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Chilterns Buildings Design Guide

Supplementary Chilterns Technical Note

an Area of Outstanding Natural Beauty 2 Chilterns lint

Acknowledgements All photographs are by Dr. James Moir unless Tim Amsden, Mike Jones, Les Mathias and Lynn otherwise acknowledged. Mathias (Flintworkers) Martin Andrew ( Council) The drawings on page 7 are reproduced from This Technical Note has been published by the Dan Bosher (Boshers of Cholsey Ltd.) “Records of ”, Volume 31, Chilterns Conservation Board which would like to Richard Bossons (Architect) 1989, pages 56 to 59, with kind permission of express its sincere thanks and gratitude to Dr. John Bysouth (The Stone Federation of Great the Buckinghamshire Archaeological Society. Britain) The drawings on page 20 are by Derek Rogers James Moir who has researched and written this Eric Cheeseman (Bovingdon ) RIBA. The drawings on pages 35 and 36 are by Note. Thanks should also go to the members of the Russ Craig (BEAMS) Nicola Westbury and are reproduced from “Care and Flint Advisory Group who have given George Crutcher (South District and Repair of Flint Walls”, Technical Pamphlet generous help and advice; to Peter Cave (Johnston Council) 16, with kind permission of the Society for the Nick Doggett (CGMS Consulting) Protection of Ancient Buildings. Cave Associates) for making his research freely Roger Evans (Former Buckinghamshire Historic available; to Eddie Fincken for practical guidance Buildings Officer) The Chilterns Conservation Board also wishes to and demonstration; to the local authority Planning Mike Farley (Former Buckinghamshire County acknowledge the generous grant aid made Officers who have contributed through the drafting Archaeologist) available by the following organisations towards Douglas Kent (SPAB) the cost of producing this Note: and public consultation exercise, and to Colin Gary Marshall (Regional Archaeologist, National White, Chilterns AONB Planning Officer, for his Trust) The Countryside Agency, South East help in organising the Group and input into Jim Matthews (HG Matthews Brickworks) Development Agency, Council, revisions to the text. Peter Melvin (Architect) South Oxfordshire District Council, Dacorum Nigel Oxley (North District Council) Borough Council, South Bedfordshire District Richard Oxley (Oxley Conservation) Council, Wycombe District Council, Bovingdon Particular thanks are also due to the following: Ian Pritchett (IJP Building Conservation Ltd.) Brickworks Ltd, Dunton Brothers and H. G. Steve Rodrick (Chilterns AONB Officer) Matthews. Derek Rogers (Architect) Linda Stone (Chiltern District Council) Sir John Johnson Christopher Vane (Symm & Co. Ltd.) Chairman Chilterns Conservation Board Martin Warner (Dunton Brothers Brickworks) Simon Went (South Bucks District Council) Chilterns Buildings Design Guide - Chilterns Flint, and the owners who allowed their buildings to be Supplementary Technical Note c Published May 2003 photographed, particularly the Trustees of Sir No part of this publication may be reproduced or transmitted in Paul Getty for permission to use photographs of any form without the prior permission of the Chilterns the Wormsley Estate. Conservation Board.

ISBN 0 -9545242-0-9 Chilterns lint 3

oreword Contents

This technical note on the use of flint Sadly this special character is often lost due Chapter 1 augments the Chilterns Buildings Design to the increasing use by builders and Introduction 4 Guide which has been adopted by many devolopers of standard designs and non-local planning authorities in the area. Its aim is to materials. Even when flint is used, poor Chapter 2 inform and help all those involved in the execution and minimal materials often Background 6 development process by providing additional, detract from the appearance of the finished The Material 6 more detailed guidance. building. Historical Use of Flint in the Chilterns 7

The glory of the English countryside lies in its Within the Chilterns there are numerous Chapter 3 Using lint Today diversity. Travel for only a few hours and you examples of how our forebears were able to 14 marvel at the subtle changes in landscape and build in such great harmony with the An Inspirational Inheritance 14 Regional Distinctiveness 16 in building design and materials. In the landscape. That harmony is what this Survey 18 Chilterns the use of flint as a building material supplementary guidance is meant to achieve. Specification and Design 20 is a distinctive ffeature and was for centuries Designing with Flint 23 a basic building material, creating buildings Design and the Choice of 26 which people like to see. Today it is still Material Combinations 29 valued and can greatlt add appeal to new Designing with Existing Flint 34 buildings. Sir John Johnson Chairman, Glossary 38 Chilterns Conservation Board May 2003 Bibliography 39

Further Advice 39 4 Chapter 1 : Introduction

Chapter 1 Introduction It may offer assistance to local authorities with the 1.3 To this end, the Chilterns Buildings Design aim of ensuring their policies and practices are co- Guide was published in 1999 to provide guidance ordinated and consistent with guidance that has on how to achieve high quality design in new 1.1 Flint is associated with the chalk band been adopted. developments. The Guide provides a framework stretching across South-eastern England from for protecting and enhancing the identity East Anglia to Dorset and the South Downs. of the traditional built character of the The are formed by an outcrop of this M1 Chilterns, which has been steadily chalk on the north-western side of the eroded by the use of standardised basin. Hitchin designs and non-local materials. This Dunstable Technical Note is one of a series that 1.2 Much of the Chiltern Hills is designated an Luton are intended to supplement the Area of Outstanding Natural Beauty (AONB). The Chilterns Buildings Design Guide by shadow Chilterns Conservation Board is providing additional guidance on the responsible for conserving and enhancing the appropriate use of locally available natural beauty of the AONB, increasing the Aylesbury materials. (see the Chilterns AONB website understanding and enjoyment of its special for details of other Technical Notes). qualities, and fostering the economic Berkhamsted Hemel and social well-being of local Hempstead Princes St Albans communities within the AONB. Risborough

M40

River Thames A cluster of flint buildings with distinctive and traditional character () Beaconsfield Wallingford

Marlow

M25 Henley-on-Thames Goring River Thames Chapter 1 : Introduction 5

applications. Local planning authorities will be 1.4 The Objectives of the guidance are to: invited to adopt it as Supplementary Planning Guidance to the relevant development plans so as l Raise awareness of the quality of the to ensure consistency across the 15 local planning traditional built character of the Chilterns authorities within which the AONB lies. Once AONB by highlighting the importance of adopted the local planning authorities will expect flint, its characteristics, functions and uses all relevant planning applications in the AONB to demonstrate how these guidelines have been l Foster an interest in and create respect for taken into account. Adherence to the guidelines the historical diversity of flint buildings in does not mean that development proposals will the region necessarily be approved because other planning policies in development plans will apply. Specific l Re-establish traditional character in areas of Garden shelter The Pavilion (Wormsley) design and planning guidance is also likely to the AONB where it has been damaged or (Chipperfield) apply to buildings which have been listed or are eroded intended to be used, and also gives guidance on situated in conservation areas. The local planning repair of existing flintwork. It is not a authority should be contacted for details. l Protect the distinctive character of the built comprehensive historical and design statement. environment by encouraging good repair Nor is it meant to imply that all new designs must 1.8 This note was the subject of public practices utilise only flint and slavishly copy buildings from consultation prior to adoption. The views of previous eras. It illustrates a potential for consultees were taken into account and in some l Encourage the sustainable use of a local, excellence, diversity and flexibility in new design cases changes were made. A copy of all natural resource whilst still respecting the distinctive qualities of representations made during the consultation the area. period and the Conservation Board’s response is l Promote the appropriate use of flint in new available from the Chilterns AONB office. developments so as to create respect for the 1.6 This guidance is intended to be used by all traditional built character of the AONB involved in the development process: owners; New Church Hall 1.9 Flint is one of a small group of favoured local (Chipperfield) architects; designers; developers; builders; building materials, but it is still l Encourage flint workmanship of the highest planning authorities; parish councils and any seen as difficult to acquire, standards to inspire high quality design in organisation or individual with an interest in the difficult to convert, and difficult new developments built environment of the Chilterns AONB. and expensive to build with. This note is intended to redress 1.5 The note covers all types of new buildings, 1.7 The note is not a statutory document, but will the balance. extensions and conversions where flint is contribute to decision-making on planning 6 Chapter 2 : Background

