Woodless Construction Using Unstabilised Earth Bricks and Vault
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Woodless Construction Using unstabilised earth bricks and vault and dome roofing in West Africa Development Workshop 1998/2002 Woodless Construction............................................................................................................................................1 Preface.................................................................................................................................................................1 1. Introduction ......................................................................................................................................................1 1.1. The issue...................................................................................................................................................1 2. General considerations....................................................................................................................................2 2.1 Experience of earth roof construction without wood or shuttering.............................................................2 2.2 Technical options .......................................................................................................................................4 2.3. Woodless construction technology............................................................................................................5 2.4. Aspects requiring further development or improvement ...........................................................................9 4. How to choose the appropriate technical option............................................................................................11 4.1. Required material properties...................................................................................................................11 5. Case study: woodless construction in the Sahel ....................................................................................13 5.1. Background .............................................................................................................................................13 5.2. Earth building and earth roof building in the area ...................................................................................14 5.3. What modifications have been made to the original technologies?........................................................16 5.4. What the impact has been.......................................................................................................................18 6. Ecological and economic comparison with other buildings ....................................................................19 7. A final observation .........................................................................................................................................20 Bibliography .......................................................................................................................................................20 the same time, in the form of vaults and domes. Domes in the form of thin earth shell dwellings and Woodless Construction stores in abounded in central and western Africa, whilte substantial masonry domed and vaulted structures have exeisted for centuries in North Preface Africa and the Middle East. Stone and fired brick masonry domes and vaults were equally chosen by This document is extracted from Lund Building builders in Europe to provide durable structures, Series, Volume 9 N° 2 issue on Woodless and corbelled stone domes can be found in many Construction, which was part of the institutional co- areas of Europe. operation between Lund Centre for Habitat Studies, Where the shortage of wood was extreme, as in the (LCHS), funded by the Swedish International deserts of Iran or along the Nile valley, not only Development Co-operation Agency, Sida. Building Issues is directed to planners, architects, engineers and technicians working in central or local government, non-governmental organisations, private companies, universities, research institutions and development aid agencies. 1. Introduction 1.1. The issue Earth is one of the first building materials used by man and even today a large share of the dwellings in the world are constructed with earth. Earth was the most commonly used building material in Europe until the middle of the 19th century. Today one finds modern earth construction on a small Figure 1: Yazd city with vault and domes scale only in Europe and USA as a type of roofs in Iran ecological housing in order to create sound and were earth domed and vaulted roof structures sustainable environment. The use of earth as developed thousands of years ago, but the building material has often been connected to the techniques that developed enabled the roof to be lack of wood. This is common particularly when it built without any supporting formwork during comes to low-income housing in developing construction. This meant that hardly any wood was countries because of lack of wood or because one needed during construction, and none in the cannot afford to pay the cost of wood or non local finished structure. In both Egypt and Iran and their alternatives. neighbouring countries, a roof building technology 'Woodless Construction' has been developed in the developed that made use of earth as a readily Sahel during the last 20 years by Develoment available local material and responded to the Workshop and its partners. This experience is absence of timber for building, allowing builders to interesting since a continuous development of construct a very wide variety of structures that in technology has taken place responding to actual addition could contribute to good climatic comfort, functional and technical needs and limited and good quality and durability. economical resources. The same problem of scarcity of trees has been encountered in the 20th Century in the Sahel Context: countries of West Africa. Apart from the thin earth In many regions of the world shelter has shelled granaries, wood and branches traditionally traditionally been achieved with earth walls and with provided the support or the reinforcement for the flat or sloping roofs that are made of timber also majority of buildings and their roofs. However, over- covered by earth. The buildings produced with consumption and drought have led to a drastic these materials have ranged from simple shelters to depletion of the tree resources in the immediate structures of great sophistication and quality. sub-saharan region known as the Sahel. The The attractiveness for many builders was that the problems are essentially: earth and the wood were materials easy to obtain • increased demand for resources by a and use, and affordable. In many instances, both growing and more sedentary population; could be collected for little or no cost. However, • the lack of resources at two levels: whilst a variety of materials have been used for increasing scarcity of organic resources; building walls, where timber was not readily and shortage of financial resources to pay available to provide the structure for roof building for alternative non local products, there were fewer alternatives: one answer was to • the negative effect that tree depletion has build roofs where the material for covering - such as on the environment and the future of the stone or earth - provided the supporting structure at region. 1 The Sahel thus typifies many other parts of the supporting formwork,and with hand made world facing similar environmental decline and unstabilised earth blocks. Woodless Construction is poverty in Afirca and Latin America, and in those the name that has been given in the Sahel region of countries where the problem has already existed for West Africa these techniques for the construction of many centuries (Iran, Egypt, Afghanistan,). vault or dome roofed buildings using ordinary hand However, the perception of these overall problems moulded and sun dried mud bricks. is not always the same and locally concernt about It describes the woodless construction building the environment and the disappearance of tree techniques and the criteria that led to their choice, cover is rarely a priority. There is more concernt and to consider the process of how these about cost and the difficulty in obtaining materials to techniques had been introduced and adapted. The build with. Solutions that stand a chance of case study underlines that the techniques have to adoption have to combine affordability, quality, be adapted to very local contexts, and that their is ease of use and durability. no one standard method that can be applied. Amongst the many technical and material options for roofing that could replace traditional practices 2. General considerations few are acceissbile to poor communities because of cost. Non-local or imported resources are frequently not affordable, whilts cheap options, 2.1 Experience of earth roof such as corrugated roof sheeting, often do not on construction without wood or their own provide the same climate protection that shuttering was achieved with the traditional wood and earth roof or by thatched roofs. Origins Masonry vaults and domes built without formwork Woodless construction has therefore aimed to have their roots in a long tradition of building in the bridge the gap between accessibility and arid areas of the Middle East, as distinct, for affordability and quality, and to provide a durable example, from Roman vault structures that required roofing system, using materials that are locally a supporting formwork during