Bamboo in Building Construction

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MICROFICHEREFERENCELIBRARYA proj ect f Volunteers in Asi aA Series of Articles on the Use of Bamboo infillding Constructi oncollected by Dr. Jules J.A. JanssenPublished by:

St ichting TOOLEntrepotdok 68A/ 69A1018 AD AmsterdamTHE NETHERLANDS

Available fromsame as above orIntermediate Technol ogyPublications9 Ki ng StreetLondon WCZE 8HNENGLANDReproduced by permission.Reproduction of this microfiche document in anyfornr s subj ect to the same restrictions as thoseof the original document.


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.

a series of articleson the use of

in building construction

collec?ed by dr. JulesJ.A.Jacs?enUnivemty of Technology EindhovenThe Netherlands


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BAMBOOCICA publication 82.03

collected byDr. Jules J.A. Janssen civ. eng.Committee for International Co-operationActivities (CICA)Sub-Committee MicroprojectsEindhoven University of TechnologyP.B. 5135600 MB Eindhoventhe Netherlands

This publication can be obtained through:

Foundation TOOL ITDG bookshop61A Mauritskade 9 King Street1092 AD Amsterdam London WClE 8HNthe Netherlands England

Second edition, 1982, 400 x.

Free use can be made of tnc? information inthis publication provided the source isproperly indicated.The Eindhoven University of Technologycannot be held responsible for the possibledamages resulting from the use of theinformation contained in this publication.

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In may 1974 manual n b&boo was published, n Dutch.I%is anual on+&ed selected rticles n the experiencesof the catch ngineers n Indonesia uring he colonial eriod,with the building f houses, oads nd bridges. Since hesearticles ave a wealth f practical nfomation, hey ereconsidered o be still seful or fieldworkers.After ublication,everal equests or an English ranslation~ereoeivedand,insteadof~~latingtheDutchtext,similaroriginal~lishmaterialwasbroughttoqether,resulting n a manual or use by field engineers nd ccmumitydevelopnentwxkers n tropical ountries.In1582 IzhisEnglishmnualhasbeenenlargedwith heresultsofrmdemr esearch rograms.

3u3.e~-A. anssen

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chapw1:

2:3:4:5:6:7:8:9:

Intmduction; dvantages nddefectsof bambx; pmsem&icnHousingBridgesRoads -HoatsandFbftswater SuPPlYHanlbooonstnlctionsBanhmreinforcedconcreteReferences nd index

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chapterl. : Introduction1.1. -Advantiges nddefects fbahoo,basedon

thepublicationsbyMATIIuRand~ P* 5- Preszcvationf bamboo.

1.2. -First, amre fun&mm tal article yPmf.dr. W. Liese n Gate (1981) o. 1

1.3. - Next, practical mnual, ages 0...24and 26 fran %anualof ruralwocdpreservation"(Anyba3y ho is intesested n preservation,isadvisedlmorderhiscopyofthismanualat the address:Forest roducts esearch entreP.O. Bax 1358EXXOKOPapua ew Guinea),

Pm 9

p. 12

1.4. - At last, ages 2 + 93 fran the U.N.IMIlual p. 18

Note: this ook refers obad inbuiPding tructures.Hmever, anyreadertiois interested nthecultivationofbamboo, isaskedtolcokintothe indexandthereferences n this mk, chapter , page 177.


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.a1 : In 1953 r. F.A. McClure ublished is book '&n-boo s a buildingmaterial". ref. 0) Frcxn his book follow he "Introduction"nd

a descriptionm different amboo pecies ight e.Introduction

Bamboo is one of the oldest materials usedby mankind to increase comfort and well-being. In tudeys world of plastics e.nd steel,bamb continuer to make its age-old con-tributions end is even growing in importance.Programs of technical cu6peretion amongnations are giving recognition to the uniquequalities of bamboo and are bringing about abroad sharing of the varieties of bamboo andthe knowledge pertaining to their u se. in sixLatin American countries, project5 are goingforward tuday to test end select outstandingvarieties of bamboo gathered from over theworld and to determine their potectiai piecein local economies. These projects, n ow apart of the Point Four program of technicalcooperation, have been under way for a num-ber of years end some of them have devei-aped to a point where bamboos multiformusefulness has become obvious end chelieng-ing.

Bamboo is a versatile pient material,whose potential can he harnessed in the ser-vice of the humble es well es the greet. inits adaptability to human needs, it has fewpeers in the plant kingdom. in the Occidentas well as the Orient, the peoples in whose

envirtsnment bamboo is a natural featurehaae nmpiy de.moastr.ated its claim to a spe-cial place in their everyday life.