Chapter 2 Background 2.5 A notable characteristic of buildings in the

Pebble AONB is the consistent use of from both the The Material chalk strata and the overlying clay with flints. Flint The Chilterns appears in buildings in its natural form as smooth, 2.1 Flint is found in most of the chalkland regions amorphous nodules, but also as bruised boulders, of England and is one of the most widely fractured fragments, smooth cobbles, and split or available, naturally occurring stones found in Flint knapped pieces. southern Britain. Its mineral content, composed of Pebble crystalline silica () and hydrated silica (opal) Cortication gives its core a smooth, often jet black texture with an almost vitreous lustre. 2.6 A newly quarried chalk flint, known as ‘virgin’ or ‘raw’ flint has an opaque white outer crust 2.3 Flints are found embedded within the Upper known as the cortex or ‘rind’, where the flint has 2.2 Flint is thought to be the remains of sponges Chalk, and in the top strata of the Middle Chalk become porous. When split, cortication affects the that grew on the floor of the Chalk seas, filtering immediately below. They take many forms, though newly exposed surface which initially may show the water around them for food particles. When a they most commonly occur as random, separate as a transparent milky film over the core, sponge died, it literally dissolved away and the nodules up to 60cm (2ft) across. Typically they are eventually darkening on exposure to produce ooze left behind would be trapped in the chalk and sinuous, amorphous lumps, often with knobbly shades of beautiful blue-grey. slowly harden into flint. Often, flints contain the protuberances and sometimes perforated. fossils of other sea-creatures. Field flints 2.4 Although all flint originated in the chalk, Quarried chalk flints erosion over millions of years has freed nodules from this initial setting. Glacial drift has left clay- with-flint deposits overlaying much of the Chilterns. These processes inevitably have tended to change the stone’s appearance, hence ‘derived’ field flints found in the Chilterns tend to be stained brown and often possess their original, eccentric contorted shapes, or they may be fractured by exposure to frost, sun, and agricultural machinery. Chapter 2 : Background 7

Patination Flint was used for a variety of purposes tranchet microlith piercer saw backed knife scraper 2.7 Some corticated flints are characterized by a chopper notched flake waxy sheen, typically yellowish-white; the patina is acquired through the assimilation by the surface pores of the cortex of new silica derived from soil water, a process that ceases naturally once a surface film has closed the pores. Patination is a very slow process and implies great antiquity. 2.10 Due to its ready availability and cheapness, flint may have been in continuous use as a Secondary Coloration all from prehistoric building stone in the Chilterns for over two In the town walls, bands of facing flint alternate site at millennia, though the extent of its use and the with narrower layers of thin and tiles. Stratford’s Yard, Chesham 2.8 In both forms, flint is liable to secondary status of buildings on which it was used have The flints used in the Roman villa at Latimer Records of Buckinghamshire coloration into shades of brown, amber, yellow or fluctuated over time. (C2nd-C4th) were probably collected from the Volume 31 1989 grey through the percolation of its pores by iron surrounding ploughed fields. oxides or other chemicals from the surrounding 2.11 Archaeological evidence for the early use of clays; such coloration of the core is much slower flint in the area is surprisingly sparse. Remains of The walls of Verulamium - an early example of the use of flint than the staining of the cortex. possible Neolithic flint mines exist at High Wycombe and Dunsden; depressions on Pitstone Hill are now thought to be the legacy of medieval Historical Use of lint in and later chalk extraction. Later workings possibly the Chilterns survive at , and Emmer Green; but for general building purposes 2.9 Flint is a very resilient stone. It can be struck flint has mostly been a by-product of quarried against metal to produce sparks (hence ‘flintlock’) chalk or picked up from the fields. or used as an ideal subsurface for making roads. Flint also fractures easily to produce flakes which 2.12 Where early examples survive, such as the can be fashioned into , and theatre at Verulamium, flint walls have two parallel scrapers, or it can be used to make flintglass. leaves bonded at intervals with long flints but with a central void mostly filled with flint rubble. 8 Chapter 2 : Background

2.13 Any church in the 2.14 In the early medieval period, flint walls were suited to splitting, so by Chilterns with surviving commonly limewashed or rendered externally (as the C14th walls were medieval fabric utilises flint. are parts of and Church). being faced with Some incorporate re-used Probably for this reason, examples are found irregular knapped flint. Roman bricks, as at St incorporating a random mix of materials, some re- (i.e. where the flint Albans Abbey. At used. As this practice ceased, the quality and nodules have been split Berkhamsted , only appearance of flintwork became more important. to expose a flat surface). the flint infilling survives to At the same time, chalk was being quarried for More decorative work what would have been even agriculture and building, yielding virgin flint began to emerge in the more massive walls, the middle of the C14th and th outer leaves of smarter Chequerwork with knapped flint (Luton) by the C15 flintwork Early medieval stonework having been robbed over the was generally more rendered flint walls (Fingest Church) years and re-used elsewhere in the town. carefully selected, Domestic example of Anglo-Saxon (parts of St Mary’s graded and coursed, chequerwork (Flamstead) Northchurch and Little Missenden are often with fully knapped thought to be pre-Conquest) and Norman faces (i.e. squared so walls show a predominance of mortar with that they fitted together rather like bricks). fragments of brick and stone rubble, together with unfractured nodules of flint, 2.15 By the C16th, as church building declined, scattered haphazardly or roughly coursed in flint began to be used more widely in domestic the face of the walls. By the C11th, buildings. Chequerwork, used on churches in the quoins and dressings began to appear C15th percolated down into domestic buildings; in (brick was little used for dressing flint timber-frame buildings, flint continued to be used before the mid C16th). Totternhoe stone was in plinths (as seen in medieval barns for example) particularly favoured and is found in many but also for a short phase was popular in early Chiltern churches. By the early C13th, chimney stacks. Small ancillary buildings of flint proportionately less mortar was being used may once have been more common, but none and after c. 1250, flints began to be laid in survives from this period. more regular courses. Chapter 2 : Background 9

Old ManorHouse, c.1602 (Hambleden) Lodge Farm () House dated 1691 (Mapledurham)

C17th flintwork. The Old Manor House at Hambleden was rebuilt in 1602 in flint with narrow brick dressings. Within a few years, nearby Burrow Farm had an imposing flint and brick Early C19th brick front, flint side walls (Chinnor) extension of two storeys and an attic added to the timber-framed farmhouse

