, 1995. Nerburn, Ken. Neither Wolf nor Dog: On Forgotten Roads with an Indian Elder. San Rafael, Calif.: Tibbets, Joseph M. The Earthbuilders Encyclopedia. Bosque, N.M.: Southwest Solaradobe School, New World Library, 1994. 1989. Norton, John. Building with Earth: A Handbook — Second Edition. London: Intermediate Technol• Tibbies, R. "Building with Hemp." Building for a Future (1997/98): 16. ogy, 1996. Trimby, Paul. Solar Water Heating: A DIY Guide. Machynlleth, Wales: Centre for Alternative Oliver, Paul. Encyclopedia of Vernacular Architecture of the World. Cambridge: Cambridge Univer• Technology, 1996. sity Press, 1997. Van der Ryn, Sim. The Toilet Papers: Recycling Waste and Conserving Water. Sausalito, Calif.: Outram, Iliona. "The Best of Times for Earth Builders: Research at Cal-Earth." Adobe Journal 12/13 Ecological Design Press, 1994. Distributed by Chelsea Green. (1996): 52-58. Vittore, Phillip. "Dome and Vault Engineering." Adobe Journal 12/13 (1997): 56. . "Interview with Nader Khalili." Adobe Journal 12/13 (1997): 54. Woodward, I. Nature's Little Builders. Thailand: Sirivanata Palace Press / Electric Paper, 1995. Panza, Giovani, et al. U Vemela Hiakim Kari, The New House of the Yaquis. Tucson: Itom Yoemia Zelov, Chris, and Brian Danitz. Ecological Design: Inventing the Future. Video recording. Ecological Vetchio, 1997. Design Project, 1996. Distributed by Chelsea Green. Pearson, David. The Natural House Catalog. New York.: Simon Schuster, 1996. Ziesemann, Gerd, Martin Krampfer, and Heinz Knieriemen. Naturliche Farben: Anstrkhe und Potts, Michael. The New Independent Home: People and Houses that Harvest the Sun, Wind, and Verputze selber herstellen. Aarau, Switzerland: AT Verlag, 1996. Water. White River Junction, Vt.: Chelsea Green, 1999. RESOURCES

PERIODICALS

Adobe Builder. Southwest Solaradobe School, PO Box 153, Bosque NM 87006 USA. Telephone: +(505) 861-1255. Internet: www.adobebuilder.com . Adobe Journal. Published by Michael Moquin, PO Box 7725, Albuquerque NM. 87194 USA. Telephone: +(505) 243-7801. Building for a Future. The Association for Environment-Conscious Builders. Nant-y Garreg, Saron, Llandysul, Carmarthenshire, SA 44 5EJ England. Telephone: +01559 370908. Building with Nature. PO Box 4417, Santa Rosa CA 95402. USA. Telephone: +(707) 579-2201. Designer/Builder. 2405 Maclovia Lane, Santa Fe NM 87505 USA. Telephone: +(505) 471-4549. Earth Quarterly. Box. 23, Radium Springs NM 88054 USA. Telephone: +(505) 526-1853. Eco Building Times. Northwest Eco Building Guild, 217 Ninth Ave., North Seattle WA 98109 USA. Eco Design. PO Box 3981, Main Post Office, Vancouver BC V6B 3Z4 Canada. Environmental Building News. 122 Birge Street, Suite 30, Brattleboro VT 05301 USA. Telephone: +(802) 257-7300, internet: www.ebuild.com . Erosion Control: The Journal for Erosion and Sediment Control Professionals. Published monthly by Forester Communications, Inc., 5638 Hollister #301, Santa Barbara CA 93117 USA. Telephone: +(805) 681-1300. Green Building Digest. Queens University of Belfast, 2-4 Lennoxvale, Belfast BT9 5BY Northern Ireland. Telephone: +01232 335466. Green Connections. PO Box 793, Castlemaine 3450 Australia. Telephone: +(03) 5470 5040. Home Power. The Hands-on Journal of Home-Made Power. PO Box 14230, Scottsdale AZ 85267- 4230 USA. Telephone: +(919) 475-0830. Joiners Quarterly. The Journal of Timber Framing and Traditional Building. PO Box 249, Brownfield ME 04010 USA. Telephone: +(207) 935-3720. Permaculture. Permanent Publications, The Sustainability Centre, East Meon, Hampshire GU32 1HR, England. Telephone: 01730 823311, internet: www.permaculture.co.uk . Positive News. The Six Bells, Bishops Castle, Shropshire SY9 5 AA. England. Telephone: + 01588 630 121/122. The Last Straw: The Grassroots Journal of Straw Bale and Natural Building. HC 66, Box 119, Hillsboro NM. 88042 USA. Telephone: +(505) 895-5400. e-mail: [email protected], internet: www.strawhomess.com .