A.5 technical cooperation continues tosing.ie out spec,i.es with outstanding utility,.end to dissem.inate them more widely, alongwith the old skills end the new techniquesessential to their practical use, the lot ofmany now underprivileged people will defi-nitely be improved. With a few plants ofsupeior bamboos in the backyard, a familywill have et hand the wherewithal to fencethe garden, build a pigpen or chicken coop,or add a room to the house. They will alsohave the means of augmenting their dailyincome by making baskets or other speciai-ties iri spare time for sale or ex.change etthe market.

If techniques of large-scale, mechanizedutilization can be developed-as, for example,in the manufacture of high-quality papers andrayon-new industries end increased nationalincome may be brought to underdevelopedareas, It is with these prospects in viewthat bamboo is being used es one of the ve-hicles for implementing the Point Four pro-gram.

Differences Among SpeciesAs with steel, bricks, cement, stone,

clay, timberwoods, or any other buildingmaterial, it is necessary to think of thebamboos in terms of individual and distinctkinds, each characterized by a combinationof properties peculiar to itself (fig. 2 3). Certaincombinations of these properties are use-ful for identification; certain ones must betaken into account in evaluating the suita-bility of individual kinds f o r one purpose oranother. Here are some of the propertiesthat determine the best use of a given bem-boo end the relative value of available kindsfor a given purpose:

1. Average dimensions of cuims2. Taper of culms3. Straightness of culms4. Sire end distribution of branches5. Length of cuim internodes6. Shape and proportions of internode57. Thickness of the wood (culm well)

8. Relative proportions and distribu-tion of different tissues (bundles end paren-chyma) in the wood ,(which effect the prop-erties listed under 9 end 10)

9. Density end strength of the wood10. Splitting qualities of the wood11. Susceptibility to fungi and wood-

eating insects,.

Specifications for bamboos are not yetstendarixed on e wide geographical scale.Within any bamboo-using community, how-ever, the close observer will find that wherethere is a choice of several species, cer-tain ones will be used for certain purseswith greet regularity. And where there areestablished bamboo markets, many of thebamboos offered are found to be classifiedinto more or less well-defined grades withdistinctive names. Such markets, end thelocal artisans who work in bemboo, aresources of much useful i n f o rma t i o x i n o tto be found anywhere in print.

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BElmlxmha sdvantages,nddisadvantagesswell. Mathur (ref. )gives sumnary; we start with:

SOME ADVANTAGES OFBAMBOO HOMES

1. Bamboos are circular in shape andsobd or hollow. As such bamboos can beeasi y cut into required size or split up with thehelp of simple tools, This helps in quickconstruction of houses.2. At every joint in the bamboo there is across partition wall on account of whichbamboos at their joints are very hard and donot bend or break easily. Bamboo houses are,therefore, strong.3. The texture of bamboos is such thatthey possess a high tensile strength ; they areelastic and as such seldom break,4. The dimensions of bamboo-its lengthand thickness-are such that bamboos can beconveniently stored and easily used in construc-tion. . oh account of this, construction ofbamboo houses needs less skilled labour.5. The surface of bamboos is hard and clean. The colour ofbamboos is also pleasant, This gives a good appearance to bamboohouses.6. Bamboos have neither bark nor any material which goeswaste. Therefore, bamboo can be used readily as such for houseconstruction. Even though treatmeni of bamboo is desirable.7. Bamboos cost very little and in almost every part of ourcountry bamboos of good quality are available at cheap rates.Bamboo houses are, therefore, cheap.8. When treated bamboos are used for construction of housesand when such houses are maintained properly it is found thatbamboo houses have sufficiently good life.9. Bamboo houses are comfortable to live-in in hot and dry

climates as they provide adequate protection from heat.10. Bamboos are light in weight, As such bamboo houses suffervery little loss due to earthquake. If such houses fall down due toearthquake, these can be reconstructed very quickly and at littlecost.11. Temporary construction with bamboos can be made Veryquickly at low cart.12. A variety f useful rticles f every ay use like ables,Chairs, Ots,mats,etc.andartisticabjects ordecorationcanbepeparedfranlxmkws. The areveryusefulfordanasticuse.

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Next, z continue ith:SCGEDEFECTSOF-HOUSES

The houses onstructedithbamboos ave sme defects hicl- redue to the follming:1. (a) I&e to dampness he bamboostarts ecaying nd rotting ery soon.