2.17 Increasingly, flint and brick were being used to encase former timber-framed buildings, and rear service wing extensions of brick and flint also Burrow Farm, c.1605 (Hambleden) begin to appear. Early dated examples of complete flint-walled houses can be seen at Lodge Farm, Bockmer and Mapledurham, the latter dated 1691. 2.16 As timber-frame construction steadily went Brick however, predominated; when the two are out of fashion, brick rather than flint became the found together, there was often a tendency to hide favoured material in the Chilterns. The region can the side and rear walls of flint behind a brick th still boast some fine examples of late C16 and façade. 10 Chapter 2 : Background

2.19 Though it never surpassed the numbers of pure brick buildings, the emergence of unknapped flint on more modest buildings is ironically closely

tied with increasing brick Flint bridge (West Wycombe Park) production in the eighteenth and nineteenth centuries. Thick beds of flints random rubble flintwork to house an increasing overlying the brick earths provided a ready and rural workforce. In these more ‘humble’ examples, abundant source of material. Often the most the walls were constructed of flint rubble, the Folly (West Wycombe) extensive developments of brick and flint cottages flints being simply bonded together using mud were on the brick fields themselves, as at rather than lime mortar. 2.18 In the eighteenth century, as church or , Buckland Common or Lane End. chapel building tended to opt for brick, secular 2.20 Two further reasons account for the landowners perpetuated the use of high quality As these areas of former common-land were increased use of flint in the C19th. First, farmers flintwork, particularly in the use of knapped and colonized, numerous small cottages were built of paid to have flints picked of their fields to make squared flints. This rarely applied to their country houses but instead was increasingly employed for estate buildings and structures in landscape garden designs – inspired no doubt by the particularly ebullient designs which mushroomed at West Wycombe Park. Gothick cottages, gazebos, grottos and follies often appear as exotic, romantic counterpoints to the formal design of the classical house. Examples of decorative flintwork on quoins is a local adaptation of the more common rock faced stone features in Classical buildings elsewhere. This example of a small flint cottage at Totteridge was typical of many dotted around the commons Former house of brickyard foreman ( End) (Courtesy Wycombe Museum) Chapter 2 : Background 11

ploughing easier. Secondly, 2.21 All these factors prompted roads (the maintenance of which the gradual emergence of flint- remained a parish responsibility with-brick as the predominant until 1888) were steadily Chilterns ‘style’. The C19th was improved. Vast quantities of perhaps the heyday for flint, a flints were picked off ploughed marked contrast emerging fields for road maintenance as a between ‘polite’ and means of employing those who ‘vernacular’ buildings. Many qualified for parish relief, often smaller houses, cottages and women and children. Payment farm buildings were built with was 8d to 1/- for a cubic yard of rubble flint facings tied to Small cottage () flints. Stone breakers were backings of brick or, employed to split these flints for Charles Delderfield, stonebreaker, occasionally, chalk. Villas, flintwork. Flint was seen as particularly born 1843 () road use, a practice which may industrial and public buildings appropriate for Gothick buildings. It also appears have stimulated use of more often incorporated conscious in urban contexts in the Chilterns – Wycombe has knapped flints in buildings. expressions of ‘manufactured’ nice examples at Castle Hill House, the Flint Cottage on Crendon Street (excruciatingly pointed) and the old Post Office in Easton Street.

St Crispins, West Wycombe, a splendid Gothick residence built for the local shoemaker

An example of urban flintwork (Nos 14 & 15, Easton Villa Street, High Wycombe) (Castle Hill House, High Wycombe) 12 Chapter 2 : Background

2.22 The Chilterns can in the C19th in particular, black mortars, using boast examples of churches additives such as coal or brick dust, soot or ash or other institutional were used to give a definite visual effect. buildings designed or Terraced housing (Woodside) remodelled by the majority of pre-eminent Victorian 2.23 Small clusters of flint buildings became architects. Inspired by commonplace in the C19th. Terraces also started to English regional Gothick appear, some of considerable length and precedents, they uniformity. Many country estates used flint for experimented with bold new cottages in villages such as Hambleden and uses of flintwork, elaborate Bradenham, perpetuating its use well into the late brick diaper patterns and C19th. Estate boundary walls as at Assendon, occasional polychromy. Tring Park and Markyate Cell employed estate They occasionally borrowed labour to impressive ends. Some landlords – traditions from other particularly those ‘rooted’ in the Chilterns - regions, such as knapped embraced flint and a large estate such as at West from E. Anglia. Prestwood Church, 1849, part of a cluster of buildings by E.B. Lamb Wycombe deliberately cultivated and Quoins of imported experimented with idiosyncratic forms of flintwork. A fine example of C19th stonework re-appeared Other estates consciously rejected it, for example flintwork although in the Wycombe area, the locally the Bedford Estate at , or the Rothschilds (St Michaels Lodge, available Denner Hill stone was favoured. The St Albans) in Tring and the surrounding area. former Brewery at Amersham used galletted flint chips (not a common tradition in the Chilterns) - Estate Cottages (Hambleden) variations occur on the churches at Medmenham and Boveney. Some smaller buildings displayed Use of dark mortar (Castle Hill House, bottle ends set in flints. Experiments were made High Wycombe) with colouring mortars. Early lime mortars, using local chalk, gave little or no hydraulic set; by the end of the C18th stronger hydraulic limes were becoming available, and Bottle ends (Coleshill) Chapter 2 : Background 13

Flintwork in new developments often uses traditional skills. However, there has been a recent growth in the use of pre- 1947 housing, with well executed new extension of knapped flint to left (Fingest) cast blocks with flint inserts, whose use does not 2.24 In the first half of the C20th, flint in the require traditional skills. Chilterns continued to be used in church- Fortunately the regional craft buildings, for semi-detached houses and traditions have not been extensions to farmhouses. By mid-century, its obliterated and they should be nurtured whenever new projects use was declining, although some rural housing The new Library ( Wormsley) continued to adapt the use of flint to are being undertaken. The Library (Wormsley) contemporary designs. Flint remained popular for Flint and brick revivals (Lacey Green) boundary and garden walls and from the 1960s it began to re-appear in institutional buildings. An 2.25 But the major use of flint in the Chilterns interesting experimental design dating from 1968- has been on the Wormsley Estate where in the 9 is the hall extension to St Mary’s Church at late 1980s a major new building project involved Luton. the construction of 2,000 sq. metres of new flintwork, a remarkable showcase of techniques and styles ranging from the most humble grade of flint to the most sophisticated.

2.26 As awareness of the loss of local character grew in the C20th, the ‘traditional’ flint and brick house was revived by developers and builders with varying degrees of success. Some blend extremely well into their village surroundings but too many incorporated incongruous token panels in predominately brick-built buildings – a trend which still persists in some new design work.