153 RESOURCES 154 155

The Permaculture Activist. PO Box 1209, Black Mountain NC 28711 USA Telephone: + (828) 298- The Cob Cottage Company 2812. Workshops and resources in cob construction and passive solar design. PO Box 123, Cottage Grove, OR 97424 USA. Telephone: +(541) 942-2005, internet:

ORGANIZATIONS AND COMPANIES IN THE U.S. AND THE U.K. www.deatech.com/cobcottage Construction Resources Frank Andresen Specializing in ecological construction techniques. Exhibition center, resources, lectures. Construction with light clays and clay plasters; also offers dry clay products as well as workshops 16 Great Guildford Street, London SE1 OHS UK. Telephone: +020 7450 2211. and consulting. Constructive Individuals Kiefernstrasse 2, 4000 Dusseldorf, Germany. Telephone: +0211 7333216. Architects specialising in alternative construction, self-build projects, and construction workshops. Kevin Beale. London, UK. Telephone: +020 7515 9299. Design, consultation, and construction using earthbag, straw bale, and other methods. CRATerre-EAG School of Earth Construction Ty-Capel-Graig, Talsarnau, Gwynedd, Wales. LL47 6UG, England. Telephone: +(0) 1766 770 Maison Leurat, Rue du Lac, BP 53, F-38092, Villefontaine Cedex, France. 696, e-mail: [email protected]. CRG Design Healthy Homes Black Range Lodge Supplier of natural building materials. Design and consultation services. Videos, educational materials, and resources for straw bale, cob, and other alternative building Cedar Rose, PO Box 113, Carbondale CO 81623 USA. Telephone: +(970) 963-0437, techniques. Bed & breakfast lodging for educational retreats. e-mail: [email protected]. Star Route 2, Box 119, Kingston NM 88042 USA. Telephone: +(505) 895-5652, internet: www.epsea.org/straw.html Development Centre for Appropriate Technology Building code information and educational resources. Building Biology and Ecology Institute of New Zealand David Eisenberg, PO Box 27513, Tucson AZ 85726 USA. Telephone: +(520) 624-6628, e-mail: 22 Customs Street West, PO Box 2764 CPO, Auckland, New Zealand. Telephone: +(64-9) 358 [email protected], internet: www.dcat.net. 2202. Earth Hands & Houses, and PWA Architects California Institute of Earth Art and Architecture (Cal Earth) Design, consultation, workshops and construction of sustainable, ecological, 'organic' projects in Founded by Iranian Architect Nader Khalili to pursue research in sustainable human shelter developed and developing countries. principally through earthen materials and an earthbag technique called "Superadobe" for domes Paulina Wojciechowska, Architect. 18 The Willows, Byfleet, Surrey KT 14 7QY England. and vaulted structures. Apprenticeship retreats, and weekend visitations to the demonstration site. Telephone: + (0) 1932 352129, e-mail: [email protected], internet: Cal-Earth, 10225 Baldy Lane, Hesperia CA. 92345. USA. Telephone: +(1) 760 244 0614, e-mail: www.EarthHan.dsAndHouses.org. [email protected], internet: www.Calearth.org. Earthwood Building School Canelo Project Resources, workshops, and design consultations for cordwood-masonry construction, stone circles, Set up by the co-authors of The Straw Bale House. Offering comprehensive straw bale mortgage-free living, and off-the-grid energy strategies. construction workshops and educational resources, with a focus on traditional materials and Rob and Jaki Roy, 366 Murtagh Hill Road, West Chazy NY 12992 USA. Telephone: +(518) 493- practices including earthen plasters, floors, and bread ovens. Workshops