Construction Using Local Materials

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A project of Volunteers in AsiaConst r uct i on Ref erence Manual- -by Donal d Bat chel der et . al .

Publ i shed by:The Exper i ment i n I nt er nat i onal Li vi ngKi pl i ng RoadBr att l eboro Vermont 05301USA

Avai l abl e f r omsame as above

Repr oduced by perm ssi on.

Repr oduct i on of t hi s m cr of i che document in anyf or m i s subj ect t o t he same r est r i ct i ons as t hoseof t he ori gi nal document


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Ib'1 1

ocal aterialsnstruction

EXPERIMENT IN

BATCHELDER ROBERT E. CAIOLA STANTON W. DAVENPORT


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A Sourcebook For The Use Ofaterials In Construction


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Copyright @ 1985by The Experiment in International LivingKipling RoadBrattleboro, Vermont, 05301U.S.A.

Grant assistance was provided by the Australian High Commission,Nairobi, Kenya; the Canadian High Commission, Nairobi; andCatholic Relief Services.

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A Sourcebook FOPThe Use OfLocal Materials In ConstructionTRE KITEREDDE CONSTRUCTION INSTITUTE

andTHE EXPERIXRNT IN INTERNATIONAL LIVING

KITEREDDE, UGANDA

DONALD BATCBELDER, ROBERT E. CAIOLA, STANTON W. DAVENPORT

THE EXPERIMENT PRESS

1985


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T BLE OF CONTENTS

INTRODUGTION. .~................*....................*.............. 1

-RI LOCAL BUILDING MATERIALS . .e...*......... 4Mud Bricks .................................................. 5Raw Materials............................................... 5Clay for Brick-Making ................................... 6Testing of Clays......................................... 7Clays in Southern Uganda ................................. 8Digging Clay for Brick-Making............................ 9Processing the Clay ...................................... 10Bricks ..................................................... 10Brick Size-.............................................. 10Moulds ................................................... 11Calculating Brick Quantities............................. 12Table Method of Hand-Moulding Bricks and Blocks.......... 12Drying and Stacking Bricks and Blocks .................... 14Burning of Bricks in a Country Kiln......................... 15Large Country Kilns ...................................... 15Small Country Kilns ...................................... 15Kiln Construction ....................................... 17Kiln Operation ........................................... 18Kiln Fuels............................................... 20Selection and Identification of Wood and its Usage.......... 20Wood for Special Purposes................................ 21Timber Species Most Commonly Used in Uganda .............. 21Softwood Identification ................................. 21Hardwood Identification ................................. 21Wood 'Treatment.......................................... 22Drying and Stacking Wood................................. 22

(ZHAPTER 1 BASIC BUILDING COMPONENTS. 25Introduction .I..................................*.......... 25Foundations ................................................ 25Laying Out a Foundation .................................. 27Concrete Perimeter Foundation ............................ 28Excavating, Pouring, Forms.................................. 29Pouring Concrete......................................... 30Concrete Slab Floors..................................... 31Cast in Place Concrete Piers ............................. 32Wo.od oles............................................... 33

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BASIC BULIDING COMPONENTS (continued)Types of Walls ............................................... 34Mud or Adobe Brick........................................ 34Mud Block................................................. 35Burned Bricks............................................. 35Concrete Block............................................ 35Stone Walls............................................... 36

Corrugated Iron........................................... 36Veneer Walls .............................................. 36Fise or Rammed Earth...................................... 36Common Mud Walls.......................................... 36Thickness and Height of Walls and Gables.................. 37Bricklaying: Solid Walls and Joints in Brickwork.......... I. 39Importance of Mortar...................................... 39Meaning of Brickwork ..................................... 39Size of Mortar Joints .................................... 39Bond in Brick............................................. 40Types of Bond in Brickwork ............................... 40

Terms Used in Bonding .................................... 41Roof Framing................................................. 42Instructions for Building a Gable Roof .................... 42Eaves ..................................................... 44Flat Roof................................................. 44Roof Trusses.............................................. 45Roofing Materials......................................... 46Windows and Doors. .*.........*.....................*...... 48

CEAPTER III ALTERNATIVE BUILDING MATERIALS AND TECHNIQUES............. 53Introduction .*......*....*................................ 53Local Material Mixes......................................... 54Concrete Foundation Using Local Materials................. 54Mortar Cement............................................. 54Damp-Proof Course......................................... 54Foundation Mortar......................................... 54Interior Plastering....................................... 54Exterior Plastering ...................................... 54Concrete for Ring-Beam ................................... 55

Concrete for Floors....................................... 55Mixing Alternative Cements................................ 57Anthill Kiln and Anthill Clays. .*....................a..... 57Locally Available Paints and Paint Colours................... 60Local Paint Brush. 61

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CHAPTER IV BASIC MATHEMATTCS FOR CONSTRUCTION........x.............. 63Fundamental Ideas in Geometry.............................. 63Formulas and Examples................................... 64Summary of Formulas ..................................... 67Concrete Mixes and Calculation of Cubic Yardage............ 68Calculating Strength for Wooden Beams....................... 70Symbols and Abbreviations..,..*............................ 74Useful Numbers.............................................. 74Weights................................................. 74Weights of Substances .................................. 75Linear Measurement ..................................... 75Area Measurement........................................ 75

CHAPTEXV PLANNING AND MANAGEMENT. 77Introduction .,.....,..........................e........... 77Securing Authority......................................... 77Planning .................................................. 78General Building Calendar............................... 78Policy .................................................... 79Seeking Advice.......................................... 79Selecting a Site. ..*..... 79Business Detail............................................ 80

Orders.................................................. 83Contracts ............................................... 83Accounting.............................................. 84Care of Materials....................................... 84Labour ..................................................... 85Labour Agreements....................................... 86Labour Relations........................................ 86Supervision of Labour................................... 88Calculating Simple Interest. ."..................... 89

CHAPTER VI BASIC SKILLS AND OCCUPATIONAL PROFILES.................. 91Introduction .............................................. 91Occupational Profiles ..................................... 91Performance Standard Key................................... 93Masonry Task Listing....................................... 93Carpentry Task Listing..................................... 97Cabinet-Making Task Listing ................................ 99Drafting Task Listing...................................... 100


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APPENDIX I GLOSSARY. .*...................................... 103

BpPENDIXIIREIrERENcESANDAcRNowLEDGEEIENTS . .*............. 111

ENDLEAF............................................................... 113The Kiteredde Construction Institute......................... 113The Experiment in International Living....................... 113

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INTRODUCTION

Housing and shelter are fundamental needs throughout the world, andeach country and cultural group attempts to meet its own needs by designingstructures which are appropriate to the climate, conditions and materialsavailable. In modern times, the advent of mass production, long-distancetransport and vigorous marketing systems have made possible, in some cases,the importation and movement of housing and building materials from oneregion or continent to another.

In many cases, however, the surplus capital for the purchase of manu-factured products and processed building materials does not exist, and manycountries cannot afford to expend precious foreign exchange on importedcement, steel reinforcing bars, metal roofing sheets and other materialsfor construction, in view of the manv pressing needs in agriculture,health, education, industrial development and other important sectors.At the same time, many of these same countries do not have the rawmaterials, capital or capacity to produce sufficient quantities of buildingmaterials for national needs and at prices which are within the reach ofordinary family budgets,Many excellent sourcebooks and technical manuals have been published onthe subjects of low-cost housing, the use of local materials for buildings,the design and ste?-by-step construction of houses, clinics, schools andpublic and commercial structures, as well as agricultural sheds and storagefacilities. It is not the purpose of this small bock to duplicate the goodwork which has already been done by others, but rather to take a look at aspecific area of the world, and to address actual construction issues fromthe perspective of several years of direct hands-on experience, and perhaps

most important of all, from a slightly different premise,Simply stated, the premise underlying this volume is that a significantgap exists in construction literature, which is that most of the technicalmanuals we have studied assume a certain level of availability of manu-factured materials. The purpose of this manual is to provide a basicunderstanding of the ways in which clean, durable structures can be builtwith local materials and in the total or near-total absence of manufacturedmaterials.Expanding populations require additional housing far beyond the capac-ities of many countries to provide. It is estimated that in some African

countries,, he number of housing units will have to double by the year2000, simply to stay even with the demand. While this may be good news forthe construc.tion ndustry, it places enormous strains on financial re-serves, policy makers and natural resources of a nation. It appears likelythat few developing nations will have the financial strength in the nexttwo decades to enable them to provide adequate housing for their citizens,unless a coordinated effort is made to promote self-help housing con-struction, to learn how to make good use of locally available materials,and to support the technical training of youth and adults in basic buildingtechniques and the practical elements of extracting, adapting and usinglocal materials. The customary system of importing manufactured products