A one-off design (St Mary’s, Luton, 1968-9) 14 Chapter 3 : Using lint Today

Chapter 3 Using lint Today

An Inspirational Inheritance Mausoleum (West Wycombe)

3.1 Buildings and structures of every shape and size have been constructed from flint, enriched by If the flints are already there the many combinations of other materials it is some of the extra costs may encountered with. Conventional stonework often be offset, and the ecological Church (Flaunden) Farm buildings (Lodge Farm, Bockmer End) aims for consistency and uniformity but the benefits are manifest. characteristics of flints – their shape, colour and no fuel to convert it, it can even sometimes be free. Moreover, flint can add value texture - invest them with a vibrancy quite unlike Building in flint is undeniably expensive because to new buildings. Outhouses other stonework; the beauty of flintwork lies in its of the extra time and care it calls for. As a general (West Wycombe) potential for creating a spectrum from precise rule, in a standard 3-bedroom house, external 3.3 Yet today, flintwork tends blockwork using accurately knapped flints with walling costs fall between 10-15% of the overall to be confined to ‘token’ or thin joints to a more random, ‘rustic’ appearance building costs. This will increase if flint is used. pre-cast panels, often with more cement than flint Former School () using unfractured, amorphously shaped stones. However, this will be more than justified by the left showing. It is aesthetic benefits and durability of the material. sometimes claimed 3.2 For building requirements in the Chilterns, the there are few skilled supply of flint is as good as infinite; it is local, practitioners; but poor reducing transport costs; it takes little effort and specifications and designs are as much at fault for producing Farmhouse visually poor results. () The projects on this page nevertheless illustrate how these limitations can successfully be overcome.

Bus Shelter (Ewelme) Former Workhouse & Hospital (Amersham) War Memorial (Lilley) Town House (Watlington) Token flint panels Chapter 3 : Using lint Today 15

3.4 Flint offers great design potential; when using it, a comprehensive project brief should:

l respect regional distinctiveness l be based on a comprehensive local survey l specify appropriate methods, skills and Sundial base of knapped materials to achieve flintwork of the highest and squared flint (Stoke Row) possible standard

New entrance front to Fawley Rectory, by Quinlan Terry

Extension to Verulamium Museum (St Albans)

Well designed new flint buildings should dovetail into the surrounding landscape and settlement The Library (Wormsley) pattern ()

Extension to Chorleywood School Sensitive new housing with a balanced use of Extension to St James Church (Aldbury) Extension to Kensworth Church traditional materials and design (Lacey Green) 16 Chapter 3 : Using lint Today

Regional Distinctiveness 3.6 Flint is by no means the most widespread of traditional walling 3.5 This note has already emphasised the wide materials in the Chilterns area, historical application of flintwork in the Chilterns. featuring in less than one third of domestic buildings. The majority date from the C19th. Some dramatic urban examples of flint buildings are found, but often its use is confined to rear and side elevations, backyard buildings and walls, or to buildings Flint boundary walls are found throughout the Chilterns on the margins of settlements.

3.7 Within a region the size of the Chilterns, there western scarp; dressings of yellow ‘stocks’ are are inevitably subtle local variations – in the more often encountered in the north-east of the south-west, examples of banded flintwork can be region; whilst in North Hertfordshire brown- Farm buildings (Kensworth Corner) found; thatch and flint are more common on the coloured bricks were prevalent. Examples of flint construction are found throughout the AONB, although prevailing geological conditions will affect relative densities. Flint boundary walls, a defining characteristic of many Chiltern settlements, are ubiquitous and a fair number of farm buildings survive throughout the area. Barns tend to use flint for plinths, while flint and brick is found used in stables, cart sheds and pig-sties. Domestic examples tend to fade away both in the north of the area (north of the A41 gap) and in the extreme south-west of the AONB – dwelling houses and farm buildings therefore occur with greater frequency in The nineteenth century was the heyday for flint and brick Banded flintwork is only found on the south-western Buckinghamshire and Oxfordshire. ( Common) fringes of the Chilterns (Benson) Chapter 3 : Using lint Today 17

Regional Distinctiveness Checklist

l Do respect distinctive Chiltern traditions The painted flintwork and thatched roof is unusual in the Chilterns l (Ellesborough) Do combine flint with locally-made bricks l Do combine flint with clay peg-tile and natural roofs l Do use lime-rich mortars and coarse aggregates l Do experiment with appropriate, regional Chalk-rich mortar techniques

l Don’t use pebbles/cobbles Pebbles are not commonly used in the Chilterns l Don’t paint, render or tar new flintwork l Don’t dilute local character by importing Local brick, tile and flint (near ) alien styles - use galletting, banded flintwork and flushwork sparingly and only if there is good local precedent

Yellow bricks are sometimes encountered, Brown coloured bricks are common in particularly in the north-east of the region North Hertfordshire (Great Offley) (Kings Langley)

3.8 In addition to these localised variations, colour, shape, coursing, technique and conscious ‘borrowing’ of styles helps to create a rich palette of possibilities. The principal challenge is to weave these elements into a design which respects and enhances the dominant and distinctive Chiltern style of flintwork. 18 Chapter 3 : Using lint Today

Survey buildings, extensions or lean-tos, rather than appearing as the main walling material. In some cases, only the boundary walls might be 3.9 For new flintwork, the survey should take constructed of flint. account of the following local factors:

3.12 Where flint is considered desirable, it will l Immediate built environment – has flint been then be necessary to assess all the practical extensively used in the area? factors - availability of materials and skills, l Historical development of the site and timescales, costs etc. – to determine whether it is surroundings – is there evidence for flint feasible to do so. Sourcing suitable flints may being used on or near the site in the past? require a considerable lead time. l Geological – what types of flint are Flint may be inappropriate in developments designed available? What types of materials can flint with a suburban character be combined with? l Local techniques – what are the local forms of flintwork?

3.10 Decide whether flint would fit into the context of the project. In some circumstances, flint might be rejected as an unsuitable choice. For Flint extensions were often added to earlier buildings example, flint may not be appropriate for cul-de- (Binfield Heath) sac or suburban developments. However, these forms of development will invariably be inappropriate in the AONB. On the other hand, it may be particularly well-suited to one-off building projects, terraces or small clusters of buildings.

3.11 Decide the extent to which flint is appropriate to the scale and nature of the project; will it be the major material or is it best suited to discrete Suburban details look out of place elements? Flint was often used on secondary in a rural setting Chapter 3 : Using lint Today 19

these areas. Alternatively, a local estate might Survey Checklist have exerted a considerable influence on the local style of building, which should be l Do use flint in new designwork to a high respected in new design work. specification l Do respect historic diversity in flintwork 3.15 A thorough survey of this nature will lead l Do research the availability of local to a high quality specification, ensuring that the sources of flint type of construction and mortar specification is l Do research techniques and styles in the appropriate and blends well with existing immediate area and so avoid producing flintwork in the vicinity. work that has no regard to local precedent Estate Lodge,1844, probably by Pugin (Danesfield) l Do consider replacing inappropriate boundary fencing with brick and flint walls

Locally sourced materials bricks, tiles and flints 3.13 If any consolidation to existing flintwork is ( Heath) l Don’t needlessly destroy historic fabric required, the survey should identify the areas to be repaired and the most appropriate methods to ensure they are carried out with due regard to surviving historic fabric.