in southern Arizona and 7744. Mexico. HC1, Box 324, Elgin, Arizona 85611 USA. Telephone: +(520) 455-5548, e-mail: Gourmet Adobe [email protected], internet: www.caneloproject.com Specializing in clay slips with mica and adobe. Carole Crews, HC 78, Box 9811, Ranchos de Taos, NM 87557 USA Centre for Alternative Technology Workshops and educational resources, with a large bookshop for alternative construction and Hartworks, Inc. sustainable living information. Producers of a two-hour video (see the Bibliography) available in U.S. standard NTSC VHS Machynlleth, Powys SY20 9AZ, Wales, UK. Telephone: +01654 702400, e-mail: [email protected], format. Includes a section on earthbags, as well as covering other natural building techniques. internet http://www.cat.org.uk Another video specifically on earthbag construction is in production. Kelly and Rosana Hart, Hartworks, Inc., PO Box 632, Crestone, CO 81131, USA. Telephone: +(719) 256 4278, e-mail: [email protected], internet: www.hartworks.com . 156 RESOURCES 157

Heartwood School Johnson Hill Road, Washington MA 01235 USA. Telephone: +(413) 623-6677. EQUIPMENT AND SUPPLIES Willbheart@aol. com Imagination Works Continuous berm machine for filling earthbags Dominic Howes, builder and consultant of alternative home construction using earthbags and Can extrude a continuous berm at rates of 10 to 50 feet per minute. "No trenching or stacking other alternative methods. required. With weight typically exceeding 100 pounds per foot, the continuous berm conforms RO. Box 477, Dragoon, AZ 85609 USA. E-mail: [email protected], internet: tightly to underlying soil surfaces, will not blow over, and is extremely difficult to dislodge from www.sfhet.net/imagination. original placement location. Additionally the berm can be cut into sections and stacked for stream- bank stabilization, 'sand bagging,' fluids containment, or used separately for check structures." Intermediate Technology Centre (description from Erosion Control journal.) Bookshop and educational resources. Available from Innovative Technologies, PO Box 378, 250 Hartford Road, Slinger, WI 53086- 103-105 Southampton Row, London WC1B 4HH, UK. Telephone +020 7436 2013. 0378 USA. Telephone: +(414) 644-5234. International Institute for Bau-Biologie & Ecology. Auro Products PO Box 387, Clearwater, FL 33757 USA. Telephone: +(813) 461-4371, e-mail: For casein, natural paints, oil solvents, waxes, and other finishes. [email protected], internet: www.bau-biologieusaa.com Sian Company, PO Box 857, Davis, CA 95617-3104 USA. Telephone: +(916) 753-3104, Joseph Kennedy internet: www.dcn.davis.ca.us/go/sinan/auroinfo.html or www.auro.de/ Architectural designer, writer, and peripatetic scholar of natural building and ecological design. Livos Phytochemistry of America Teaches, gives workshops and consultations. Natural, nontoxic paints and stains. Star Route 2, Box 119, Kingston, NM 88042 USA. Telephone: +(505) 895 5652, e-mail: 13 Steeple Street. PO Box 1740, Mashpee MA 02649, USA. [email protected]. Tel: 508 477 7955. www.livos.com for natural paints and wood finishes. OK OK OK Productions Livos UK Providing earthbag construction, training, along with workshops on wild clay and lime plasters, Unit 7 Maws Croft Centre, Jackfield, Ironbridge, TF8 7LS UK. Telephone: +0 1952 883288 earthen floors. Design consultations for dome and arch construction. Kaki Hunter & Doni Kiffmeyer, 256 East 100 South, Moab UT 84532 USA. Telephone: +(435) 259-8378, e-mail: [email protected]. Out on Bale by Mail (un)Ltd. Straw bale consultation, educational programs, wall raising supervision, and bulk orders of the book Build It With Bales (see the bibliography). 