(b) Termites and borers attack bamboos and by eating it makeit hollow. This shortens the life of bamboo structure and rendersthem dangerous sometimes. As such, houses constructed with un-treated bamboos may not be very durable.2. When bamboo is buried in the ground, it starts decayingvery soon and is also eaten away by termites and Insects. Therefore,bamboo should not be used in the construction of foundations forhouses.3.time. Bamboo catches fire very quickly and is burnt to ashes in noBamboo houses, therefore, need fire protection treatment.4. With the passage of time, the strength of bamboo decreases.fhis is responsible for short life of bamboo houses.5. in case of even a small impact force, bamboos are likely tobreak and split up, and the houses are damaged.6. Bamboos have joints at different places in its length. There-fore, walls made of bamboo do not have even surface.7. Bamboos are not of equal length and thickness. This presentssome difficulty in construction work.8. Bamboos on drying shrink and consequently their. volumechanges. This has an ill-effect on construction done with bamboos.Some of the defects of bamboos mentioned above can be removedto some extent by proper treatment before their use in construction.The service life of bamboo when treated is increased and the use oftreated bamboos in construction rtsuL ia morz durable houses.

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Finally, he disadvantagess described y McClure, nd hew toov~come them.

Shortcomings of Bamboo and How to Overcome ThemThe culms of some bamboos have cer-

tain characteristics (in combinations, andin degrees, which vary from species tospecies) that limit or reduce their suita-bility or versatility as building material.A careful study of these limitations, how-ever, shows that most of them can be over-come, or minimized appreciably.Variable Dimensions

It is difficult to secure culms veryclosely standardized to any given set ofdimensions. For this reason, the process-ing or .fabrication of bamboo cannot easilybe mechanized, and its utilization generallyfalls within the realm of a handicraft.

With sufficiently large supplies of culmsavailable, the disadvantages of this varia.-bility may be overcome to a certain extentby exercising special care in the selectionand grading of the material. Further com-pensation may be achieved by giving specialattention to the development of skills in thecutting and matching of pieces.Uneven Surfaces

The use of certain bamboos is madedifficult by the crookedness of the culms,the prominence of the nodes, the unevenessof size and shape of the internodes, andthe rate of taper. This uneveness and thetaper, which is more marked toward thetip of- the culm, may make it difficult toachieve a tight, weatherproof, verminproofconstruction.

To overcome the effects of uneveness,the builder should select bamboos with userequirements in mind. The different portionsof each culm should be classified accordingto their dominant characteristics, and theculms should be cut up on this basis. Thevarious cuts should be segregated intogroups according to the purposes for whichthey are best suited. Zigzag or curvedculms may be used for purposes where shapeis unimportant, or where they may give anartistic effect. Special processing, such as

dressing o f f nodes of whole culms, maypermit closer fitting. Culms may be splitto make boards or lathlike strips. Finally.the design of the structure and its archi-tectural details may be modified to a cer-tain extent to utilize more effectively thenature and peculiarities of the building ma-terial.Extreme Fis sibility

With the exception of thick-walled bam-boos such as Bambusa tolda and Dendrocal-amus strictus, or those- relatively softwood, such as certain species of Guadua,bamboos have a tendency to split easily, atendency that precludes the use of nails. Italso limits the range of techniques suitablefor the framing or joining of structural units.

Suggested remedies are to use the lesseasily split culms of thick-walled speciesfor purposes where high fissibility is a dis-advantage; to make end cuts just beyond anode where feasible (the nodes have a highershear coefficient than the internodes andhence show less tendency to split); to fastenjoints by means of thongs or other lashingmaterials; to chi> ~1 o r bo r e holes to accom-modate nails, screws, or pegs.Low Durability

Some bamboas are highly susceptible toinvasion and partial destruction by wood-eating insects, such as termites and powderpost beetles. Species with relatively lowsusceptibility may be selected; and the culmsmay be treated to make them less vulnerable.Cut surfaces at the ends of the culms a r eplaces where insects usually effect an entranceand should be treated with special care.

Most bamboos also show high suscepti-bility to rot fungi, especially under damp con-ditions and in contact with moist soil. Hereagain, selection of species will help to over-come the weakness, but some form of preser-vative treatment should be used to prolongthe usefulness of bamboos expos,ed to moistsoil.

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Walter Liese BambooMethods of Treatmentand Preservation

In all its many fields of utilization bambooIs exposed to attack by microorganismsandnsects. The service life of the struc-tures therefore is mainly determined by therate of attack.