3.14 A close inspection of flintwork in existing buildings around a proposed development might well reveal subtle local characteristics that can be incorporated into new building work. For example, proximity to chalk will tend to produce unstained, unadulterated black and white flints; as these are easier to knap, more examples of knapped construction are found in 20 Chapter 3 : Using lint Today

Specification and Design Figure 2 ii. as solid ; if used structurally it

Knapped flints in lime should be 1.33 times the thickness of a brick/ Building with flint mortar block wall (Building Regulations: Approved Stainless steel wire ties or 100mm concrete mesh to suit flint course Document to PART A). The U-value of a block plastered 3.16 Masonry walls are traditionally made with 100mm concrete block solid 450mm flint wall with no insulation is 2.7 2 building blocks bonded together with a jointing DPC W/m K, whereas a value of 0.35 is looked for material or mortar. With flintwork, the proportion Brick plinths in local in walls to heated buildings (see v. & vi.) facings of stone used is sometimes less than 50% given Ground level iii. as solid masonry in non-structural situations, the amount of mortar, rubble and other stone or a free-standing flint wall 230mm (9") wide can brick used in the finished construction. be built to a height of some 1.5m (5 ft) – any Section through cavity external wall (dwelling) (cavity ties not shown) higher will require a width of 330mm (13") 3.17 The thickness of a flint wall will vary in (brick and a half or maybe more). accordance with the size of structure; traditionally Figure 3 iv. as above but with a rubble or blockwork core Knapped flints in lime the minimum normal thickness for cottage walls mortar – used for constructing free-standing walls.

would have been about 450 mm (18 in) and even Plasterboard and Stainless steel wire ties or (Fig. 1) thermal insulation mesh to suit flint course boundary walls were seldom much less. Some laminated boards v. as a facing to an outer skin in a cavity wall. In on metal studs church tower walls are as much as 1.5 m (5ft) thick. 140mm lightweight habitable buildings, the perceived limitations concrete block to using flint in a cavity wall result in token DPC panels of flint being incorporated into a brick Figure 1 Brick plinths in local facings outer skin. But it is perfectly possible to Ground level construct buildings to a high specification, Special clay capping Section through solid external wall (dwelling) meeting the required thermal values, using Brick dressing to detail (cavity ties not shown) cavity walls with an inner skin of brick or

Dense concrete blocks blockwork or shuttered concrete and an outer min 100mm thick 3.18 Flint can be used in at least eight different leaf of flint on a usually 100mm (4") brick or Knapped flints in lime ways: block backing. This necessarily creates a mortar slightly thicker wall than the conventional Stainless steel ties min 450 centres i. used for foundations for boundary walls and 340mm (13½"), with inevitable cost small outbuildings, instead of concrete implications. However, as walls account for Section through solid wall with half-round coping Chapter 3 : Using lint Today 21

less than 10-15% of new-build, the additional quoins and sometimes horizontal brick string beyond the general line of the wall face. Profiles cost is negligible. (Fig. 2) courses to bind the flint face to the backing should be used for quoins and jambs. vi. as a non-structural facing to some other material or core of the wall. Metal wall ties are also backing material such as brick, block or often used. Shuttered flintwork shuttered concrete. (Fig. 3) vii. flint cobbles or knapped flints can be used for Freehand flintwork 3.21 Shuttering has long been used for flooring and pathways constructing flint walls, both for rubble-cored viii. as a decorative motif mixed with other walls and flint facings on brick or stone backings; materials such as brick or stone (e.g. knapped it can help to achieve flat planes although it is flints can be used to create pinnacles for obviously difficult to gauge the finished effect. parapets or gate piers.) At an early stage in the design process contact should be made with the local Building Control Service for advice on building regulations, required u-values and structural support. Constructing flint freehand

3.20 Flintwork can be constructed freehand or using shuttering. Freehand construction should be the favoured method wherever possible as it Shuttered flintwork tends to achieve a better finish; it is essential when building coursed or rough-coursed 3.22 Before erecting shuttering, any toothed flintwork, where the flints are laid in horizontal quoins or piers, dressings, plinths and backings rows with consistent spacing between each piece. should be built to a minimum height of 225mm (i.e. String lines are used on both sides if constructing the average height of a board laid horizontally). a free-standing wall. The principal technique is to Layers of flint are added within the shuttering Knapped flints mixed with cobbles and setts learn how to bed the flints ‘flat’, as if the wall was made of boards firmly secured on either one or 3.19 For facing or structural work, combination being built against a sheet of glass, using a both sides of the wall. Selecting the flints primarily materials will be used for piers at intervals, end straight edge to check that nothing projects for their external face, they are laid like headers 22 Chapter 3 : Using lint Today

with one end set firmly against the shutter and the Construction Checklist other pointing into the wall; also slightly downwards and outwards to direct any water l Do specify flint rather than concrete for away from the core of the wall. foundation work for boundary walls and outbuildings 3.23 When bedded comfortably in the mortar no l Do ensure cappings properly protect two stones touch, but should be set as close flintwork together as possible to avoid excessive areas of l Do specify use of large flints at the base of mortar. Long bonding flints should be built in at a ‘rise’, and use small flints to level off at regular intervals, with any voids being filled with the top brick and tile rubble, but care is needed to ensure l Do specify use of traditional and locally that every crevice is filled, especially in the The token panels of flint do nothing to enhance the distinctive methods of design and toothing of the piers. Smaller flints will be required appearance of this poorly designed building construction to level off each rise to avoid excessive l Do use flints from the Chilterns thicknesses of mortar which distort the overall a random effect, thus avoiding a banded appearance and are vulnerable to frost. This gives appearance which is not typical of the Chilterns. l Don’t specify random token panels of flint Shuttering to each rise is normally as a design feature in otherwise brick- removed the following day; the walled buildings process being repeated until the l Don’t use imported flints of inappropriate required height is achieved. size and texture

Imported flints change the visual character of buildings

Even with careful pointing the appearance of the banding effect of manufactured blocks is difficult to disguise Chapter 3 : Using lint Today 23

Designing with lint Choice of individual flints - knapped, whole, random or mixed Type of flint 3.26 Flints were either used whole, fractured or 3.24 Good quality work uses chalk flints, although ‘knapped’ to provide a shaped, smooth surface. where they are predominant, the effect can be Knapped flints can be split so ‘over-busy’. Field flints tended to be used in that irregular but ‘flat’ faces are ‘humble’ domestic buildings, boundary walls etc. exposed. Flint often breaks in Pleasing results can be achieved by mixing the handling, sometimes in a two types of flints. remarkably sheer plane, causing it to resemble a ‘knapped’ surface. A skilled knapper can split flint with very little force, Field flints being able to judge its condition and quality by the sound of the blow. Chalk flints are more workable – three strikes will Flint : before (above) & after produce a good face, while field flints often only allow one hit before they Chalk flints fracture. Chiltern walls often 3.25 Flint walls can be smooth textured, rough incorporate whole, faced, or knapped into precise blocks. Ways of random and laying flint are nearly as varied as the material ‘fractured’ flints. Mixed field and chalk flints itself. Different methods of coursing, close or wide In some cases, one spacing and the consistency and appearance of area of wall may the mortar all contribute to this diversity. Other limitless ways, from the wholly random to the use knapped flints, materials can be combined with flint in almost methodically planned. another random. 24 Chapter 3 : Using lint Today

Interesting combination of rinded chalk and knapped Type of finish – squared/graded/random flints

3.27 Flints can be selected and graded on size, they can be used randomly, or can be made into squared or rectangular flint blocks (usually measuring about Squared and knapped flint 100mm (4") by 75mm (3")).

Left: Centre: Right: whole flints random flints knapped flint

Front wall of knapped flints, side wall of random unknapped flints Use of large knapped flints

Use of small knapped flints

Flints graded by type, size and finish Random finish Chapter 3 : Using lint Today 25

Curved walls

3.30 Where appropriate, the sometimes harsh effect of massed flint can be softened by rounding edges or building in curved designs.