2509 N. Campbell, #292, Tucson, AZ 85719 USA. Sustainable Systems Support Design, consultation, workshops. Specializing in earthbag and straw bale construction methods. Source of printed and video resources. Carol Escott and Steve Kemble, PO Box 318, Bisbee, AZ 85603 USA. Telephone: +(520) 432- 4292, e-mail: [email protected], internet: www.bisbeenet.com/buildnatural/. Women Build Houses Workshops, referrals, and tool library. 1050 S. Verdugo, Tucson AZ 85745 USA. Telephone: +(520) 882-0985, e-mail: [email protected] . INDEX 159

finishes, 76, 83, 90, 97 finish stabilizers, use of, 79 materials for, 13, 38, 43-45 INDEX furniture, 114, 115 roofs for, 65, 71, 80 recycled bags, 44, 45 soil mix, 17, 46, 103, 107-108 design considerations, 13, 17, 29-33, 80 "seconds," 44, 45, 133, 140 thatched roofs, 68-70 Devon Earth Builders, 90, 106-107 small bags, 52, 137 Cob Cottage Company, 109 Devon Earth Building Association, 97 sources of, 19, 44 cold climates Devon Historic Building Trust, 108 earthbag buildings, 13-19. See also building orientation for, 31-32 disaster-relief housing, 13, 16, 43 damp areas, construction in; earthen plasters, effect on, 77 domes, xvii, 13, 14, 15 domes; waterproofing finish stabilizers, use of, 79 brick, 18 additions, planning for, 17, 32-33 hybrid house for, 128-29 buttressing, 26, 44, 54-57, 136 connecting, 13, 24-25, 136, 139 A beeswax, 119-20 cement insulation for, 111 compass for, 34, 48-49 design considerations, 13, 17, 29-33, acidic materials, 81, 83, 92, 106 benches. See furniture bond beams, 46, 79 lime plasters, application of, 87 corbeled, 27, 49, 110, 135, 140-41 80 additions, building, 17, 32-33 bentonite clay, 88-89 compression rings, 46, 79 soil mix for, 106 defined, 22, 26 in dry area, 35-37, 66 additives. See stabilizers binders. See also clay environmental impact, 46, 79, 89, 92 compass, construction, 34, 48-49 earthbags, construction using (See examples, 123-47 adobe, 4-8, 140 casein as, 98-99, 100 finish stabilizer, 46, 66, 75, 78-79, compression rings, 26, 46, 54, 57, 79, earthbag construction finishes (See finishes) bitumin, use of, 89 in limewash, 97 89-91, 100-101, 136 123, 125, 136 methods) labor intensity of, 13 cracks allowed, 105 in paint, 95 stucco, 90, 123, 127 concrete. See also cement earthquake resistance of, 15 layout of, 13-14 earthbag foundation, 38 as sealant, 93 cement-stabilized earthbags, 37, 38, 46, bond beams, 18, 60-63, 123, 127, examples, 123-26, 135-42 recycling, 17 finishes, 76, 80, 90 soil mix using, 103, 105-109 62, 89, 123, 144-45 130-34 form, use of, 49 seismic and structural testing, 14-15 floors, 118-19 bitumen, 79, 89 Center for Appropriate Technology, 15 foundations, 38, 127, 144-45 openings [See openings) shape of, 32-33 (See also domes) furniture, 114 bond beams, 15, 18, 46, 60-63, 66, 79, Ceramic Houses (Khalili), 21-22, 26 connectors. See passageways for roofs, 66 utilities, 32, 120-21, 139 roofs, 66 123, 127, 130-34 clay-based building materials, 5-6, 19, Constructive Individuals, xiv shell, determining thickness of, 27 Earthbag Construction (Hunter and soil mix, 17, 46, 103, 107 Building Biology and Ecology Institute 46. See also adobe; cob construc• corbeling, 16, 26-27, 43-44, 49, 110, spanned, 22 Kiffmeyer), 141 Africa, 6, 16, 18, 19, 22, 142 of New Zealand, 98 tion; straw-clay