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and processed materials will not solve the problem of providing adequatehousing for the vast numbers who need it now, and for the masses ofchildren currently growing to adulthood who expect to have families andhomes of their own.In 1979, The Experiment in International Living, a private voluntaryorganization, and the Bannakaroli Brothers, an African Catholic order, with

headquarters in Kiteredde, Rakai District, llganda, ointly planned avocationai training center which was specifically designed to train youngmen and adults in construction skills using locally-available materials.The Kiteredde Construction Institute (KCI) was established in 1980.Initial funding support was provided by the Congress of the United States,and administered by the U.S. Agency for International Development (USAID)(1979-81). Additional support was provided by the Canadian InternationalDevelopment Agency (CIDA), the Australian High Commission, Catholic ReliefServices, and The Experiment in International Living. Land, work space andstart-up facilities were provided by the Bannakaroli Brothers.Training specialists from The Experiment worked side-by-side with thetechnical and construction personnel of the Bannakaroli order in all phasesof planning and implementation of the project, from the design of thecurriculum to the actual construction of classrooms, dormitories and workspaces. From the beginning, the emphasis of the program was on practicalskills development, learning by doing, the preparation of trainees for jobsin the construction industry and in public works departments, and theplacement of each in wage-earning employment immediately upon graduation.Were this volume intended to be a history of the Kiteredde ConstructionInstitute, it could include development-related narratives about the phi-losophy of the educational program and its impact upon attitudes towardscraftsmanship, standards and work; it could describe the training of young

men in the elements of small business management, and the subsequent forma-tion of a number of small-business firms by graduates, which are now carry-ing out useful construction projects in Uganda; it could speculate on thepossible socio-economic ramifications of the fact that KC1 has over 500applicants for the 25 spaces in each entering class; it could mention theincreasing volume of requests for KC1 to provide outreach, extension andtraining services for others; it could include a description of the tech-nical assistance KC1 personnel have provided to other development programsin Uganda, such as well construction and basic skills training; or it couldtell about the progress made in opening up new farm acreage to move theinstitution towards self-sufficiency; or could try to explain why employersin public works offices and in the construction industry request more grad-uates to fill jobs than the institution can provide.

But perhaps the single most relevant component of the program whichrequires mention here is the Bannakaroli Brothers' knowledge of the use oflocal materials for construction, their experience in practical applica-tions, and in training others how to use them.


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New construction and the building of new houses came to a virtualstandstill in Uganda in the 1970s. The construction industry lacked mat-erials, and the state of the economy forced people to reach back to allbut forgotten materials and methods.The Bannakaroli Brothers had worked for a number of years with theexcellent clays and other materials available in southern Uganda, and had

employed them in the construction of their own buildings, and in carryingout construction assignments for others. This knowledge of brick, tile,block and clay moulding; of efficient kilns and appropriate firing tech-niques; of masonry and carpentry; of tropical building design; of the useof local materials to make mortar, paints, plasters and other necessaryelements of construction, in the absence of manufactured and imported mat-erials, form the basic components of the training program at the KitereddeConstruction Institute, and the basic contents of this manual.

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c

CHAPTER 1

LOCAL BUILDING MATERIALSIntroduction

There are many problems plaguing the building industries in Africa andin other developing regi.ons, n view of growing populations and demand forhousing. The high custs of importing materials, and of producing high-quality building materials domestically, are perhaps the major constraintsto progress. In addition, local production of building materials in manyareas cannot keep pack with demand, particularly in rural areas where thereis limited access to urban factories and where transportation facilitiesare limited.A practical response to these problems is being carried out in southernUganda through the use of locally available materials. The contents ofthis chapter provide introductory information about the techniques and mat-erials being used by the Kiteredde Construction Institute, local area con-tractors and residents in building affordable houses and other structures.Construction techniques in the area are primarily masonry-based, be-cause of the excellent clays which are readily available. Houses are gen-erally built with light-weight metal roofing (corrugated sheets) and con-ventional aperture treatments, with typical electrical and plumbing in-stallations.Not all problems have been resolved. Work is being done to address thechronic lack of durable, light-weight roofing, made from local materials,which will eliminate the expense of metal roofing. Locally produced cementin Uganda, as in many other countries, is often of poor quality, and lime

as a bonding substitute, or as a supplement to save on the volume and costof cement, is rarely used, despite the availability of lime deposits inmany areas. This is primarily due to the cost of the equipment needed toproduce lime from extraction, and the systems to make it available in localmarkets at reasonable prices.In general, the use of local materials needs to be supported and re-inforced to produce sufficient quantities of materials of adequate qualityto withstand the effects of climatic conditions which range from humidrainy seasons to extremely hot dry seasons. Mud structures, mud and wattlebuildings, and locally produced bricks and blocks do not endure for many ofthese seasons, and must be constantly patched and repaired.A recent socio-economic study of four districts of Uganda offers someinsight into the general condition of housing in representative areas:Kigezi, Masaka, Teso and Busoga. Of 2702 households sctrveyed, 58 weregrass huts (9%); another 900 were round mud-and-wattle construction withthatched roofs (33%); another 740 dwellings were rectangular mud-and-wattleconstruction with thatched roofs (27%); there were 679 houses of mud-and-wattle, rectangular in shape, with iron roofs (25%); and 117 rectangularhouses made of brick and block construction with iron roofs (4%).


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Without going into a detailed analysis of these figures, it is safe tostate that a great volume of sub-standard housing ex'.sr,s n Uganda as else-where, particularly in rural and village areas.In response to the need for better housing at reasonable cost, thischapter offers techniques of clay extraction and preparation; testing forclay plasticity; basic standard brick and block sizes; moulding, drying,stacking and storage of air-dried bricks and blocks; kiln construction;fuels and firing techniques for kilns; wood identification and treatment;and the uses of different kinds cf woods in construction.Clearly, the emphasis on clays, and brick and block construction, inthis chapter is not entirely suitable for builders in regions where clay isnot readily available, but the approach to iderltifying nd making good useof the materials at hand may be useful. Chapter III deals with alternativebuilding materials.Finally, it is hoped that readers will be able to employ the techniquesoutlined in this chapter, or adapt them to their own situations and materi-als, to build more attractive and durable structures, at lower cost, and

with lower repair and maintenance costs over the years. It is also hopedthat over time, contractors and the building industry in general will beginto make better use of local materials to reduce construction costs and tohelp bring clean durable housing within reach of everyone.

LOCAL BUILDING MATERIALSMud Bricks:One of the world's most widely usedbuilding materials is burnt brick.Many countries have deposits of suit-able clay, and good sources of localfuels, so that no foreign exchange isneeded for the production of thisweli-proven building material.Although highly mechanized produc-tion methods are used successfully inmany countries, these may be uneco-nomical where the rate of productionis low, and may be inadvisable wherespare parts, maintenance and serviceare difficult to obtain.Thus in many developing countries,labor intensive production methodsare more appropriate, and if care istaken in production, can produce sat-isfactory bricks.Most bricks made in developing coun-tries are moulded by hand, using tra-ditio'nal techniques which in some in-stances may have been in use for hun-

dreds of years, although machinery isalso employed. Increasingly, localbuilders and markets have indicated aneed to improve the quality of bricksin many areas, and the growing demandfor housing construction has calledfor new production facilities. Themost important areas of improvementin order of priority are:

Improved hand-moulding systems toshape bricks more accurately in areaswhere slop-moulding is traditional;A simple mixing and screening sys-tem for raw materials;The development of a small-scalekiln for firing the bricks.

Raw Materials:The principal raw material used inbrick-making is called clay. Pureclay has a property called plasti-city, which means that it is a mate-

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rial which can be made into a varietyof shapes by applying pressure. Whenthe pressure is removed, the plasticmaterial retains much of its newshape.Dry clay is not plastic. It must befirst mixed with water. When the wetclay has been formed into a specificshape, such as a brick, and then isallowed to drv, it once again b:zcomeshard 316 con-plastic. If, however,the dry brick becomes wet again, theclay becomes soft once more, and run-ning water or rain will graduallywash it away.Rut clay has another important qual-ity. If it is heated until it be-comes red hot, it loses its abilityto become plastic (or to soften andwash away in the rain) when it be-comes wet. It is this last propertythat makes burnt clay bricks so im-portant fo; building houses, grainstores and otiier gricultural struc-tures, drainage ditches, factories,and office, commercial and otherbuildings.Finally, the other most importantproperty of clay is that if it isheated to a high enough temprerature,and then cooled, the strength of thematerial increases until it is muchstronger than the original unburntclay.The clays used in brick-making arenot pure. They vary, not only in thetypes of clays present, but also inthe types and amounts of impuritiesthat are present. The degree of pur-ity, and kinds of impurities, varyfrom one place to another, and alsovary according to the nearness of theclay to the surface or its depth be-low the surface of the ground.The type and amount of clay present,and the type and volume of impuritiesin it, determine whether or not goodquality bricks can be made. Thesefactors, the amount and kind of clay,

and the degree of purity/impurity ofthe sample, determine the kinds ofproblems one may encounter in tryingto manufacture strong durable bricks.Variations in the quality of the claydetermine the proper water mixtures,and affect the moulding and dryingprocess, as well as the proper firingtemperature and kiln-time needed inorder to produce high-quality bricks.Thus, it is most desirable that claysbe tested for suitability and purity,unless reliable testing has alreadybeen done, or unless their propertiesare well known from direct experienceand successful production. It isparticularly important that reliabletesting be carried out regarding boththe quality and quantity of the claysavailable, if someone is planning toestablish a brick-making business, orto invest money in clay extraction orbrick production.Clay For Brick-making:Clay for brick-making must satisfy anumber of requirements:

1. The deposit must be easilyavailable, which means there must beaccess to the deposit so the clay canbe excavated using the facilities athand. At the same time, the clay de-posit should be located within a rea-sonable distance of the people whoare going to buy or use the bricks.