Coursed knapped flint Coursed unknapped flint

Coursed or uncoursed Banding

3.28 Whether knapped or not, flints can be built 3.29 By mixing types of flintwork, or flint with Curved flint walling coursed or uncoursed. Further visual effects can other materials, banded visual effects can be be achieved by laying each piece at an angle or created. slant; when alternated course by course, a Recessed/expressed panels herringbone effect is produced. 3.31 Wall surfaces can be broken up by recessing or expressing Herringbone flintwork panels.

Use of recessed and Banded flintwork expressed panels 26 Chapter 3 : Using lint Today

Design and the Choice of 3.34 Traditional Design Checklist Mortar mortars are made with sand and lime, l Do specify a type, size and finish for the 3.32 Building in flint is a slow process. The large the lime being made flint which is appropriate to the scale of quantities of mortar required must be allowed to by burning the design dry out slowly to achieve a firm set. Around limestone or chalk. l Do consider using combinations of 600mm in height is the maximum rise under typical Whereas most smooth, fractured and knapped flints to conditions. Winter working is inadvisable and will modern buildings achieve variety in texture limit the work. are made with l Do employ techniques which help to mortars using soften the effect of massed flint walling Portland Cement, l Do use random, field flints on ‘vernacular’ the elasticity and buildings porosity of lime Impressive use of flint marred by poorly executed mortaring l Do use knapped chalk flints for mortar allows a flint higher status buildings wall to breathe, l Do use other quoin materials - imported moisture to evaporate and fine cracks to ‘heal’. stone, tiles etc – on higher status Its use is ecologically friendly, and even allows buildings the wall to be dismantled and reconstructed in the future without loss of material. l Don’t over-embellish flintwork with

Flintwork cluttered unnecessary detail 3.35 To obtain the best Knapped flint with Wall under construction using lime mortar gritty lime mortar with detail performance from lime mixes 3.33 As flint is such a hard, impervious material, it is essential that the water absorption from mortar is minimal. A strong correct sand and lime to cement based mortar is therefore quite water ratios are used. Sharp inappropriate; shrinkage cracking around the flints sands with angular particles will allow water ingress, with possible damage to including some 4-5mm grit the mortar core or backing, particularly in frosty produce the strongest conditions. The flints themselves can even split in mixes. A less coarse extreme conditions. aggregate may be needed Chapter 3 : Using lint Today 27

for the finer joints of brick quoins, but the colour will be needed to keep it protected from frost in and texture should not be noticeably different. the winter - even heated blankets may be required The choice of binder is essential. A range of limes in extremely cold conditions. As lime mortars will is available; choice will depend on the strength, not set at low temperatures, and frost can cause porosity, durability and flexibility required. A severe damage to work that has not completely generally recommended mix is 1 part moderately cured, it is advisable to plan to carry out new hydraulic lime (NHL 3.5) to 2½ parts well-graded flintwork when there is not a serious risk of frost. sharp sand. In more exposed areas (e.g. on Where shuttering has been used, it should be copings) a stronger mix (1:2) may be required. For removed to allow the mortar to dry after one or conservation repairs, it is recommended that two days. advice is sought from producers of specialist Loose open-bonded joints accentuate the mortar mortars. 3.38 The first layer of excess mortar is removed using a trowel. On no account should cloth or Close or open-bonded 3.36 The mix should aim to completely integrate sacking be used as it will smear the face of the the sand and lime and contain as little water as flint. One of the arts of flintwork is knowing the 3.40 Flints can be set very close together, or in a possible, sufficient to make it workable, as a stiff correct time to complete the finished joint effect more random, open fashion. mix will be less prone to shrinkage, particularly for required. When the initial set has taken place, the Close-bonded flintwork Unknapped flints require more pointing. The mortar should be mixed in face may be finished with a stiff-bristled brush to mortar than knapped flints. In accordance with the manufacturer’s technical reveal the aggregate in the mortar. The wall should flushwork, which has to be literature. not be brushed so much as beaten, banging the constructed freehand, the surface with the tips of the bristles. A churn brush moisture content of the mortar 3.37 If porous, the backing should be thoroughly is the traditional tool although nylon brushes can should be increased due to moistened and then allowed to dry just enough to sometimes be as effective. A churn brush may the narrow joints, to allow the give the initial suction. The new work should be also be used to remove traces of mortar from mix to be rubbed into the protected from sudden drying by wind or warmth . joints. As soon as the in the summer or frost in the winter, and from rain pointing starts to set, excess at any time. Polythene sheeting or damp hessian 3.39 When specifying flintwork, the following mortar is removed from the (which can be sprayed if it starts to dry out too design considerations for mortar should be taken flints with a small trowel. quickly) should be hung just clear of the wall. into account. Conversely dry hessian and insulation/tarpaulins 28 Chapter 3 : Using lint Today

Mix – aggregate, lime putty Jointing and finish sharp sand/coarse aggregate and small lumps of unburnt lime or chalk often exposed on the 3.41 Aggregates and lime mortar mixes should be 3.43 Various techniques can be used to change surface. This can be achieved by rubbing over the carefully selected. Test panels help to arrive at the the finished appearance of the mortar, although joint with a stick or by stippling (not dragging) a desired effect, and can assist in agreeing the jointing should never be the dominant factor in coarse brush onto the hardening surface. intended finish with planners, conservation flintwork. Flat steel trowel jointing, weather struck officers and building control officers. pointing, beak pointing, raised strap pointing and other modern finishes exaggerate the joint and distract attention from the flint itself. In most Galleting situations the joint or pointing should be consistently flush or slightly recessed behind the 3.42 The waste flakes, pushed into the mortar front face of the flint. joints are called gallets, a technique only very occasionally encountered in the Chilterns. 3.44 In walls using random field flints a rough joint can be found ‘buttered’ or spread (but not smeared) over the edge of the flint. Sometimes it is difficult to establish if this was an original Good mortar finish technique, as the feathered edges to these ‘buttered’ joints tend to fall away over time, revealing more of the flint face – which may now appear rather more pleasing than the ‘workmanlike’ Galletting is seldom encountered in Chilterns. This rare example at Wycombe Abbey shows flint gallets original. The surface pressed into the mortar of a masonary wall texture of the joint or pointing was always Ribbon pointing swamping fairly rough with original flintwork Poor mortar finish Chapter 3 : Using lint Today 29

Mortar Checklist Material Combinations window and door openings. The presence of good brick earth means that flint, in the absence 3.45 Because flint is somewhat intractable, ‘softer’ of other good building stones, is often combined l Do point so that the joint is very slightly or more workable materials are usually used in with brick, both in the walls of older buildings recessed behind the front face of the flint conjunction with flint for cappings, piers, quoins, and in boundary walls around estates, l Do consider using appropriately textured banding (horizontal and vertical), string courses, farmsteads and gardens. The clay is also used to mortars make clay peg-tiles, the most common roof l Do use appropriate lime mortars covering of vernacular buildings in the Chilterns. The use of brick, flint and tiles provide a direct l Don’t clutter or obscure flintwork with link between the special character of the region’s inappropriate pointing landscape and the distinctive quality of its Brick and flint column l Don’t use soft yellow ‘builder’s sand’ or traditional built environment. inappropriate aggregates for mortars l Don’t use acid washes to eat back mortar 3.46 A particular choice of combination materials on shuttered walls is often dictated by local geological conditions. l Don’t use flat steel trowel jointing, weather Brick textures vary according to the type of clay struck pointing, beak pointing or raised used. Proximity to certain quarries produce strap pointing pockets of localised use of stones.