blends 135 on square structures, 27 earthbag construction methods, xiv, 4, Ahlquist, Allegra, 56, 127 building codes, 4, 14, 90, 105 as binder, 6, 103, 105-109 cordwood masonry, earthbag founda• stability, increasing, 49 13, 43-63. See also bond beams; alis, 95-97, 114, 141 Bunting, Adrian, 142 bitumen used with, 89 tion for, 38 thickness of shell, determining, 27 buttresses; earthbag fill; alkaline materials, 81, 83, 84, 106 burlap bags interior walls, floors, furniture, 103 costs, 13 doors. See openings foundations; hybrid construc• animal product stabilizers, 79, 82, 106 for earthbags, 18, 43-45, 76 moisture control and, 76 Ahlquist square house, Arizona, 127 drainage, 30, 37, 38, 75, 136 tion; openings apses, 22, 26 for insulation, 110 soil analysis, 80, 103-105 of earthbag bags, 45 earthen floor, 117 appropriate use of earthbags, 16-17 arched openings, 13, 14, 21, 22, 58-60 buttresses. See also tension rings clay finishes Escott-Kemble house, the Bahamas, gabions, 30, 39-40 cutting into bag, 17 arches, xvi, 13, 21-24, 138-39. See also for arches, 23-24, 57, 60 erosion of, 77 134 gutters, 140 forms, use of, 25, 49, 58-59, 144-46 vaults domes, 26, 44, 54-57, 126, 136 interior plaster, 92 Hunter-Kiffmeyer house, 141 dry areas, construction in, 35-37, 66 for furniture, 18, 114 for additions, 17 dry area, construction in, 35 as sealant, 93 Njaya backpackers" lodge, Malawi, dryboard, 109-10 keying, 36, 54, 137 buttresses for, 23-24, 57, 60 sand-filled earthbags, 49, 136 waterproofing, use for, 88-89 142 dry-stone foundation, 40 materials, 44-46 corbeled, 26 spring line, 23, 26 clay in earthbags, 13, 17, 18, 49 Tassencourt dome, Arizona, 125 simplicity of, 19 keystone, 23, 24, 59-60 straight walls, 127 cement stabilization of, 89 Yaquis vault house, Mexico, 145, 147 E structural walls of conventional lancet (catenary), 22-23, 44 damp areas, construction in, 35-38, CRATerre, 10, 78-79, 81 earth architecture, xiv, 3-19. See also house, 128-29 unbuttressed, 139 C 49 Crews, Carol, 82, 90, 95-96, 107 specific building methods, e.g. tamping, 52-54 Australia, 10 California, 14-15, 24, 34, 105 lime stabilizer use and, 83 adobe tools, 13, 46-49 California Institute of Earth Art and polypropylene earthbags, use of, 75 D clay-based building materials, 5-6 tying courses together, 49, 137 B Architecture (Cal-Earth), xiv- clay slip, 95-97, 114, 141 damp areas, construction in, 13, 35-40, history of, 3, 5, 6, 22 earthbag fill, 16-17, 49-50, 131, 140 bags. See earthbag bags xviii, 14, 43, 124 Cobber's Companion, The (Smith), 70, 49, 66. See also flood-prone revival of, 4-5 cement-stabilized (See cement- Bahamas, 16, 131-34 Canelo Project, Mexico, 71-72, 100, 116 104 areas, building in; waterproof• earthbag bags stabilized earthbags) , banana leaf juice, 81 casein, 82, 97-100 cob construction, 4, 5, 6, 8-9, 141 ing; water resistance cost, 45 filling process, 45-46, 50-52, 137-39 barbed wire, 36, 46, 54, 58, 137 catenary (lancet) arch, 22-23, 44 earthbag foundation, 16 finishes for, 75 making, 45 pH of, 81

158 i6o INDEX 161