2. The clay must be suitablyplastic when mixed with water, andsuch mixing must be easily done usingthe facilities available.3. The plastic clay must be ableto hold its shape when moulded into abrick? and must not warp, distort orcrack during the drying process.4. The dried brick must be strongenough to withstand whatever handlingis required during the productionprocess. For example, bricks at theground level under the weight of the

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stack of bricks above them in thekiln, must be able to withstand theweight and pressure of the bricks inthe settings above.5. The clay should be free fromharmful impurities such as limestone,large stones and soluble salts. Lime-

stone can cause the brick to burstaround the limestone particles afterit has been fired. Stones can causecracking in the bricks. Soluble saltscan cause harmful and unsightly de-posits on the bricks after they arefired. Limestone particles are usu-ally white to grey in color, and maybe as small as a pin head in size toas large as a groundnut, Largerparticles of limestone can be pickedfrom the clay, if there are not toomany of them, Soluble salts can usu-ally be seen as a fine sugar-like orcrystalline deposit on the clay asit drier..

6. The clay should have the twoqualities of (a> forming into an ad-equately durable brick as a result ofthe firing process, and (b) not dis-torting or warping during firing. Itis important to know that differentclays require different temperaturesfor adequate burning, and that dif-ferent fuels, firing methods, andkilns produce different temperatures.Higher temperatures for hotter firingrequire more fuel, and are thereforemore costly.Wet clay shrinks as it dries, and theshrinkage is in direct proportion tothe amount of water present in theclay. Different types of clay re-quire lesser or greater amounts ofwater to make the clay plastic formoulding , and to produce suitablebricks for firing and use.This quality of shrinkage during thedrying process is important to bearin mind when making a brickmould, orin having one made, because the sizeof the mould must always be slightlylarger than the size of the finalburnt brick, in order to allow for

this shrinkage. A small amount ofshrinkage also takes place during thefiring process.A brick made from a clay mixture withless water is usually more dense andstronger than a brick made from aclay mixture with more water. Duringthe firing process the dense brick,with less water in the clay, has moresurface particles of clay touchingone another, than is the case withwetter clays. These pieces fuse to-gether more readily, and tend to forma stronger burnt brick.Testing To Discover The Amount ofClay In A Soil Sample:1. The Shine Test:

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Take a small handful of soil, and addwater to make a stiff mud. Then mixthoroughly in the palm of your hand.Open your hand and make a flat cakeout of the mixture. Slowly closeyour hand around the cake, and watchthe mixture closely. The cake shouldshine as your hand begins to closeand apply pressure. If not, add morewater and try it again. If the shinedisappears when you open your hand,it means that the soil may have toomuch silt or sand in it. If theshine does not go away when you openyour hand, it should indicate thatyour soil sample contains a high pro-portion of clay. (Figure 1.)

Figure 1


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2. The Worm Test: (Figure 2.1Wet a soil sample until is becomes astiff mud, moist but not watery. Rollthe stiff mud into a worm shape aboutthe thickness of a pencil, and about10 cm long. Use the palm of yourhand to roll out the sample on a flathard surface. Carefully pick up theworm of stiff mud with two fingersholding it at one end. Hold the wormparallel to the ground. If the wormbreaks off from its own weight, itcontains silt and sand. If the wormbends or sags, but does not break, itcontains a good proportion of clay.

Figure 2

Clays irr outhern Uganda:Clays most common in Uganda are RiverBank Clay, Swamp Clay and Ant HillClay.River Bank Clay: (soft clay)

Color: red to whitish to grey.Depth: one to five feet below thesurface, i.e., below grade.Moisture: semi-moist, easilymanipulated or squeezed by hand,this is the most commonly usedclay in the region.Location: it is usually found inlow-lying areas, and generallyaccessible.

Swamp Clay:Color: red to whitish to grey.Depth: one to three feet belowthe surface.Moisture: very moist. Water canbe squeezed out by hand. Duringthe rainy season it is usually notaccessible due to high water tableand flooding. However, if build-ings or wattle houses are beingconstructed near the river or wetarea, this clay can be used tospread on the walls.

Ant-hill Clay:Color: brown to reddish.Depth: Depending on the size ofthe ant-hill, clay can be up toten feet about the ground surface,and down to ten feet below groundlevel.Moisture: very dry.

Using ant-hill clay can serve severalpurposes:1. The clay extracted from theant-hill can be made into excellentbricks and blocks, and also into roofand floor tiles.2. The ant-hill from which theclay is extracted can be dug furtherand shaped into use for a kiln; i.e.,the extracted clay can be mouldedinto bricks and put back into thethree-sided opening and burned.3. No transportation costs frommoulding site to kiln.4. The ant-hill kiln, with threewell closed sides, will save fuel andfuel costs, since it will hold theheat longer and more efficiently thanconventional country kilns made ofloosely piled bricks.

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Earth in many tropical and sub-tropical countries has properties,which combined with hot sun and dryair are favorable to making durablemud bricks, blocks and mud walls.Clay and sand are essential. Clay byitself shrinks and cracks; clay mixedwith sand in proper proportions willreduce shrinking and cracking. Toomuch sand in the mixture weakens theclay and makes it too soluble. Thusno more sand should be added to theclay than is absolutely necessary. Ifthe best bricks you can make withoutcracking are too weak, one solutionis to add plenty of chopped grass,straw or hemp to the mixture, and mixvery thoroughly.Digging Clay for Brick-Making: Brickclay should be dug early in the dryseason because it is much easier tohandle, due to the moisture contentof the soil, and requires the addi-tion of less water to make mud.The builder has a simple device fordetermining and maintaining the pro-per proportions, mixtures and mois-ture content, and that is the deviceof Cosma's Clay Pit, designed by Bro-ther Cosma of the Kiteredde Construc-tion Institute. It is a hole in theground with a technical purpose.

First, the builder clears away allthe shrubbery and extraneous materialfrom the plot of earth he intends touse. He then digs a pit with two orthree vertical walls running acrossits width or length. (See Figure 3).As he digs, he cuts through two l-y-ers of soil, one of sand and anotherof clay. He maintains one depth forthe length of the channel created bythe first vertical dividing wall, andtests the clay produced at that lev-el. He then digs a slightly deeperchannel across the clay pit to testa different mixture, as shown in thedrawing. Eventually through thisprocedure the builder will reach thebalanced mud mixture he is seeking.When the testing proves that the pro-portions are correct, he should al-ways dig his clay pit at the samedepth. It may take from three tofive different testing channels tofind the proper depth and mixture butit is worth the time and effort ifthe purpose is to make bricks of goodquality. In some cases, the blend ofsand and clay is so ideally balancedthat once the proper depth is known,it can be dug and used indefinitely.

I. CLEAR PAPY RLJS.2. DIG PIT. AFTER SEVERAL HOURS OF PlbGIN6, WATER MAY SEEP IN. COtqTlNdETD

EXTRACT CLAY AND WA7ER UNIX- WATER \5 SEEPlNb IN FASTER-I-HAN CANBE BAILED. ABANPON PLY.3. DIG NEXT PIT, CONTINUE PROcESS OF EXTRACTION.

Figure 39


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Processing the clay: The builderdigs and mixes the mud about six toten days before he wants to startmaking bricks or start building withit. First, he prepares a mat of ba-nana leaves upon which to build themud pile, because the leaves willhelp to retain the necessary moisturein the clay.As the clay is dug out of the pit, itis piled on the mat of leaves nearthe pit. It should be mixed aroundby one's feet to detect visible im-purities, and these should be takenout. (Figure 4B). The clay should bepiled in three to five foot stacks.Once the clay becomes sticky with aconstant consistency in these pre-liminary stacks, it is ready to bepiled in a mound about five feet highand five feet across at the base. The

.-.

next step is to make a hole two feetdeep by six inches in diameter in thetop of the pile, and fill it withwater. Cover with a matting of grassabout 6 to 12 inches thick, and thenmoisten the grass once in the morningand once in the afternoon.After two or three days, remove thegrass and mix the clay again withfeet and hoes. Rebuild the stack andlet it continue to cure for severalmore days. After 6 to 10 days fromthe first stacking it will be readyfor use. If the clay is too sandy,additional sticky clay can be added.It is very important to mix the claywell each time it is used. No largelumps or stones are permissible inbrick mud, although small stones ofnot more than l/4" in diameter arenot objectionable and may be useful.(See Figure 4A and 4B).

Figure 4B..\a

Brick sizes: It is good practice tofollow some tested method in bricksizes. Bricks require a certaindepth in proportion to their lengthso that they will not easily break intwo. The length of a brick should bein harmony with building measurementsand the width of a brick should al-ways be slightly less than half itslength. The builder should carefullyplan his brick sizes if he does notfollow standard sizes.

Figure 4A

The brick sizes which have been foundmost practical in eastern Africa are:Unburned moulded bricks 9" x 4" x 3"when fired, produce burned bricksready for construction:

8.5 x 3.5 x 2.5.Unburned moulded blocks 12.5" x 6.5"x 5.5" when fired produce burnedblock ready for construction:12" x 6" x 5".

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noulds: In constructing a mould forshaping bricks or blocks, hard woodshould be used. The pieces of woodmust be straight, and either sandedor planed smooth. This is to ensuresmoothness and perfect moulding onall sides of the brick or block. Caretaken at this stage will help to pro-duce an attractive, marketable pro-duct. (Figure 5).The general thickness of wood usedfor making the mould is l/Z". Mouldsmade from hardwood should produce upto 75,000 bricks or blocks before re-placement is necessary. If hardwoodis not available, a strip of lightmetal (tin> can be run along the topedges of a softwood mould to preventwear as the striker moves over theedge to sheer off excess mud.When manufacturing bricks, have asmany as four moulds on hand, if thereare that many skillful men available,and enough labourers to keep thembusy and supplied with clay.