Brick

3.47 Chiltern brickyards produce bricks in colours ranging from orange through brown and red to rich purple, almost to blue. Newly-burnt bricks need to be soaked in water before use because of their absorbency – otherwise the mortar would dry and lose its adhesion.

Brick and flint combination 30 Chapter 3 : Using lint Today

3.48 Brick is sometimes mixed Stone randomly into flintwork. More elaborate patterns (‘diaper work’) were 3.51 The alternative produced in imposing buildings, mixing to clay was dressed knapped flint with dressed brick. stone, but because of its cost it was 3.49 Imported bricks such as yellow Diaper work sparingly used and ‘stocks’ are encountered in the is more often Chilterns, changing the overall texture Tile associated with and appearance when incorporated in prestigious Composite stone, brick and flint flint buildings. 3.50 As clay tiles were locally produced in a buildings such as number of areas – it is no surprise to find them churches or estate being used for quoins and lacing courses as at buildings. In the Chilterns it has mainly been derived either from quarries at Totternhoe or at Random brick in flintwork Penn. Denner Hill. Other limestones and had Yellow brick and flint Tiles used in flint and stone buttress to be imported into the region. On superior buildings, stone is combined in formal diaper and chequerboard patterns to great decorative effect. Stone, tiles and bricks can sometimes appear randomly used in flintwork.

Denner Hill stone quoins Chapter 3 : Using lint Today 31

Thatch in a rusticated form being used for the 3.52 Thatch was once much more common on quoins in an humble buildings such as cart sheds and lean-tos, otherwise brick although few examples survive today in the building). Corner Chilterns. Thatch-and-flint domestic buildings are quoins are often particularly encountered in the scarp areas, close three courses high to the arable Vale of Aylesbury. though it is not uncommon to see them four, five or more courses high. Slate Flint and thatch In the Chilterns, Traditional three course quoin 3.53 While many flint buildings are roofed with Design details however, quoins or peg-tiles, slate has been used since the C19th as piers often present a toothed appearance, “in” and at Lane End, , Lee Common or Stoke 3.54 Although it is perfectly possible to use flints “out” on successive courses. Row. for any of the following design elements, local Slate and flint examples will help to provide clues as to the most Typical Chilterns ‘toothed’ quoins appropriate combinations. These details are intended to show the range of combinations available, but they should not be applied indiscriminately. The successful design will incorporate them in proportion. Flints used as quoins

Quoins and piers

3.55 Although examples occur, it is difficult to make good, strong corners with natural flint. Brick or stone are more frequently encountered. (In one or two cases, the reverse occurs, with flint, usually 32 Chapter 3 : Using lint Today

Arches, door and window openings Strings/lacing courses

3.56 Dressings to the jambs of doorways and 3.57 Very pleasing effects have windows often repeat the patterns encountered on been created where the flintwork the corner quoins except that their face widths are is divided up into panels by usually less, often consisting of one brick and half vertical and horizontal brick a brick. Window heads develop towards shallow banding. Strings can be done as segmental heads. all headers, alternate headers and stretchers, or random. One

Plain panelled doors Recessed arched course is sometimes quite doorway sufficient, although up to four or Flush brick panels Window with label mould five bricks deep occur in and three-course brick domestic situations at first floor quoining level to accommodate joists; these can be enriched with cogged or dog-tooth detailing or other decorative friezes, but keeping the correct visual ratio of brick and flint. The bare minimum of brickwork almost never looks wrong. Too Segmental heads to sash and casement windows much brickwork usually does.

Openings without differentiated quoins Fanlight Single string course Chapter 3 : Using lint Today 33

Copings and cappings

Multiple strings and courses

Eaves

3.58 Because flint is a robust material, eaves do Highly elaborate Plain flint coping Brick-on-edge capping not require a pronounced overhang. Eaves can boundary wall be matched to any detailing carried out at first 3.59 Local brickyards provide a variety of are much used. Brick on edge cappings became th floor level. handmade special coping bricks for cappings - common in the C20 and require 2 or 3 brick Flint and stone buttress apex, half-round, ogee, double bullnose. A 330mm courses below the top course as Cogged eaves and plat band (13in.) wall for instance might top out with a extra protection. course of brick, a course of plinth bricks and a coping brick. However, many variations can be found. Buttresses In the Chilterns half round bricks often associated with splayed plinth bricks and purpose made 3.60 Flint buttresses occur but curved or angled top coping bricks or tile creasing more usually they are of brick or dressed stone, sometimes Typical half-round capping incorporating small panels of flint. 34 Chapter 3 : Using lint Today

Designing with Existing lint Material Combinations Checklist 3.61 Extensions and conversions will involve disturbing historic flintwork. When refurbishing a l Do combine flint with other appropriate property, repairs may well need to be carried out. Chiltern materials, keeping the With new build, long-term maintenance needs relationships between ratios, massing and should be borne in mind when the design brief is openings in fine balance being prepared. l Do use traditional Chiltern bricks at the Extensions should be carefully blended into base and top of walls, and for existing flintwork intermediate bands. Incorporating some yellow stocks can also create an interesting effect 3.62 Prevention is better than cure and good l Do consider using lacing tile courses for decorative effect maintenance will extend the life of a flint wall by: l Do experiment with decorative patterning l Do use matching bricks for extensions and alterations l Keeping walls clear of ivy (which will eat into the mortar and expose the soft inner l Do use brick for piers and quoin details core of mortar and rubble) and disturbance l Do experiment with thatch for Damaged and vandalised flint shelter (above) outbuildings or extensions with a new lease of life (below) of foundations from tree growth l Repairing defective roof coverings and l Do consider using other walling materials for one elevation of a predominantly flint keeping rainwater down pipes and gutters building unblocked l Monitoring (or improving) site drainage to avoid rising damp l Don’t use inappropriate capping, quoin, pier or lacing materials l Regularly maintaining copings

Where remedial work has become essential, advice should be sought from suitably qualified specialists. Chapter 3 : Using lint Today 35

3.63 Old flint walls often brick or stone may wear back first. The failure of have shallow or non- the water-shedding coping of a flint boundary wall existent foundations, will lead to the rapid washing out of the mortar ground movement will core by driving wind and rain resulting in cause them to lean or inevitable collapse. crack. Roof thrust can create similar problems. Facing flintwork may become detached from its brick or stone backing. Poor bonding can also lead to rubble-cored flint walls becoming weak and Even sensitively executed repairs change the appear- unstable, or to joints with Flint in poor repair ance of flintwork dressings and cappings opening up. Flints may behind the flint facing), or have ‘popped’ due to have split or become dislodged due to unequal moisture penetration and build-up through hairline settlement or overloading, mortar erosion (in and cracks in cement-rich mortars. Dressings of softer

Deteriorating softer dressings

Failed chequerwork Cracking in hard cement mortar 36 Chapter 3 : Using lint Today

3.64 Bulging or leaning walls, open joints and Figure 5 Repairing flintwork with lime mortar widespread cracking should all be referred to a Reattachment of poorly bonded brick dressing suitably experienced structural engineer. It is Stainless steel brick advisable to monitor the situation for six months reinforcing mesh or a year to establish whether the movement is historic or live. If the former, voids in rubble cores or cracks in the facing material may be filled with liquid mortar and ties and stitching may arrest the problem where facings or dressings have failed without recourse to major re-building.