I. Sewice life ot bambooBamboo is liable to attack by fungi (brownrot, white ret. soft rot) and especially byInsects (beetle5. termites). Its durabilitydepends mainly on the climatic conditionsand the environmenr. In general it has beenfound that untreated bamboo has an aver-age life of less than l-3 years where it isexposed to atmosphere and soil. Undercover, however, 4 -7 years or more may beexpected depending on the nature of useand the conditions. llnder favorable circum.stance5 bamboo has been in service asrafters or frames for more thanTO-15 years. In sea wato it is destroyedby marine organisms In less than one year.Genc:ally speaking, bamboo has a lownatural resistance compared with wood.Most of the observations on its durability

The lack of a preservative treatment forbamboo in spite of its widespread utilisa-tlon can be related to the followingfactors:1. Lack of knowledge about possibilities ofbamboo protection.2. Lack of facilities, both regarding treat-ment facilitlss and preservative cheml-cals.3. Uncertainty about the advantages ofbamboo preservation.4. No marketing of treated bamboo.For any consideration of bamboo preserva-tion a knowledge of the available methods,their advantages and disadvantages isnecessary. The methods applied in theAsian countries with bamboo resourceshave therefore been compiled, and a surveyis given in the following, Since anyefficient treatment depends on the penetra-bility of he material, the treatability ofbamboo has to be discussed first.Ii. Treatability of bambooThe treatability of bamboo is in genera)are based on estimations made on full-sized structures. Special service tests have rather low. It differs according to species,1hardly baen carried out so far. Results from age and moisture content of the culm.graveyard tests are still rare. : treatment method and type of preservative.1 Most of these factors are influenced by the

durability in the culm itself, it was observedthat the bottom part has, on average, ahigher durability than the middle and topportion. The inner part of the culm is fasterattacked than the outer one. because of itsanatomical structure. Laboratory experi.ments under controlled conditions haverevealed that bamboo deteriorates morerapidly when attacked by white rot and soft

Split bamboo is more rapidly destroyed

rot fungi than by brown rotters.Deterioration of bamboo by powder post

than round bamboo. A5 regards the natural

beetles starts as soon as the culm isfelled. This attack can be attributed to thepresence of starch, and for the speciesDinoderus minutus the deterioration wasfound to be proportional to the starch-content. According to some ir,vestigationsbambcos harvested during summer aremore rapidly destroyed than those felledafter the rain period. Flowered bamboo,where starch has been depleted, has ahigher resistance to beetles, but it appearsto be brittle.

by the following characteristics, whichare important for the penetration of pre.servatives:

anatomical structure. A bamboo culm can: be differentiated anatomically from wood

1. The vessels run strongly axial. They areisolated from each other by theparenchyma in the internodes andconnected only in the nodes: they arevery small at the periphery of the walland become larger near the centre.2. A special layer of cells covers the walloutside and inslde and retards penetra-tion from both,sides.3. There are no ray cells in the bambootissue - these are essential for an easymovement of liquids in a radial direc-tion.The penetration of liquid Into a culm takesplace preferentially in the axial directionfrom both ends through the vessels. To asmall extent movement is also possiblethrough the intercellular cavity and thesieve tubes of the vascular bunales.. Somepenetratlon occurs at the nodes where thebranches are cut off. The penetrationthrough the cuticula is slow and needs arather long time. However, from the innerside diffusion Is better than from tha Outerside. In the living culm the cuticula DrO-vides protection against water less in theculm and it is obvious that there also Its alow rate of diffusion in or.& :issue. Even

The natural durability of bamboo variesaccording to species; for example Dendro-ealasmus strictus is less resistant totemrltes than Dendrocalamus longispathus.Because of its low natural durability apreservative treatment is generally regardednecessary. However, such bamboo treat-ment has seldom been carried out.gate 1181

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rnder pressure Ve lateral penetration isrery small.t has been recommended thatby incisingthe Inner part of the wall additionalopenings for penetratlon may be obtained.But the structure of bamboo is such that abetter treatability by this method could onlybe obtained for shart lengths. In anothertrial, attempts are made to bore axiallythrough the normally Impermeable dia-phragm of the nodes, so that the culm actslike a vessel for the presarvative and theliquid can penetrate easier from the insidewall. In this case it must be ensured thatthe preservative is removed from the insideof the culm after treatment, otherwise it willbe last, and furthermore wrong absorptionvalues will be obtained.For a satisfactory treatment of the tissue itis necessary that the preservative diffusesfrom the vessels into the surrounding fibresand parenchyma cells. The vessels occupyonly a small portion - about 5-10% - ofthe cross-section. Even when the vesselsare completely filled the bamboo culm canbe destroyed by fungi or insects if thepreservative does not diffuse into thetissue enough and the maln portion of theculm is thus left untreated. Consequentlyfor the treatment of bamboo, only preserva-tives which have good diffusion propertiesshould be used.