Bricks with Special Shapes: It i6possible without extra CO6t t0 im-prove masonry by the use of roundedcorners. One benefit of the roundcorner is its durablity, in contrastto conventional sharp corners whichare easily damaged, particularly ifmade with mud plaster. (Refer to thisfor openings and parapets).A 6lOtted brick for use against alldoor6 and window jamb6 is a virtualnecessity. The slot accommodate6 thestrip on the frame so that the framewill not shake loose in the wall.(Figure 6).

MULTIPLE MOULDFigure 6AMOULD FOR RbUND COrWFR ti3ULL NOSE) BRIcY

Figure 5A

Figure 5B

SIDE VIEW

Figure 5C TOP VIEW Oic M-ETA2CaC\NER FASTENED To WOULD.

Figure 6B11


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Figure 6C

Calculating Brick Quantities:Calculate the total area of all thewalls in the building you are plan-ning by measuring the total linearfeet (length) of each wall, andmultiply by the height. There aresix standard bricks to every facesquare foot of wall. A simple set ofcalculations will reveal the numberof bricks needed for the job.The area of a gable is the width mul-tiplied by one-half the height. Thetotal area of tW0 identical gable6 istheir width multiplied by theirheight.In estimating brick quantities, donot deduct for openings, such as win-dows and doors, unless there is aspecial reason for doing 60. Extrabricks are always useful, and a sur-plus over and above actual need6allows one to select the best bricksand to discard those which are lesswell moulded. As a general rule, ifone has sufficient time and money, itis worth it to make a few thousandextra bricks.

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SWT BLOCK SCsrWETIN -PLACE

FULL SUES-KIP FASTEHED TOP VIEW OFJAMB SLOT BLOCK

Figure 6D

Table Method of Hand Houlding Bricksand B1ock.s:Table or slop moulding is the mostcommon moulding practice used inUganda today. There are generallythree worker6 involved: the moulder,the layer, and the helper who assistsboth. The procedure is as follows:1) A simple table is made by using a2 by 8 boar4 nailed to two 6 x 6wide poles, which are driven at leasttwo feet into the ground. The tablesurface should be at the level of themoulder's waist. (Figure 7).2) The drying ground must be verysmooth for laying out the mouldedbricks, otherwise the bricks will bebadly shaped after drying.3) The clay mixture should be slight-ly wet.4) The moulder stand6 near the table.At his right hand side is a small pitfor holding water, or a bucket ofwater. At his left hand side is apile of prepared clay.


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5) He takes a clean mould from thewater pit or the bucket, and placesit in front of him on the table.6) He takes a piece of clay from theclay pile and quickly forms it into arough shape equal in size to aboutone and one-quarter of a brick, thatis, slightly larger than a brick.7) The piece of wet clay is raised inboth hands and thrown with some forcesquarely into the mould on the table.(Figure 7).8) The moulder take6 the striker orstraight stick, and holding it at anangle, smooths off the top of thebrick. The excess clay from the topis thrown back on the pile.9) The brick in the mould box ispassed to his left side to be takenaway and layed out on the dryingground. Caution: water is used asthe release agent to help slide thebrick from the mould. Very wet bricks

are easily damaged or knocked out ofshape. Very wet bricks at this stageof the moulding process produce poorsurfaces, and after firing, are gen-erally not as strong as dryer bricks,and usually sell for a lower price.10) After sliding the brick out ofthe mould, the brick should he cov-ered by a handful of grass toprevent the sun from drying it tooquickly, and to keep rain from chang-ing its shape.11) The moulder repeats the process.It is worthwhile to note that thebrick moulder and brick carrier aretwo very important people in thebrickmaking process. The moulder cantell if the quality of the clay i6good or poor as he work6 with it, andthe carrier because he must make surethat the bricks are properly carriedto the drying ground and carefullylaid out with no damage or loss ofShape.The same procedure6 are used forblock making. It is important to re-member that blocks take several dayslonger than bricks to dry out.

Figure 81


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Drying and Stacking Bricks and BlocksThe drying ground must be very wellprepared so that it is smooth andfree from small holes, bumps, stonesand grass. It is preferable to coverthe drying ground with either sand orsandy loam, which is then smoothedoff. It is a waste of effort andtime to locate, dig up and preparegood quality clay, to make firstclass bricks, and then spoil them bylaying them on badly prepared, roughdrying ground.When bricks are carried from themoulder's table to the drying groundin the mould, the layer takes themould and turns it upside down on theground and iifts the mould from thebricks. Sometimes a slight shakingof the mould box is required, butthis must be done gently so thebricks will not lose their shape.Although the bricks are laid closetogether, care must be taken to pre-vent damage caused by pushing newlymade bricks against or into thosealready stacked on the drying ground.As soon as the bricks have been laidout, they should be covered withgrass, and the grass should be damp-ened with water. This prevents thebricks from drying out too quicklyand keep6 them from cracking.(Figure 9).

Within two days after being laid out,the bricks can be turned on theirsides and covered again with grass.After another several days, thebricks should be turned again andplaced on end.

Figure 10After one week to ten days, brickscan be stacked up in an open setting,or in a covered shed which is open onthe sides. If the bricks are stackedin the open, thei? he lines of dryingbricks should run from north to southso that the sun is able to cover bothsides of the stacks. When stacked inthe open, grass can be applied overthe top for protection, particularlyin the rainy season.

STEP=

Figure 9

14

Figure 11


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Reasons for Bricks Cracking:1) Clay not mixed well with water.2) Clay mixture not left long enoughin the clay pile to age.3) Bricks stick to soil of unevendrying ground.4) Too much sand in the clay mixture.5) Bricks are not covered soon enoughafter being laid on drying ground.6) Drying too quickly.The Burning of Bricks jn a CountryKiln.Due to specific economic conditionsin Uganda, and the universal economicconditions in many developing coun-tries, mechanized transport costsrise rapidly with higher fuel costs,and it becomes less practical forbuilding materials, such as bricksand bags of cement, to be transportedfor long distances.The large brickworks located on theoutskirts of large towns, for ex-ample, find it less economical andprofitable to supply potential cus-tomers in the distant rural areas.Rural builders must therefore seeklocal suppliers of basic materials 'who have been able to find and uti-lize suitable sources of raw mate-rials that exist in the locality.Opportunities will arise for thevillage cooperative or local entre-preneur to carry out the small-scaleproduction and marketing of firedclay bricks ax-J iles. The same istrue for the production of cementingand mortaring materials, when suit-able local deposits of clay, lime-stone, pozzolanas and other rawmaterials are available.

In the more remote regions, it may bequite impractical to import eventhose materials with which to build apermanent brick kiln. Anyone who in-tends to make fired clay bricks in aremote location needs to know how toconstruct a kiln in which to fire theinitial batch of bricks. Such a kilnmay also be the convenient and prac-tical way to test the quality of theclays from selected deposits in thearea for the manufacture of ceramicproducts.

Large Country Kilns:Large country kilns have been used inmany parts of the world, and althoughthey are not as efficient as perma-nent kilns, millions of bricks havebeen produced in them. Fuel consump-tion has been a problem, since manycountry kilns are inefficient aridwaste precious wood. Properly de-signed, however, their efficiency canbe raised considerably, and theirfuel consumption can be maintained ator near the levels reached in moremodern firing systems. The relativelack of controls on burning, comparedwith other production methods, aswell as the fumes emanating at groundlevel, have often made these kilnsunpopular when located in or nearresidential areas.Small Country Kilns:Af this point in history, small kilnsare very useful in Uganda. A smallkiln is suitable for use by the smallcontractor to fill his building needsor by a farmer to supplement his in-come while his crops are growing. Asmall kiln can be the first stage ofdevelopment of a small brick factory,and in fact is a small factory.The design and performance of a smallcountry kiln are interesting, due tothe well-insulated walls. Their de-sign not only effects savings in fuel

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consumption, but also promotes a uni-formity of firing in the bricks, asis evident when such a kiln is dis-mantled.A small country kiln can have a ca-pacity ranging from 2,000 to 10,000bricks. For a kiln designed to pro-duce 4,000 bricks, the external di-mensions are 2 meters long by 1.5meters wide, and a maximum height of2 meters, equal to 20 layers ofbricks placed on edge. A singlefirehole runs the length of the baseof the kiln, though it is open at oneend only. This firehole is approxi-mately 500mm wide at its base by 400mm high, or in other words, two bricklengths wide by four brick widthshigh at the middle.The bricks of the first five layersare laid with their stretchers acrossthe kiln (length-wise). Above this,the bricks have alternating direc-tion, that is, either laid parallelto the length of the kiln, or acrossit. Up to the twelfth layer, lengthand width are constant. Above that,the kiln tapers in a pyramid shape tothe twentieth or topmost layer.Surrounding the kiln on all fourouter sides, up to the twelfth layer,are other sun dried bricks. Theseform a double cavity insulating wall.The inner cavity is continuous, andfilled initially with coffee or ricehusks, sawdust and woodchips, orother agricultural residue. Theseare heaped on the other parts of thekiln, as well, to provide additionalinsulation. Eventually the residueburns during the firing process, butby that time it has served its pur-pose, and the resulting ash continuesto conserve the heat in the kiln.Woodlogs are burned in the firehole.The amount of fuelwood consumed isapproximately 60 to 75 meters forevery 20,000 bricks. To reduce thecutting of standing timber, it should

be possible to add sawdust/woodchips,coffee/rice husks or other agricul-tural residues, to supplement fuelrequirements and reduce the volume offirewood which must be burned tomaintain adequate heat levels.