earthbag fill, continued extenders (fillers), 93, 95, 103, 105-109, flood-resistant, 30-31 Hart dome house, 135-39 casein paint on 99 resistance to (See water resistance) procedure, 140 114. See also sand functions of, 34-35 Howes conventional-style house, making, 86-87 montmorillonite, 5-6 soil analysis, 80, 103 extensions, building, 17, 32-33 gabions, 30, 39-40 128-29 permeability of, 82-83, 90, 93 exterior finishes. See plasters width of filled bag, 45 ground, connection to, 35 pozzolanic additives to, 87-88 N external features, 18, 30, 32 Earth Building Association, 88 level plane provided by, 33, 47 I recipes for, 88 nailer boards, 114-15 Earth Construction (CRATerre), 78-79, for non-earthbag buildings, 16, 33, insulation, 142 water resistance of, 75, 90 natural building, xiii, 4 38 81 F earthen floor, 110, 111, 116 lime putty, 97 Njaya backpackers' lodge, Malawi, 142 earthen floors, 103, 107, 115-20 fiber. See also straw; straw-clay blend pumice-crete, 40-41 foundation, 37, 38 gypsum added to, 92 Nubian vault, 26, 59 alternatives to, 118-19, 127 in earthen plasters, 77-78 rubble or mortared stone, 39 roof, 70, 72-73 making (slaking), 84-86 construction, 118-19 interior finish plaster, 92 site preparation for, 33-34 scoria as, 136 mixing with sand, 86, 87 O heating in, 127 in lime plasters, 83-84 trench, 35-38 walls, 50, 110, 112-14, 139, 145 limewash, 95, 97-98, 100 Obregon project, Mexico, 25 walls, attaching to, 38, 39 insulation in, 111, 116, 117 in soil mix, 11, 106-109 interior finishes, 92-100 linseed oil off-the-grid, 32, 126 France, 9-10 layers, 116-17 fiber composite board, 109-10 interior partitions, 103, 109-10, 114-15 lime-wash additive, 97-98 oil, 81, 115, 117, 119. See also linseed oil maintenance, 119-20 fill. See earthbag fill furniture, 18, 30, 32, 103, 114-15 in oil-based paints, 100 oil-based paints, 100 repair, 120 fillers. See extenders (fillers) finishes for, 75 J as sealant, 93, 117, 119 OK OK OK Productions, 16, 140 sealants, 93, 117, 119-20 finishes. See also plasters; sealants; soil mix for, 106-107 jar test, 104-105 as stabilizer, 81, 89 openings, 26, 54, 57-60, 138-39. See for upper story, 118 stabilizers lintels, 18, 62 also compression rings Earthen Floors (Steen), 100, 119 casein, 98-100 G K living roofs, 65, 70-71, 140,141 arched, 13, 14, 21, 22, 58-60 earthen plasters, 66, 75-77, 80 floor, 93, 117, 119-20 gabions, 30, 39-40 kaolin, 5-6 love, role in designing of, xvii forms used for, 58-59 advantages/disadvantages, 76-77 interior, 92-100 geodesic structure, 130 Kemble, Steve, 16, 131-34 in hot climates, 110, 126 application of, 77-78, 91-92 keying in, 76, 86, 87, 126, 133 glass, 139 Kennedy, Joseph R, 15, 16, 18 M square, 57, 58, 60 clay slip (alis) finish, 95-97, 114, 141 maintenance, 77, 91, 100-101, 109 glue, casein, 82, 97, 98-99 keying maintenance Othona Community Retreat, xiv for furniture, 114 papercrete, 101 Gourmet Adobe, 82, 90, 96 of earthbag walls with barbed wire/ earthen floors, 119-20 Outram, Iliona, xiv, 14 interior finish use, 92 roof, 66, 73 gravel, 13, 30, 35-38, 46, 49, 50 branches, 36, 54, 137 finishes, 77, 91, 100-101, 109 ovens, 30, 75, 103, 114-15 maintenance, 77, 91, 100-101, 109 soil mix for, 106-107 Great Britain. See United Kingdom finishes, keying in, 76, 77, 86, 87, 126, Malawi, 142 overhangs, 32, 75, 76, 80 nonstabilized, cement plaster on, 90 spray application of, 76, 92 Great Wall of China, 9 133 manure permeability, 76, 80, 90, 93 fire protection greenhouse, 63 keystone, 23, 24, 59-60 lime/manure render, 88 P sealants, 80, 92-94 earthen plasters, 76 Guatemala, 15 Khalili, Nader, xiv, 14, 15, 21-22, 26, 34, manure/wheat flour/sand plaster, 82 paints, 94-100 stabilizers (See stabilizers) insulation, 110 gypsum, 81, 82, 86, 92, 114 38, 43, 124, 143 Mexico casein, 99-100 waterproofing, 66, 88-89 thatch, 70 Kiffmeyer, Doni, 16, 52, 131, 140-41 Canelo project, 71-72, 100, 116 clay slip (alis), 95-97, 