III. Methods for the protectionof bambooThere are two kinds of methods which maybe used to increase the durability ofbamboo: non-chemical methods, in whichpreservatives are not involved, and chemi-cal methods. Whereas nonchemicalmethods have been used for a long time inthe villages of many countries. chemicaltreatment on a larger scale is appliedmainly in India and Taiwan. In Japan,prophylactic treatment and surface protec-tion during processing is common.1. Non.chemlcal methodsThese are generally the so-called tradi-tional methods, which are used quiteoften, though not much is known abouttheir real effectiveness. However, they costalmost nothing and can be carried out bythe villagers themselves without specialequipment.Curing: Culms are cut at the bottom, butleft for some time with branches and leaveson the clump (clumpcuring). Transpirationof the leaves still continues, and so thestarch content in the culm is reduced. A5 aresult, the resistance to infestation byborers is said to be Increased, but there is

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no influence on the resistance to attack bytermites or fungi.Smoking: The culms are stored above fire-places inside houses for some time, so thatthe ascending smoke causes a blackeningof the culm. It is possible that toxic agentsare produced which lead to some re-sistance. Due to the heating, the starchwithin the parenchyma cells may bedestroyed too. In Japan, bamboo material iskept in heating chambers at 120-150 Cfor 20 min., which is considered to be insome way effective against insect attack.Cracks can occur, however. which lead toeasier attack later.Whitewashing: Bamboo culms and bamboomats for housing construction ar? oftenpainted with slaked lime (Ca(OH),). This isdone largely because of the ornamentaleffect of the white colour. although as aside effect a prolongation of service life isexpected. It seems possible that the waterabsorption is delayed by this treatment,leading to a higher resistance to fungi. butspecial investigations have still to becarned out. The strength of bamboo may beaffected by such an alkaline treatment.In Indonesia, bamboo mats are tarred andlater sprinkled with fine sand. As soon asthe sand clings onto the mat and the tar isdry, up to four coats of whitewash areapplied. Plastering. too, is commonlypraclised by the people, with cow-dungmixed either with lime or with mortar.Soaking: This method is commonly used InAsian countries. The freshly cut culms areput into stagnant or running nater or mudfor a period of several weeks. Since thespecific gravity of the culms is less than 1,stones have to be put on the bamboos tokeep them under water. Subsequently thebamboo is dried for some days in a shadyplace.During the soaking period the starchcontent of the parenchyma cells - im-portant for the attack by borers - isreduced. The method is therefore said toimprove the resistance to borers. Thisassumption. however, has yet lo be proved.It must also be emphasized that themethod, on the other hand, does not in-crease the resistance to termites andfungi. Submergence in water may also leadto a staining effect on the bamboo.Constructional methods: Much damage canbe avoided by placing bamboo posts onstones or on cement walls instead ofputting them directly into the ground. Bymeans of such constructional methods thebamboo material can be kept dry, so that atleast deterioration by fungi may beprevented. It is strongly recommended thatin a bamboo house the basement should bemade of concrete work or stones. Treat-ment with water repellent formulae reducesthe hygroscopic properties, with the effectthat mouids are kept off.

2. Chsmlcol methodsMethods using chemicals for preservationare generally more effective for the protec-tion of bamboo than non-chemicalmethods, but they are not in everycaseeconomical and applicable.to

Fumigation: Fumigation Is applied in Japanfor insect control by using methyl bromideor other chemicals.Brushing and spraying: Brushing and spray.ing of bamboo are rarely earned out otherhan for prophylactic purposes. Thesemethods have only a temporary effectbecause of the very low penetration of thepreservatives. Both can be applied toprevent borer and moulds attacks.A prophylactic treatment may be advisablein bamboo depots and paper mills . In thefight against the bamboo borer Dinoderusminutus a 5% solution of DDT, 0,5%Gamma-BHC or 05% Dieldrin proved to beeffective, if permissible.Bamboo piles, which are placed in theground, are sometimes tarred and after-wards wrapped in palm fibre ropes.Butt treatment: The bottom sections offreshly cut bamboo culmswith branchesand leaves are placed in a barrel containingthe preservative. The transpiration of theleaves, which is still in progress, draws withIt the solution into the vessels of the culm.After cutting and subsequent handling,however, air often gets into the vessels althe bottom, thus neutralizing the suctioneffect of transpiration. Moreover, thismethod is possible only with rather shortculms with high moisture content. It takesa long time, and in most cases the vesselsdo not take up enough liquid to preservethe surrounding fibres and parenchymaceils sufficiently by later diffusion.Open-tank method: The open-tank treat-ment is an economical and simple methodwith a good protective effect. Culms cut tosize are soaked in a solution of a water-soluble preservative fo: several days, Thesolution gets into the culm by diffusionthrough the ends and partly through thesides. Practical investigations carried outon the conditions for open-tank treatmentlead to the following results: Immaturebamboo shows evidence of much betterpenetration both through he outer and theinner skin than mature bamboo. This effectmay be correlated wilh the amount oflignificalion. Both the outer and the innerskins are permeable to some extent topreservatives during longer soaking; theinner skin, however. is a little morepermeable than the outer one. Conse-quently, split culms can be treated moreeasily than round ones. By using splitbamboo, the soaking period would bereduced by 113-112. Penetration andabsorption of wafer-soluble preservativesare lower in freshly felled culms than inair-dry material.In air-dry culms diffusion in the axial direc-tion was found to be about 20 limes greaterthan in the transverse direction; radialdiffusion is slightly more than the tan-gential. In the inner part of the wall it isfaster than in the outer part. The treatingsolution should be of a higher concentra-tion when green bamboos are used. Sincewater absorption in bamboo is generallyslower than in treatable wood species, thesoaking period has to be considerablylonger than that for wood of the samedimensions.