The fire is built up slowly while theremaining moisture in the bricks isbeing expelled, in what is known asthe "water smoking" period. Afterthis the tntensity of the fire isincreased. The addition of fuellasts for approximately two tsfour days, and then the firehole isblocked off. The kiln is allowed toburn itself out and to cool down.During firing the sides of the kilnfeel only slightly warm, demonstrat-ing the effectiveness of the insula-tion. Heat escapes only from thetop. Obviously, the bricks formingthe cavity walls are not properlyfired, but they can be used again forthe same purpose, or else placed in-side the kiln to be fully fired thenext time the kiln is used.Usually the kilns have the disadvan-tages of lack of control over thefiring. In windy conditions, theburning may be too fierce and causepartial melting or slagging of thebricks. A remedy for this is plas-tering the exterior with mud toprevent drafts, and this is fairlycommon, but this means that the"plastered" exterior bricks areruined and not worth refiring.The country kiln is usually so wellinsulated that once the operator haslearned, by experience, how much fuelto use, the burning proceeds uniform-ly in any kind of weather conditions.During the rainy season, a roof canbe added above the kiln. Simple poleframe construction with palm or bana-na leaves, papyrus or thatch willmake an adequate roof.Apart from items such as a simple

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roof, little or no capital investmentis needed, which is a main advantageof the country kiln, The process,from moulding the bricks to unloadingfinished bricks from the kiln, needtake no more than three weeks for a4,000 to 1For thoseprojects isource ofshrinkage

0,000 brick kiln.responsible for small-scalen remote areas, once amouldable clay of lowhas been located, the mostconvenient means of completing anevaluation of the local raw materialsmay be simply to fire some brick in acountry kiln. It is an appropriatemeans of getting production startedwhen the capital for construction ofa proper permanent kiln in lacking,as it often is.

Kiln ConstructionFiring the kiln is the end-point ofthe brick-making process, and is thecomponent which governs whether ornot the bricks will be durable andstrong. At the point when firingbegins, money, time and effort havebeen expended to making bricks ofgood quality, and therefore it isvery important to remember three mainpoints: (1) fire only good bricks,not cracked or badly shaped bricks;(2) use good quality fuels for burn-ing; and (3) build an efficient kiln.

In constructing a kiln, begin withwell drained, dry ground. A firedbrick foundation can also be used asa base for the kiln. A brick base iseffective as an insulator. It can beleveled easily, and avoids mud andexcess dampness in wet weather.The overall length and size of thekiln depends on the number of bricksto be fired. The width of a countrykiln should never be greater than 15to 20 feet, mainly because fuel con-sumption increases with the size ofthe kiln, and size increases labor,costs and construction time. InUganda, the width of an average kilnof this kind is 8 to 12 feet, onceagain depending on the number ofbricks to be fired.A country kiln consists of threeparts:1) The legs, which form the lowersection around the fireholes;2) The main setting or body, whichforms the bulk of the middle sectionof the kiln, which is built by alter-nating rows of headers and stretchers(bricks laid lengthwise and endwiseon alternating rows), with spaces be-tween the rows of headers. (Fig 12C).3) The outer cladding or shell, whichis made by bricks set close togetheraround the outside and the top of thekiln, and sealed with mud. This formsan insulating casing around the main

BRlC@ BEINGPILED INTHE KILN.LEAVE AT LFAST /,PACE cVOUN DEACH EmCK.

Figure 12A

body of the kiln.GROUND PLAN OF BRICK KILN

Figure 12B

d

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Figure

1157 1 610 1 914 1 610 1 914 ) 610

Construction of the kiln is startedby setting out the first 5 layers orcourses for the legs, beginning witha stretcher, breaker, stretcher, andbreaker until the 5 courses are com-pleted.The next 3 courses are corbelled (seefigure) to form arches over the topsof the fireways.From the 9th course up to the last 2courses, each row of stretchers andheaders has a l/2 inch space betweenthe bricks. Each alternate coursefrom the 9th row up is set at rightangles to each other, which has theeffect of making a checker-work ofbricks allowing heat to pass throughand keeping the bricks in good shape.The last two courses are set closertogether to help hold the heat, butin such a way that they are not tooair tight, keeping heat from flowingproperly upward.A basic height for the kiln is 12 to15 courses, but can be built higherto accommodate a larger number ofbricks.

12c

brick lengthswidth 1, in inchesI I57 =+-Maxim urn width in millimetresThe outer casing or layer is built ofold bricks and mud, and can includecoffee and rice husks, or sawdust orchips mixed with the clay and mud.Kiln OperatfonIn a large country kiln, while burn-ing 10,000 or more bricks, the drybricks are stacked on edge about 2"apart in rows so that the fire andheat can reach all the bricks and asevenly as possible. According to thenumber of bricks required, one ormore firing chambers are formed byarching the dry bricks to make atunnel about 30" wide and from 15 to20 feet long. The bricks in the kilnshould be spaced so that there is atleast l/2 inch of room between theend and sides for circulation.The firing of the kiln should be donewell in advance of the planned con-struction job. The bricks must all bethoroughly dry before being insertedinto the kiln. The mud plaster whichis coated on the outside of the kilnshould be quite dry before the kilnis fired. After firing, the kilnwill take some time to cool, evenafter the plaster is removed.

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Gather plenty of firewood to avoidthe possibility of running short offuel during the firing period. Careshould be taken to try to loccite hedriest fuel. During the actual firingperiod, one person will have to be onduty all night. Four days may besufficient for the burning of 20,000bricks, but a larger number of bricksmay take longer. The variables hereare (1) the number of bricks beingfired; (2) the efficiency of the kilnand the fuel; and (3) the uniformityand intensity of heat in the kiln. Acertain amount of trial and testingis necessary to establish suitabletiming. The openings to the firechamber should remain fairly wellclosed except when the fires arebeing stoked.To begin the firing process, fill thefirehoies or fireways with kindlingwood at the bottom, and add heavierfuelwood as you build to the top ofthe firehole.The fireholes are lit at both sidesof the kiln, except in the case ofanthill kilns, which are only open onthe front side. As soon as the fireis burning freely, the openings arebricked up, leaving a small hole ineach fireway for air flow. (Largerair holes are required in anthillkilns to allow sufficient oxygen tofeed the fire evenly, and for circu-lation).During the first 24 hours of the fir-ing process, it is very important toburn the fuel slowly. This is done byusing kindling, medium-sized wood andwood pieces, plus coffee and ricehusks. The purpose of initial slowburning is to cause the remainingmoisture in the bricks to evaporateat an even rate rather than rapidlyto avoid cracking and damaging thebricks.After this stage, when steam andvapor is no longer escaping from the

kiln, open the fireways and add majorfirewood to the bed of coals, seal upagain with bricks (leaving air ventsopen for necessary air flow), andallow kiln to burn vigorously.This process will take from 2 to 4days, with fuel being added as needednight and day. The objective is tokeep a strong fire and high tempera-ture at all times, and to bring eachbrick to a level where it is red hotfor an extended period of time. Theactual length of this intense burningprocess depends on kiln size, type offuel and its degree of wetness ordryness, weather conditions, and theefficiency of the kiln.After this intense firing process,the fireholes are sealed up withbricks and mud and the kiln is leftto cool down gradually for about 36hours.After the burning process, removeplaster when it is cool enough to behandled. When the bricks are coolenough to be touched and handled, besure they are carefully sorted out.The best burned bricks are used forthe outer faces of the main walls,and the least well burned bricks arefor partition walls. If burnedbricks are made for exterior wallsonly, the best ones are used for thelower part of the wall, or that partwhich is most exposed to water. Gen-erally, the upper part of the exteri-or wall is protected by the overhangof the roof.Burned bricks are often more brittleand fragile than unburned mud bricks.Therefore they must be handled care-fully. When the time comes to startbuilding the walls, burned bricksshould be drenched with water justbefore being laid in the wall, parti-ularly when cement mortar is beingused, because a dry brick soaks upthe water in the mortar mix andcauses the mortar to harden and settoo quickly.

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Kiln Fuels:Wood (timber): Eucalyptus is verycommonly used in East Africa; woodchips from a local sawmill are alsovery useful. The size of the timbershould be 4" to 8" in diameter, andthe wood should be dried for 3 to 4weeks before being used as a kilnfuel. Dryer fuel wood will providehotter temperatures and more effi-cient burning.Coffee husks: Can be used to startthe kiln fire. This is a good source

Selection and Identification of Woodand its UsageThe selection of timber and lumberfor construction depends l.argely nthe character and quality grade ofmaterials carried in stock by localdealers, or upon the materials whichthe builder may be able to obtain byhis own means. Nevertheless, a basicknowledge of the best kinds of woodfor special purposes will be veryuseful, particu'_arly hen importantwork is being undertaken, and thebest results are desired.Light framing material is usuallyselected from woods that are plenti-ful and cheap, while heavy framing,whenever possible, should be madefrom timber which has both strengthand durability in the highest degree.Since the exterior trim of buildingsis subjected to extremes of temper-ature, and to wind and rainstorms, adurable material that is easy to workwith and is least influenced by thesechanges should be selected. The

20

of fuel if you own the coffee husksand do not have to pay for them, orfor the transportation of them. Thehusks provide a fast heat, but notfor a great length of time, and thusbuild up coals quickly.