114, 141 earth-filled tires, 39, 111 flood-prone areas, building in, 17, 30- H Hermosillo project, 16, 25, 56, 143— limewash, 95, 97-98, 100 Earthmother Dwelling Retreat, xvi-xviii 31, 38, 43, 49 Hartworks, Inc. (Kelly and Rosana L 47 oil-based, 100 earthquake resistance, 15, 38, 54-55, 62 floors Hart), 12, 16, 130, 135-39 lancet arch, 22-23, 44 Obregon project, 25 papercrete, 75, 135, 136, 138, 139 seismic testing, 14-15 alternative, 118-19,127 Hermosillo project, 16, 25, 56, 143-47 landscaping, 30, 31, 32 Save the Children project, 108-109 plaster mix recipe, 12 tire foundation, 39 earthen (See earthen floors) Hesperia Museum/Nature Center, 14, lime-based stabilizers, 38, 46, 78-79, mica, 92 properties of, 11-12, 101 Egypt, 6, 19, 22 Forschungslabor fur Experimentelles 24, 34 81-83, 86 Middle East, 9, 19, 22, 25, 32 as roof covering, 65, 66 electricity, 32, 120-21 Bauen, 15 hot climates, 31-32, 126, 132-33, 142 lime from coral reefs, 142 mineral stabilizers, 79, 82-83, 106 parapet-tie wall buttresses, 23 emergency relief, earthbags used for, foundations, 15-16, 34-41, 75, 76 Howes, Dominic, 16, 125-29 Lime in Building: A Practical Guide moisture passageways, 24-25, 136, 139 13-16, 19, 43 concrete, 127, 144-45 Hunter, Kaki, 16, 52, 131, 140-41 (Schofield), 87 barrier, 30 connecting, 13 environmental building, xiv, 3-4 in damp areas, 35-40 hybrid construction lime mortar recipe, 88 damage caused by, 90-91 passive solar. See solar energy erosion, 31, 32, 75, 76, 77, 106 details, 36-37 Ahlquist square house, 127 lime plasters, 66, 83-88, 136, 139 earthbag fill, moisture content of, 46 pH, 81, 83, 84, 92, 106 Escott, Carol, 16, 131-34 in dry areas, 35-37 earth and straw bale, 112-14 alkalinity of, 83, 84 earthbags, moisture wicked into, 17, plasters, 16, 19, 25, 126, 139. See also Europe, 9-10, 68. See also United dry-stone, 40 Escott-Kemble house, 16, 131-34 application, 86, 87 30 earthen plasters; lime plasters Kingdom earth-filled tire, 39 foundations, 16, 33, 38-41 capping earthen plasters, 46, 77, 80, permeability/evaporation of (See application of, 91-92 expomat mesh, 25, 145, 146 examples, 127, 132, 136, 144-45 greenhouse, 63 92, 93, 100, 114 walls, breathability) for burlap bag construction, 76 162 INDEX 163

plasters, continued low-cost flat, 71-73 spring line, 23, 26 tests, soil, 104-105 openings to, 58-59 damp-proof membrane, use of, 38, fragmentation of render mass, 91 metal, 145 square construction, 127 thatched roofs, 68-70 for roofs, 22, 66, 67 60, 70, 136 insulative, 111, 136 surface finishes, 66 square openings, 57, 58, 60 thermal mass, 31, 50, 91, 111, 113 three-vault house, 16, 25, 56, 143-47 earthen floor, 117, 119-20 interior finishes, 92 thatched, 68-70 squinches, 27 Three-Vault House, 16, 25, 56, 143-47 width to length, ratio of, 25, 67 roofs, 66, 68-70, 73 moisture permeability of, 76, 80, 90- timber poles, use of, 135, 138, 139 stabilizers, 46, 78-83, 98, 106. See also tie bars, 24 vegetable stabilizers, 79, 81-82, 106 sealants, 93 91,93 vaulted, 22, 66, 67 cement, finish stabilizer; timber, use of, 33, 62, 135, 138, 139, 144 ventilation, 32, 91, 139, 143-44 stabilization for, 88-89 for polypropylene construction, 75- water-catchment, 68 cement-stabilized earthbags; tires, earth-filled, 39, 111 water resistance. See also waterproofing 76 wind-resistant, 133 sealants Tlholego Learning Centre, South Africa, W clay-based soil mix, 106 sand/manure/wheat flour, 82 application of, 91-92 18 walls. See also thermal mass earthen