Summarizing it can be stated that bambooin round and split condition can beSatisfactonly preserved .by soaking. Theduration of treatment depends mainly onthe kind of preservative chosen, on thebamboo species and the condition or thgculm (Liese 1959, Singh et al. 1965).BY Using hot dipping or the hot and coldmethod the time of treatment can beconsiderably reduced. Mechanical scratch-ing of the outer skin could speed up thepenetration, expecially for slow diffusingpreservatives.Boucherie.method: The boucherie methodis an effective method if the material to bepreserved is available in the green condl.tion. The water-transporting part of theculm can be penetrated completely and thetreatment itself involves little - andinexpensive - equipment. In its classicalform the preservative is forced by gravityfrom a container placed higher than thestem through pipes into its base end. Thehigher the vessel is fixed, the faster thepenetration. It is also possible to hang theculm vertically, and to scratch the innerwall of the top internode in order to use itas reservoir for treatment. The internodehas to be filled up several times.At the beginning of the boucherie treatmentthe solution, dripping from the top end,consists mainly of sap and has to beremoved. Later on the solution can becollected and, after the addition of newsalts, it may be used again. The treatmentis finished when the solution at thedripping end shows a sufficiently highconcentration of chemicals.This method has been improved by applica-tion of pneumatic pressure (air pump) overthe preservative fluid in a reservoir(A. Purushotham et al. 1953). At the bottomof a container a small metal tube is fixedfrom which several other tubes leading tothe ends of bamboo culms are led off.The culms are fastened to the tubes byrubber sheaths. The preservative is forcedaxially through the culm by the air pressurein the container. Compared with the classl-cal boucherie method, the time of treatmentcan be reduced from several days to3-S hours. Such boucherie installationsare easy to transport and could be used directly in the forest.The duration of treatment and the effectiveness of this method depend mainly on thebamboo species. the moisture content ofthe culm and the preservative ussd. A lowinitial moisture content results in ahigher osmotic pressure of the parenchymacells surrounding the vessels. Thus thewater is withdrawn from the preservativesolution inside the vessels, so that precipi-tation occurs, blocking the vessels. Thebest results of the boucherie method aretherefore obtained during the rainy seasonor after it; failures may occur during the dryseason. Young, immature culms with ahigh water content are more suitable fortreatment than mature ones with lowmoisture content. The kind of preservative,and in particular its precfpitation. adhesionand swelling influences on the ceil wall, isalso of great importance for successfultreatment. Preservatives with a high rate of

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precipitation and adhesion generally stopflowing through the culm in a relalivelyshort time, so that the vessels and pitsbecome blocked.Altogether it can be slated that the periodof treatment is considerably reduced bythis method compared with the classicalboucherie method, thus leading to a more

preservation plants the cost of treatment isadditionally increased through trar,sport ofthe bamboo material from the forest to theplant. Instructions to the consumers areregarded as necessary, since they have tobe advised that higher initial expenses wil lpay off by a much ;onger service life oftreated material. One must also tnke into, consideration the replacement costs, whicheconomical preservation. Relatively simplehandling and reasonable installation costs I often amount to much more than the costmake this method sui table for many : of the materlai ttse,,Ipurposes. The cost of treated culmscompared with the cheap untreated culmsrestricts its use for certain fields ofutilization. It is also not applicable for allbarnboo species, e.g. aambusa arundina-tea, which has thin walls, splits easily andis thorny.Pressure treatment: Pressure treatment ofbamboo is carried out in some countries,both with water based preservatives andwith creosote. However, it is expensive andIn most ca:;es not economical for cheapmalerlals like bamboo. Neither are thereenough plants available for ths manu-facture of preservatives.For pressure treatment the material shouldbe air dry to ensure sufficient penetration.During treatment of bamboo in round form,cracks and collapse may occur. Thisreduces not only the strength of the culmbut leads also to inaccurate results whenmeasuring the amount of absorbed pre-servative. Cracks and collapse ariseespecially in thin-walled bamboos. so thatonly thick.walled specres should be treatedin round condition. Generally, in roundculms, the preservative solution penetratesmainly from the cut surfaces and nodesInto the cuim, but less through thecuticuia. Split bamboos show a muchhigher absorption and penetration than

Fire-proofing bamboo could reduce thegreat losses due to fire hazards, whichspread fast over large areas. However, thecost for such treatment would be muchhigher than for protection against insectsand fungi. Therefore, at the present, fireProtection is not regarded as of im,mediateImportance.