Papyrus: Can be used in burning, asin the case of coffee husks, if thekiln is in a region where papyrus isplentiful. Papyrus burns quickly,and is not economical to transport.However, it can be used satisfactor-ily to begin the firing process alongwith wood chips and coffee husks.

fibers should be firm and elastic,without being brittle, sufficient-ly tough to avoid splitting whenbeing nailed into place, and to avoidwarping and cracking after beingerected.Where wood is embedded in concrete ormasonry, or is buried wholly or part-ially in the ground, the primary con-sideration is durability.For floors which will be subjected toheavy work and traffic, the durabili-ty and wearing qualities are primaryconsiderations.When interior finish is to be paint-ed, any sound material that will holdglue or wood finish, and stand upwell may be used, but where the woodis to 'be inished in its natural col-or, by varnishing or waxing, its col-or, texture and quality of grain willusually govern the selection.


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Wood For Special. urposes: The fol-lowing list will. erve as a guide inselecting and specifying the differ-ent kinds of wood for special re-quirements. These species are spe-cific to Uganda, and are ranked inorder of preference based on dura-bility. (Other countries or regionscan fill in each category with localspecies).Light framework, small trusses andscaffolding: EUCALYPTUS, ENKAGO.Heavy framework, large trusses:EMPERWERE, MLJSIZI.Long timber, i.e., flagpoles, polebeam for a .jig oist: EUCALYPTUS.Exterior trim: MUSIZI, PODO.Posts and sleepers in concrete or inthe ground: MAWASA, EUCALYPTUS.Piles: ENZO, EUCALYPTUS.Solid framed doors, sash and wains-coting: NKOBA, OMWASA, MUSIZI.Parquet flooring: MUGAVU, NKOBA.Interior trim: ENKAGO.Furniture: NKOBA.Counter and table tops: NKOBA.

Tfmber Species Most Commonly Avail-able and Used in Uganda: (Othercountries or regions can match localspecies in the various categories).Hardwoods:MWASA - plentifulEMPEWERE plentifulEUCALYPTUS plentifulMUGAVU plentifulENZO plentifulNKOBA availablebut not plentifulOMWASA plentiful

Softwoods:ENKAGO plentifulMUSIZI plentifulPOD0 plentifulMUSENBNE plentifulMUTUBA plentiful, used for

bark clothSoftwood Identification: In most ofthe varieties, look for:

1) Needle shaped leaves2) Evergreen3) Trees bear pine cones for seeds4) Smaller in diameter, 300-450mm.

Hardwood Identification:1) Broad leaves2) Shed leaves once each year3) Trees bear acorns, nuts4) Larger in diameter, 750-1800mm.

As Processed Timber or Lumber:softwood:

1) Light in color2) Light in weight3) Easy to work with, plane,shape, carve.4) More elastic5) Relatively cheaper to buy6) Mainly used for carpentry workand general joinery.

Hardwood:1) Dark in color2) Heavy in weight3) Difficult to work, plane,shape, carve.4) Less elastic5) More expensive to buy thansoftwood6) Used as m;ch as softwood inmany cases for joinery, due tobeautiful natural appearance.

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Wood Treatment: to stop termites,and woodrot caused by damp weather:(local treatment of timber withoutimporting expensive materials).Heat treatment for piles/poles:Put the lower part of the log or

pole that is to be buried in theground into hot coals until the outerbark is hard and turns a black color.Continue to rotate the log until itis finished on all sides. This pro-cess should only take 2 to *3 ours indry weather.Used engine oil:Bury a 200 liter drum 3/4 of theway into the ground. Fill the drum

with used crankcase oil. Lower thelog or pole into the drum and let itsoak for several hours. If a drum isnot available, simply paint or rubthe used oil onto the log or polewith a rag or a local paint brush.

Drying and Stacking Wood:In many parts of the world, dry, wellcured lumber is seldom available,particularly in rural areas. In partsof Uganda, for example, one must tra-vel over a wide area to procure suf-ficient standardized lumber of goodquality for construction. A buildershould plan well in advance, procuresufficient lumber for his needs earlyand dry it properly.There are two characteristics ofmoisture and evaporation in newlyprocessed timber, which the buildershould know:1) Fibre Saturation Point: Aftercutting and drying, the timber stillhas 25% to 35% moisture in the cellwalls. This moisture tends to staywith the lumber for many years.

2) Equilibrium Moisture Content:refers to moisture in the wood due toatmospheric conditions. In the rainy

22

season, the wood will tend to draw inadditional moisture. During the dryseason there will be less moisture inthe wood.Drying lumber (timber) is the removalof water from the timber. Most build-ers know that it needs to be thorough-ly dried before it can be transformedinto a useful product. The twin goalsof drying are:1) Reducing moisture content (M.C.)to a level consistent with the atmo-sphere within which the finished lum-ber will be used, and,2) To avoid damage to the materialduring the drying process, such ascracking, warping and splitting.The objective is to allow wood to doits shrinking and drying before it isused in construction or framing,rather than after the woodworking ormanufacturing process.In stacking and storing lumber, thereneeds to be plenty of air circula-tion. The following drawings illus-trate proper ways to stack lumber fordrying and for storage.

Figure 13A


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1" x 1" x 6' stringers areplaced between each layer of 'boards to allow air circulation.'Bottom layer is placed acrossevenly planed logs to protect ' ~bfrom ground moisture.

Figure 13B

A storage yard with several stacks.. -.,/ of boards, each of manageable height,and separated for ease of access andfor adequate air drying and sunlight.

Characteristic shrinkage and distortion of flats, squares, and rounds asaffected by the direction of annual growth rings. The dimensional changesshown are somewhat exaggerated. (From Air Drying of Lumber: A Guide toIndustry Practices, Agricultural Handbook No. 402). -23


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CRAPTRR IIBASIC BUILDING COKPONENTSIntroductionA house which is satisfactory on onesite may not be as practical, usefulor appropriate in another setting.Therefore it is unwise to make finaldecisions on building design untilthe actual site has been secured, andall its important features are known.A builder should gather informationabout the conditions on and aroundthe housing site in all seasons, withrespect to its suitability in thesecategories, among others:1) Health: Temperature, humidity,altitude; the timing, value anddirection of winds; soil erosion;swamp; rainfall; the prevalence ofdisease; proximity to unsanitaryconditions over which the builder hasno control; depth of soil; the pres-ence of large masses of rock whichradiate heat; the presence and valueof trees; whether the site is on ahill, or in a plain or valley; itsproximity to other buildings, and thecharacter of those buildings; theavailability of safe drinking water,and also health and medical care.2) Work: Accessibility to and fromother people, centres of populationand appeal; proximity to place ofwork, or to other work opportunities;government favour.3) Building conditions: Inquireabout supplies, labour, weather, thebuilding by-laws, restrictions, andthe plans for future developments inthe area. Occasionally a site orarea is found which is quite unsuit-able for building a house or a com-pound, for one or several of thesereasons.

4) Environment: This is particularlyimportant in areas where many housesand buildings have been built al-ready. The builder, when planning fora site, should take into considera-tion the proximity of the site tocongested areas, and such factors asnoise, traffic, fumes, and generalcleanliness and sanitation; roads,rivers, nearby institutions, schools,and public transportation are also tobe considered.Once these issues and the necessarylegal or title documents are workedout with the appropriate authorities,the builder can begin. The followingpages describe some of the basic ele-ments of construction, making use oflocally available materials.

FOUNDATIONSThe choice of foundation type dependsupon the nature of the site, soil,climate, style of the building, thelocal construction codes, the avail-able materials, the skills of thebuilder. Some types of foundations:Concrete Perimeter: (Figure 15).Advantages:1)2)3)4)

Conforms to most local codesNo engineering requiredMonolithic, solid, resists tremorsCrawl space protected from weatherand debris5) Good in most soils6) Good on level sitesCONCRETE PERIMETER ( WOOD FLOOR)

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Disadvantages: CONCRETE SLAB1) Careful framework essential2) Considerable excavation needed3) Requires volume of on-site con-crete mixingConcrete Piers: (Figure 16).Advantages:1) Minimal excavation and formwork2) Good on sloping or steep sitesDisadvantages:1) Leaves underside of house open2) Engineering often required forcodes.

CONCRETE PIERS

Figure 16Concrete Slab: (Figure 17).Advantages:1) Same as concrete perimeter andpiers, plus,2) Floor close to ground level3) No floor or foundation rot4) Water will not damage floor, easy

to washDisadvantages :1) Not adaptable to steep site2) Damp and cold if improperly built3) Requires fill where high watertable exists4) Requires considerable on-site man-power and skill to mix, pour andfinish.

Figure 17

Wood Poles: (Figure 18).Advantages:1) Good on slopes and steep sites

where no cement is available2) Does not require excavation ordisturbance of site3) No cement forms needed4) Practical in remote areasDisadvantages:1) Poles will rot eventually, butcan last up to 75 years with pro-per treatment2) Not good in soft, wet soils3) Deep holes may be difficult todig, depending on site, sub-soils4) Leaves underside of house open.