Figure 6 Mesh secured this end with Face rebuilding Figure 4 plugs, screws and washers Fracture repair Stainless steel brick reinforcing mesh Brick backing Stainless steel brick secured to reinforcing mesh brickwork built into core with plugs, screws and washers

Brickwork

Additional stainless steel brick Fracture reinforcing mesh laid horizontally and bound with wire Chapter 3 : Using lint Today 37

3.65 flint and brick walls and the 3.67 Where black or coloured mortars have been copings should be considered on structural need used, such detail should be reproduced wherever rather than appearance. A great deal of repair and possible, although impurities such as salts and repointing is poorly executed with mortar smeared clay in the additives can be harmful. crudely over the faces of the flints, using an incorrect cement rich mortar. Even good repointing 3.68 Close reference should be made to the will upset the visual balance of a previously well- existing historic finishes – look for unweathered weathered flint wall. In any repointing or repair of jointing in protected areas of walls, such as knapped flint walls it is essential that the flint under wide eaves or in hidden corners or in faces are cleaned thoroughly as work progresses. recesses behind buttresses or piers.

3.66 As close a match, in texture and composition 3.69 Where rebuilding is necessary, particular as possible to the existing historic mortar present attention should be given to the selection of in the flint walling should be sought. This may matching flints, their pattern and spacing and include some quite large sized aggregate – almost marrying together the new and the existing work. small gravel and small unburnt lime chunks or chalk. Some of this mortar may be re-usable, if mixed with more lime. As the mortar needs to provide a good bond to the flints and to the old Repair Checklist backing mortar, matching existing mortars as closely as possible will help to reduce shrinkage l Do seek specialist advice for repairing cracks and will match permeability to avoid flintwork trapping moisture. Sample panels (small areas of repair carried out in advance of the main work, to l Don’t spoil existing flintwork with demonstrate that the workmanship and materials unsympathetic repairs match the originals) should be used wherever l Don’t use hard cement for repairwork possible. For suitable mixes, see SPAB Technical Pamphlet 16, 2000. pp.6-7. 38 Chilterns lint

Glossary Flushwork: Technique of setting knapped flints Patination: A wax-like sheen on some corticated flush with the face of dressed stone. Used to form flint, due to later assimilation of silica decorative compositions in superior work Ashlar: Squared freestone masonry wrought to Plinth: Projecting base course to a wall, buttress or even faces Fractured flint: A flint broken naturally or one pier etc. crudely severed to reduce it to a more convenient Beak pointing: Mortar raised to a V-point size. Used in walls with whole flints Polychromy: Decorative schemes in several colours Chequerwork: a pattern, usually of squares, of Gallets: Flint chips set in wide mortar joints for two materials, e.g. flint and stone, arranged in a decorative effect Quoins: Corner stones or bricks forming the chessboard pattern external angles of a building Header: the short end of a brick seen in the face of Cobble: water-rounded flint or other stone between a wall Rendering: A cement or plaster coating to the 75mm and 300mm in diameter surface of a wall Hoodmould: Moulding in stone or brick over an Core: The inner body of a piece of flint. It usually arch or lintel to throw off water Rustication: Accentuation of masonry to create appears black when freshly fractured shadows using chamfers or square sinkings round Hydraulic lime: Lime prepared from an impure the face edges of individual stones, emphasized Course: A continuous horizontal layer of bricks, limestone. At least part of its setting action could joints or extravagant surface textures stones or flints, etc. in a wall take place under water Split flint: General term for fractured or knapped Cortex: The white rind of a flint Jambs: The straight sides of a doorway or window flint opening Derived flint: Flint freed from its original chalk Stretcher: The long side of a brick seen in the face matrix and found in fields Knapped flint: Flint that has been deliberately of a wall struck to present an approximately flush face for Diaper: A pattern repeated as a criss-cross of aesthetic purposes. For superior work, they are String Course: A projecting course or moulding of diagonal ‘lines’ in one material, usually brick trimmed to regular shapes stone or brick running horizontally along the face headers, to define a lattice of diamonds or lozenges of a wall in another material Lacing course: Horizontal, intermittent bands of bricks or tiles used to level up and tie the front and Virgin or raw flint: Flint obtained directly from the Dressings: Stonework or brickwork forming the back of a wall together without the use of modern Upper and Middle divisions of the Chalk formation quoins of a building, or the jambs and heads of metal wall ties (cf. derived flint) doorway and window openings etc. Nodular flint: Flint formed as small rounded lumps, Weather-struck pointing: Mortar sloping inwards typically measuring between 50 and 125mm from the bed joints to cast off the rain Chilterns lint 39

Bibliography urther Advice

Amsden, T., Brick & Flint Building, Period Home, Mason, H.J., Flint, The Versatile Stone, 1978 For any new development proposal you should March 1987 initially contact a Development Control Planning Parissien, S., ‘Stonework’ Guide No. 12, The Officer in the Planning Department at your local Ashurst, J & N., Practical Building Conservation, Georgian Group council. Additionally, if your proposal involves a English Heritage Technical Handbook, Vol. 3, listed building or is in a Conservation Area, you ‘Mortars, Plasters & Renders’, 1988 Shepherd, W., Flint, Its Origin, Properties & Uses, should contact a Conservation/Listed Buildings 1972 Officer. You may also need to contact your Local Barber, M., Field D. & Topping P., The Neolithic Building Control Service. Flint Mines of England, English Heritage/RCHME, 1999 Details of all the councils that cover the Chilterns Chilterns Conference, Chilterns Buildings Design AONB can be found at the Chilterns AONB Guide, A Countryside Design Summary, 1999 website: www.chilternsaonb.org

Clifton-Taylor, A. & Ireson A.S., English Stone The website will also contain details of suppliers, Building, 1994 edn. practitioners and other useful contacts. This list may change from time to time, so it is Dawson, B., Flint Buildings in West , recommended that you check it regularly if you Planning Department, West Sussex County undertake projects at different times. Council, 1998

Forrest, A.J., Masters of Flint, 1983 For further information and advice contact the Chilterns Conservation Board at the following Goodwin, C., Flint, Norfolk Museums Service address: Information Sheet, 1983 Chilterns AONB Office Hart, S., Flint Architecture of East Anglia, 2000 8 Summerleys Road Hepple, L., & Doggett, A., The Chilterns, 1992 Bucks. HP27 9DT

Hydraulic Lias Limes Limited, ‘Blue Lias Hydraulic Tel: 01844 271300 Lime: best practice instructions for general Email: [email protected] masonry, render & plaster,’ 2002 Fax: 01844 271301 Lodge, D., and Wright, A., Care and Repair of Flint Walls, SPAB Technical Pamphlet 16, 2000 Published with assistance from

WYCOMBE DISTRICT COUNCIL

ISBN 954524209-4

ISBN0- 9545242- 0-9545242-0-9 0- 9

an Area of Outstanding Natural Beauty