IV. Conclusions and recommendationsfor research on bamboo treatment1. Economical points of viewBamboo is abundantly available in Asia andwidely used as constructional materfat. Inspite of its many excellent properties,bamboo is liable to biological deterioration.Although the culms are reasonably cheap,the repair or the need for re-construction ofa bamboo house is a big item for thecommon man. Therefore the prolongationof the service life of bamboo houses andother bamboo-constructions as well as theprevention of decay durmg storage are ofgreat importance for the peoples economy.Any preservation of bamboo must be tcheap, easy to perform and readily avan-able.

different bamboo species, age classes andmoisture content, is also necessary.

4. PreservativeFor any chemical protection only a suitablepreservative in a sufficient concentrationmust be applied. The use of a wrong typeof preservative or a low concentration willlead to failure and to mistrust of chemicalpreservation of bamboo or timber. Forbamboo, water soluble preservatives are tobe recommended. If treated bamboo is tobe used in the open, non-leachable pre-servatives are called for. As far as possiblethe preservative should not containcomponents poisonous to human beingsand animals, since in tropical countries it isdifficult to observe always the necessaryhygienic precautions during treatment.

5. introduction al bamboopreservationThe introduction of bamboo preservation isa rather difficul t task. The consumer willhesitate to pay more for a raw materialwhich has been treated, If he does notknow i ts advantages. Since rhe preservationof bamboo, especially for houses, wouldstrengthen the economy of the commonman, the Government authorities muststrongly support the Initiation of bambootreatment.

i The following steps are recommended:/ a) Placing of treated and untreated bambooI samples in front of every Forest Dist rict-,/ Ranger- and Beat-Office. After a snort time

the villagers will be forced to notice thegreat advantages of treated materfal. Thesamples should be supplied from oneround bamboo. Here the preservative can

IInstitution, where treatment has been pro-

penetrate from the sides too, thus render- / 2. Constructional methods perly conducted.ing the treatment effective. In both cases. 1 b) lnstallatlon of open tank bassins at thehowever, it is necessary that the preserra- More attention should be given to Improve. ment of house construction techniques. In rangers or beat offices, so that treatmentis controlled by the Forest Service.several cases constructional methods can 2reduce the hazard of attack. The fungal : c) Supply of the preservative free ofdeterioration of the bottom sections of 1 charge, either through the Forest Service,i bamboo posts in particular can be pre. / the Agriculture Development Corporation or; vented by placing them on stone or cement 1 the Forest Industries Development Corpora-

tive has the potential to diffuse into thetissue later.

III. Economics of bamboo preservationSo far not much is known regarding theservice life of treated bamboo: the availableresults havebeen obtained from field testsand less from full-sized structure. Reliabledata depend on numerous factors like themethod of treatment. kind of preservative,absorption and penetration as well as onthe specific condition. In order to makea treatment economical the service life oftreated bamboo compared with untreatedmaterial should be lo-15 years in theopen and 15-25 years under cover.

basements instead of putting them directlyinto the ground.tlonas a Government contribution to thepeoples welfare.

3. Treatment methodsThe benefit of protection by nonchemicalmethods is still doubtful. It is thereforerecommended that more information abouttheir effectiveness be collected and specialtests be performed. As regards chemica lmethods, only simple ones are to beconsidered. Most of the villages are farfrom industrial centres, where technicalinstallations could be carried our withoutdifficulty. For the treatment of bambooposts, mats, and tarjas the open tankmethod is recommended. it does not need

d) The consumer should treat his ownmaterial and should be charged only anominal fee per piece. if real costs were tobe charged, no bamboo preservation couldever be started in the villages; this wouldconsequently lead to a vast amount ofdestruction of bamboo houses year afteryear. Such losses, taking place here andthere, would weaken the nations economyin the long run.Similarly there is very little informationavailable on the economy of bamboo pre-servation. Inasmuch as bamboo is a cheapand easily available raw material, itspreservation must also be inexpensive.In some cases, therefore, physical methodslike soaking in water are in use - methodswhich can give only temporary protection.The open tank treatment is recommendedas the most economical method. in certainspecial cases one might also practise themore expensive methods like pressuretreatment. Due to the small number of

gate l/81

e) An action group for the introduction ofbamboo preservation should be establishedwith the following programme set-up:1. Collection of information of servicelife of bamboo structurescomplicated technlcal installations and can 2. installation of untreated and treatedbe used in ail places of demand. Forbamboo culms the butt treatment is also ; samplesadvisable. Special research on the duration 1 3. Elaboration of the treatment procedureof treatment for obtaining sufficient re. 1 4. installation of open tank bassins

tention and penetration with the available , 5. inspection of the treatment workpreservatives, taking into consideration the 6. Marketing of treated bamboo. m