WOOD POLES

Figure 18The following section provides infor-mation about each of the four typesof foundations mentioned here.

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LAYING OUT A FOUNDATIONThe diagrams below illustrate some ofthe important aspects of accuratelylaying out a foundation.Shown in the diagrams are batterboards. These are set back about 4'from the building lines to supportthe strings which provide the accura-cy in layout which is essential inorder to avoid problems later on. Thestrings can be removed when working,dG@mz, and building forms, and thenreset to check measurements.Procedure:Using a 3-4-5 (6-8-10) triangle toget right angles, lay out a roughoutline of the building with corner

Figure 19A

Drive three stakes about 4' back fromthe corner stakes for batterboards, asshown in the diagram. With a level,water level, or line level, mark thestakes all at the same level.Nail boards (1 x 4s) onto the stakesat the level marks, and brace allboards to prevent movement.Lay out exact measurements of thebuilding, using nylon string, ifavailable, or other string, withloops stretched between nails on thebatter boards. Use 3-4-5 triangle toget four strings in place, and thencheck diagonals, adjusting the

TAUT STRING ,BAITER BOARD

BUILDING LAYOUT LINEFigure 19B

IF BUILDING LAYOUTIS SQU,4RE, , DIAGONAL;I--;;5 WILL STRIN 65 MARK

LAYOUT OF BUILDING LINES ;STRING.5 MUs-r BE LEVEL

Figure 19C


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strings until measurements are accu-rate. On sloping building sites. thebatterboards will need bracing.Water level: Use a length of gardenhose, with a short section of clearplastic tubing taped onto each end(it must not leak). Cap one end whenmoving the hose. Ends must be openwhen reading level. The water in thehose will seek its own level and willgive accuracy readings to withinl/16" in 100 feet. (Figure 19D>.

Figure 19D

No. of storeys 12 3Thickness of foundationwall in inches 6 8 10Width of footing-inches 12 15 18

Thickness of footingin inches 6 7 8Depth of footing belowgrade(surface)-inches 12 18 24

Inexperienced builders may find iteasier to first pour the footings,then build forms for stem walls ontop of the footings, after the con-crete has set. Experienced buildersusually pour footings and stem wallsat the same time.

MlrD SLLL

ANCI-IOR 30 LT

STEEL(REBAR)1F AVAIiABLE. -40AMBO0, BARBEDWLRE ANP OTHER TENSILE MATEFJALSCAN BE USED WITH CAUTLON.Figure 20A

A. Concrete Perimeter FoundationH\llS\DE S\TE : POCYi-INGThe basic parts of a perimeter found-ation are the footings, whi.ch preadthe weight of the building uniformly

over the ground and the stem wall,which supports the floors and wallsabove the ground level.Note: interior weight-bearing wallswhich support the weight of the roofmust be supported by continuous foot-ing with stem wall and mud sill, orpre-cast piers, girder or beam.

Figure 20B28


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Excavating, Pouring, Forms:.I...Jl

1...,. I.. .LEFT: FOOTING WITH KEYPUDDLE: S-I-EM WALL PCHjREDON TOP OF FOOrlt4GRlGhT: FOOTING AND STEP4WALL POUR.ED SAPIE TIME

Figure 2OC

RElNFC+tCING STEEL :SHALLOW STEPS, ,4S ABOVE ;STEEPER STEPS, AS BELOW.

Figure 20D

FOOTINGS MUST DEAR ONUNDlSTURBED FlRM SOIL

FIRM SOIL: NO FORM BOARLXRE 9 UlRED.PoUR CONCRETEDIR CTLY IN TRENCH.

tO05E SOlL : FORM BOARDSREWIRED. A 2 x 2 IS PRFSSI~DINTO THE Wf3- CoNCRETETO FORM KEY.Figure 20E

Using strings, mark lines on groundfor digging, with lime or powderedchalk. Careful digging can saveconcrete. Throw the dirt well backfrom the building lines to leaveample room for working. Be sure thebottoms of the trenches are level bychecking with a carpenter level plac-ed on a board or 2" x 4".Pouring: Reinforcing steel, ifavailable, or old fencing wire orother metals should be in place about3" above the bottom of the trench, atleast 2" from sides of wood forms.Wet the earth in the trench beforepouring concrete so that the dry soilwill not draw moisture out of theconcrete.After pouring, smooth off and levelthe top of the footing (upon whichthe form wall will rest). Put a twoby two on edge in the wet concretefor a key to level. Be sure there isvertical steel (hooks under horizon-tal steel) every 18 inches.Building forms:The forms for the stem wall are builton top of the footing, which has akey and vertical steel, to tie foot-ing and wall together. Forms arefilled with concrete to the top. Thusforms must be accurate in height aswell as horizontal measurements. The2" boards commonly used for form lum-ber, are later stripped away from theforms and used as joists.Steel form ties are commonly used tohold forms together while forms areunder pressure from concrete. Theyremain under the concrete after itsets. The ends are broken off afterforms are stripped away. Wire orwood batts can also be used to holdthe forms in place.

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Procedure:1) Using strings, build outside formsfirst. Use builder's level orwater level to make sure the formsare level all around. Use blocks orstones to raise forms if necessary.2) Check diagonals; adjust if neces-sary; accuracy is important here.3) Insert steel ties, wire or woodbatts.4) Bend horizontal steel and lay inplace before adding inside to form.5) Build jnside forms.

6) Raise and tie steel as forms arebuilt.7) Suspend anchor bolts in place.

Reinforcing Steel: Depending on wallheight, two or more l/2" bars of re-inforcing steel (rebars) are hunginside forms with the wire from thesteel ties. (Figure 21A and 21B).

BUILDING FOFWS ON TOP OFALREADY POURED FOOTING

Figure 21A

BUILDING FORMS WtiEREF00TING /#II STEM WALLS TOBE POURED AT SAME TIME.(FOR BUILDERS WI-W SOWE FORM-WIL-iJIf'lGXPERII~NCE.)

Figure 21BPouring Concrete:Formula when mixing it yourself: 3parts gravel; 2 parts sand (sea sandis best); 1 part cement. The lesswater, the stronger the concrete.Keep it stiff.Procedure:1) Have 3 or 4 helpers with as manyshovels. Rubber boots and woodfloats are needed, and a large wheel-barrow is very useful.2) Spray or sprinkle the ground andforms with water just before concreteis poured.3) Pour In layers. Pour bottom ofthe form all the way around first.This gives it time to set up, andminimizes pressure and leaks.4) If concrete starts oozing from theforms, it can often be stopped byshoveling dirt against the side ofthe form that is leaking, and pouringat some other point along the formfor a while.

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5) Tamp or puddle concrete in formswith a 1 by 4 to ensure good fill andto eliminate spaces.6) Tap side of forms with a hammerfor smooth surface.7) When form is full, trowel off thetop smoothly. The mud sill will resthere. Check anchor bolts for rightheight and vertical angle.S> Clean off all tools immediately.9) Strip form after 24 hours. Keepconcrete covered and damp for threeto five aays.

Openings in Concrete: An opening ina concrete wall must be blocked outin the formwork before the pour.These are usually rectangular open-ings with stringers left in. Ventsand apertures can have many uses, anduse determines the size needed: crawlspace to allow one to get under thebuilding; vent opening for good vent-ilation to help minimize termite anddry rot damage; vents for plumbingand wire openings.GIRDER SUPPORTS

B. Concrete Slab FloorsIf well built, a concrete slab floorneed not be damp and cold. Concretehas a high heat storage capacity andcan be built to avoid dampness.Procedure:1) First build a standard footing andstem wall up to a desired height.Omit all vent and crawl space open-ings, but allow for sewer, water andelectrical lines, which must be in-stalled in the floor and/or founda-tion wall before concrete is poured.2) Remove all organic material fromthe floor area.3j Put down 4 to 6 inches of one andone-half inch gravel.4) Roll out 6" by 6" welded wiremesh, or place 3/8" rebar 18" on cen-ter each way, if available.5) Install any plumbing, wiring orpipes where they should be in theconcrete.6) Set anchor bolts.7) Set wood screeds either temporari-ly or permanently.Note: Interior bearing walls on slabfloor must be supported by footingthe same size as exterior footings.

LEFT: POCkET FORMED BYBLOCKING OUT INSIDE FORM.R\GHT: ANCHOR BOLTS #OLDTREATED WOOD SUPPORT.Figure 22A

TEMPORARY SCREED IS 3AKED ABOVE SLABLEVEL FOR EASY REMOVAL AFTER POUR.MAXI MUM EFFECTIVE LENGTH FOR STRAIGHTEDGEIS IO- I2 FEET; USE TEMPORARY SCREED A5ABOVE WHEN POUR 15 WIDER.

REED

Figure 22B Figure 23A3


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REINFORCINGSTEEL, HAVE USED BAtiBC0PND 04fXBED WIRE.

Figure 23CSTRAiGHTEDGE \5 WORKED BACK AND FoRr7-1 TO BRINGCONCRETE TO ROWH FINlSH LEVEL. AFTER 7\llS, USEWOOuEN FLOAT, THEN STEEL TROWEL TO FINIS/-~.PULL MESH UP DURING POUR (IF A/AILABLE).