floor, 119 soil mix for, 106-107 S lime-based, 38, 46, 78-79, 81-83, 86 tools, 46-49 breathability (permeability), 46, 76, papercrete, 12, 75, 101, 136 plates. See bond beams sand, 19 for waterproofing, 88-89 topography, 30-31, 34 79, 80, 82-83, 90-91, 93, 95, stabilizers for, 78-83 plumbing, 32, 120-21 in earthbags, 13, 35, 46, 49, 89, 136- Steen, Athena and Bill, 11, 108-109, trust in material, value of, xvii-xviii 106 wattle and daub, 4, 6, 10 polypropylene earthbags, 43-45 37, 140, 142 116, 119 fragmenting, preventing, 137 waxes, 115, 119-20 biodegrading, 17 in plasters, 82, 83, 86-87, 92, 139 stem walls. See foundations U interior partitions, 103, 109-10 weatherproofing. See waterproofing; cement stabilization of fill, 89 in sealant, 93 stoves, 30, 75, 103, 114 United Kingdom, 8, 68, 76, 107-108 retaining, 30, 39 water resistance; wind activity finishes for, 75-76 in soil mix, 103, 105-109, 114 straw Utah, 140-41 straight, 55-56, 60, 127-29 wheat flour paste, 81, 82, 96, 97 porches, 80 Save the Children Foundation project, in earthen plasters, 77-78 utilities, 32, 120-21, 139 water added to earthbag fill, 46, 47 whitewash. See limewash Portland cement, 78, 81, 89, 139 108-109 for insulation, 110 water-catchment roofs, 68 wind activity, 32, 54, 62, 80, 132-33 potassium silicate, 94 scoria, 38, 50, 130, 135, 136, 137-38 rammed, 111 V water glass, 93-94 windows. See openings pozzolanic material, 87-88. See also screed boards, 118 soil mix using, 103, 105-109 Vaughan, Sue, 130 waterproofing, 32, 36-37, 60, 75-76, 80, Wisconsin, 128-29 pumice screens, use of, 32, 80 straw bale construction, 4, 5 vaults, 14, 22, 24-26 141. See also drainage; finishes; prickly pear juice, 81-82 sculpting. See furniture earthbag foundation, 16, 33, 38 earthquake resistance, 15 flood-prone areas, building in; Y Pueblo De Sarmiento, 16, 25, 56, 143- sealants, 80, 92-94, 115, 117, 119-20 finishes, 76, 80 forms used for, 25, 59, 144-46 overhangs; water resistance Yaqui house, Mexico, 16, 25, 56, 143-47 47 seismic activity. See earthquake of furniture, 114 Nubian, 26, 59 bricks, 66 Pueblo Indians, 4, 5, 7, 90, 108 resistance hybrid earth and bale, 112-14 pumice, 37, 38, 49, 50, 73, 110, 114 Serious Straw Bale (Bergeron and for insulation, 72-73, 111-14 pumice-crete, 38, 40-41 Lacinski), 70 roofs, 71-73 sick building syndrome, 79, 95 straw-clay blends, 6, 10-11, 37. See also Q site cob quark, 88, 99 landscaping, 30, 31, 32 for furniture, 114 locating building on, 13, 29-32 for insulation, 72, 110, 111 R preparation, 33-34, 47 string lines, 34 rammed earth, 5, 6, 9-10, 38, 76 topography, 30-31, 34 structural testing, 14-15 rammed straw, 111 slaking, 84-86 stucco, 90, 123, 127 reinforcement rods, 25-26, 38, 54, 142, sloping site, 34 subfloor, 117 145, 146 Smith, Michael G., 70, 104 sun, location related to, 13, 31, 80 remote locations, earthbag use in, 13, sodium silicate, 93-94 Superadobe, xiv, 16 43 soil for building materials, 80, 103-9. sustainable building, xiv, 4 renders. See plasters See also clay-based building Sustainable Systems Support, 16, 131 roofs, 65-73, 80 materials; earthbag fill; sand adobe/brick, 66 solar energy, 31, 110, 127, 128, 139 T conventional, 68, 127 solid buttresses, 23 tamping, 47, 52-54, 139, 140 earthbag foundation for, 33 South Africa, 16, 18 Tanzania, 142 insulation, 70, 72-73 southwestern United States, 6-7, 11-12, Tassencourt, Shirley, 123-26 living, 70-71, 140, 141 14, 19, 90, 123-27, 130, 135-39 tension rings, 26, 36-37, 54-57