Figure 23B

The Concrete Pour (BriefInstructiolls):1) Pour 3 and l/2" finished floor.2) Rake off level with a 2 x 8 rest-ing on screeds.3) Smooth off with large wood float.A film of water will rise to the sur-face. When this evaporates, the slabis ready for the steel trowel.4) Continue trowelling until surfaceis smooth and hard.5) In hot weather, shade your newlypoured concrete if possible.C. Cast in Place Concrete PiersThe main advantages of piers are themimimal formwork necessary, and theirsuitability to sloping sites. Thereare three ways to utilize them:1) With regular footing, if height ofthe concrete pier is less than threetimes the diameter of pier, and ifpiers are spaced six feet apart.

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SLAB

Figure 23D2) With a grade beam, that is asteel-reinforced concrete beam atground level that acts as a bridge totie all the piers together.3) With deep holes and no connectingfooting or grade beam. In this case,the weight of the building is part-ially supported by friction of thesoil around the piers. Holes areusually six feet to twelve feet deepdepending upon soil conditions andthe height of the pier above ground.It may be advisable to get some helpfrom an engineer in this case.The following is a simplified systemfor using concrete pier foundations:1) Check with local builders regard-ing footings, footing sizes and depthneeded.2) Dig footing trenches.


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3) Enlarge footing trench around eachconcrete pier. If the site is flat,forms are probably not needed. Ifthe site is steep or sloping, step-ping may be required. (Figure ZOB).4) Lay 2 pieces of steel in trench,supported about 3 above ground.5) Wire 4 pieces of vertical steel ineach pier area. (Figure 24B).6) Pour trenches.

CAST- IN LACE CONCRETE PIE RFOUNDATrOt4

Figure 24A

D. Wood PolesWood pole foundations are especiallysuited to sloping sites where con-crete work is difficult, or in inac-cessible sites. Also, in terms ofaffordable, low-cost construction,pole foundations may be the mostpractical solution for many builders.In some areas, properly treated polesare said to last from 50 to 75 yearswithout rotting.

7) The next day, place forms overpier locations. Plumb them at thedesired height, and brace with 1 x 4sif necessary.8) Insert vertical steel with 2" attop for the insertion of anchorstraps for posts or girders.9) Throw some dirt around the base.10) Fill with concrete. Be sure topuddle with sticks to eliminatespaces.

TYPICAL CAST-IN- PLACE COLUMN

A REBAR TIES AT24 0.c. ti0~l2Ot4I~~

Figure 24B

The number, size of poles, depth be-low ground and spacing are determinedby soil conditions, and of course,the size of the building.The same procedures described forother foundations, particularly formeasuring angles and leveling, areappropriate here.A typical pole foundation treatment

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would have a 6 foot hole with an 8concrete footing at its base to sup-port the pole. After the pole is in-stalled, the rest of the hole isfilled with tamped sand. (Figure 25Aand Figure 25B).

WOOD POLE FOUNDATION

60 DEEPF 12" IAM.TREATED POLE

8 CONCRETE &FOOTING

7 24" PIAt-HOLE. FILLs ::: TAMPw

Figure 25A Figure 25B

TYPES OF WALLSEcomomy demands that one make thebest use of materials, local or im-ported. It may not always be wise tobuild with the cheapest materials a-vailable, if the objective is sound-ness and durability. It is worth de-voting time to inspecting a varietyof buildings and the materials usedin them to see which ones withstandthe test of time. It is possiblethat by gathering such information,one will be able to discover materi-als in the locale which will providedurability at reasonable expense.A few suggestions are offered herein this section about different typesof walls. An examination of varioustypes may be useful in determiningthe kind of wall best suited for thebuilding being planned.

TYPICAL POLE

4 OR 6Cl RDERSLET 1N l-0POLEMIN. 3

Mud or Adobe BrickMud or adobe has been found to be oneof the most practical types of wallconstruction, where the clay is suit-able I and where there is enough dry,hot weather to bake the brick.Mud bricks are adaptable to almostall building requirements, exceptwhere conditions bring about constantwashing or splashing of water. Mudbricks lend themselves to corners,jambs , arches a,ld ther awkward wallwork, as well as straight wall work.On a proper foundation, mud bricksmay be classed as sound and permanentconstruction.The greatest drawbacks are their in-ability, more in some locations thanin others, to withstand rain, andtheir complete vulnerability to the

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ravages of the termite or white ant.The first problem has been overcomein some areas by waterproofing themud plaster with cotton seed tar,which, when dried, will hold cementwash, which in turn is a satisfactorybase for lime washes.In some instances, a weak cementplaster has held to the mud brick asa protective coating, but this seemsto be the exception rather than therule. The different rates of expan-sion and contraction of mud brick andcement plaster causes the latter topeel away from the face of the brick.Brick sizes are provided in thechapter 3n brickmaking. (Chapter I).

Mud BlockMany builders prefer mud block to mudbricks. They lay faster and on agood foundation may be regarded aspermanent construction. They requirespecial bonding at the corners togive strength, and they are definite-ly not as satisfactory as mud bricksin respect to odd measurements, awk-ward corners and special features.

Burned BricksThese have been used where cementplaster was considered a requisite,or where the mud was considered to beof such poor quality that mud brickswere not satisfactory, or where goodclays are abundant. Considerable timeand skill are needed to produce goodfired bricks, they take longer tomake than mud bricks, and often haveto be transported for some distancefrom the clay source and kiln to thebuilding site. In main house walls,their size involves a three brickwall, which is thicker than the stan-dard mud brick wall, and such wallsare obviously more expensive. Burnedbricks are not always completelywaterproof. It seems likely that

clay lacks the properties necessaryto be an absolutely impervious mate-rial.Concrete BlockIt is hardly necessary to list theadvantages of this type of construc-tion. Concrete block is indestruct-ible as far as water and rain areconcerned. It is ant proof, cleanand strong, and is always acceptableto the authorities and to buildingcodes. It is, or ought to be, veryattractive and esthetically pleasing.Another great virtue of concreteblock is that it can be used for con-struction anywhere at any time. Butit has the significant drawback ofhigh cost. Particularly in regl9nsand locales remote from railways,roads and centers of production, thecost of the cement alone is invariab-ly prohibitive.Block-making machines are available,but they are not without their draw-backs. Very few workers care to makea block mould. They are very heavy,and the process requires scores ofmetal pallets, further adding to theexpense of the operation. The lay upis also expensive, if the work is tobe done neatly.Despite these disadvantages, somebuilders have ?earned by hard exper-ience that the desire to save moneyby using other materials has resultedin so much continual patching ofwalls made from other materials, andrelated problems, that a concreteblock building might have been moreeconomical and better from many pers-pectives. This does not apply to allbuildings, of course, but particular-ly schools and public buildings,which should be soundly and attrac-tively built at the outset. In suchcases, the initial cost of concreteblock might represent a savings overa long period of time.

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Stone Walls Veneer WallsIn many places, stone is the mostpractical material for footings andfoundation walls. At the same time,it has not always been recognized asa very expensive material for walls.It does not lend itself to finemeasures, jambs and special features.It is costly to lay up properly, andmust be pointed up with cement, whichis another costly item.If cement plaster is used on the in-side, there is the added expense offilling in large cavities with costlycement. Stone walls must be thickerthan mud brick walls to provide thenecessary stability.On the other hand, a well built stonewall is permanent, attractive andsubstantial. It may be a necessitywhere mud is unsatisfactory, wheregood clays are not available, andwhere stone is relatively inexpensiveand plentiful.

Corrugated IronThis type of wall is not commonlyused for dwellings, but for certainother types of structures it is oftenthe most practical. It has someunique properties. It can be builtin a day or two. It is waterproof,and when fastened into place, neverrequires attention or repairs. Itis durable and can be used at alater time for a different purpose.It can serve as a dwelling house wallvery acceptably for a year or two ifit is backed up by mud, which in turnis plastered. As in the case of con-crete blocks, this type of wall canbe put up anywhere at any time. Ifskilled labour is not available, onecan do it alone, since installationdoes not require heavy work.

The same principle mentioned in re-lation to corrugated iron wails, thatof backing the iron with mud, appliesto burned brick and to concrete blockwalls. It is possible and permissi-ble to build a thin outer course ofwaterproof brick or concrete blockwith a thicker backing of mud brickor mud block. This is a veneer walland is strongly recommended as asolution to many problems. It isimportant to mention that one of theessentials to good construction ofthis kind is to provide frequent andadequate ties between the veneer andthe backing, either by iron, or bythe more satisfactory method of head-ers or cross blocks and bricks.

Pise or Ramned EarthIn this method, slightly damp soil isused as a removable form or mould.When the form is full, it is takendown and set up to be filled again.The chief factors in determiningwhether this type of building con-struction should be adopted are:builder's preference; climatic con-ditions; the presence of the rightsoil; shrinkage; the scarcity or com-plete lack of bricklayers; the abil-ity to make and properly handle themould; cleanliness and reducedhandling (as contrasted with bricks).

COIQOU Mud WallsThis type of wall is remarkably dur-able in some locations. Although itis not recommended for the walls ofpermenent dwellings, it should not beignored as a possible material forthe walls of other kinds of struc-tures. It makes a practical wall ifbuilt upon a solid foundation, suchas stone, and if it is adequatelywaterproofed. The greatest diffi-culty would seem to be that of

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Construction Using Local Materials