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C. C.C.A. SOAK OF BAMBOOThis method is for preserving woven bamboo that is going to be in Wet Use.--.That is, it will be on the outside of a building. If you are preserving- bamboo for inside a house, you should use the Octabor Diffusion of,Bamboo.It is simpler, cheaper method and will do a good job inside a house.It is important when treating bamboo, to split it before treating it.Bamboo has a waxy coat on the outsi.de nd the preservative cannot go througthis. When you split the bamboo, the preservative can soak into the woodfrom the inside. Remember this and do not try to treat the whole piece ofbamboo.Materials: Here is a list of the things you will need to get before youcan treat bamboo.C.C.A. Salts - This comes in 9.1 kg (20 lb) packages. One of these shouldmake enough preservative to treat the bamboo needed to make a wall 15metres (50ft) long by 3 metres (lOf$) wide. You must decide how much tobuy.Soaking Trough - You will need a trough about 4 metres (13ft) long and bigenough to hold plenty of bamboo. You cdn make a good trough by cutting 2,200 litre (44 gal) drums in half lengthways and welding them together likea canoe as shown in the picture. You can cut the drums with a cold chiseland hammer, or with an axe. After you have cut the drums, you shouldflatten the edges with a hammer so that they are not so sharp.

Putting Stones on the Bamboo to Hold it Under the PreservativeAfter you have welded the drums together, it is a good idea to paint theinside with tar or bitumen. If you do not do this, the preservative willmake the drum rust very quickly.AMixing Drum - You will need a drum that can hold at least 180 litres (40gal) of water. A 200 litre (44 gal) drum will do quite well. Put a markon the side 760 mm (31") up from the bottom. When the drum is filled

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to there, it will have 180 litres (40 gal) in it. You can also use a18 litre (4 gal) drum to measure 180 litres (40 gal) into the drum and markit that way.Rubber Gloves - The C.C.A. Salts are very poisonous. Whenever you aretouching the preservative, or bamboo that is still wet with preservative,you must wear these.A Plastic Bucket - You will need a bucket to get the preservative from themixing drum into the trough. One that holds 6 to 9 litres (l# gal to 2 gal)will do very well.INSTRUCTIONS:Now you are ready to start. Please follow our instructions carefully.Prepare the Chemical Preservative - Put about 140 litres (30 gal) of waterin the mixing drum. Mix in one, -9.1 kg (20 lb) bag of C.C.A. preservat-ive and stir until dissolved, add enough water to fill the drum up to 180litre (40 gal)" ark.This gives you a 5% solution. That is , 10 litres contains 3 kilogram(1 gallon contains 4 lb) of preservative. For treatment of the bamboo,this concentrated preservative will be diluted with water to give a 235%solution, containing 23 kilograms of preservative in 100 litres (2% lbin 10 gallons).Split the Bamboo - As we said before8 the bamboo must be split open beforeyou treat it. You can do this in whatever way you usually do. Afterit is split, you may find it easier to handle if you tie the split bamboointo bundles before you treat it.Fill the Trough - Put the bamboo into the trough. Only put enough in sothat when you fill the trough up, all the bamboo will be completelycovered with preservative. On top of the bamboo, put scme big stones sothat the bamboo does not float up.Now you must fill the trough up until the bamboo is all covered. Becausethe preservative you have mixed is concentrated, you must dilute it. Soput one bucket of preservative into the trough and then add one bucket ofwater. Put another bucket of preservative and another bucket of water.Keep doing this until the hatzboo s covered.Wait 1 Week - The bamboo must soak for at least seven days, so that thepreservative can soak in. During this time, you should cover the troughwith plastic. This will keep the rain out and stop children or animalsfrom poisoning themselves, with the preservative.Remove the Bamboo - After 1 week or more, lift the bundles of bamboo uponto sticks laid across the trough and let them drain into the trough. Bydoing this you do not waste any preservative. After it has drained fora few hours, the bamboo should be set out to dry for a week or more. Itis best to do this on a rack set up off the ground.After the bamboo is dry, you can sue it in your house.

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FIGURE 12

Bamboo Draining Over Trough After SoakingThere will always be bits and pieces of bamboo left over when you havefinished weaving it. Do NOT burn these scraps. Bury them in the groundfar away from wells and streams. A pit latrine is a good place to burythem.D. Octabor DIFFUSION OF BAMBOOThis method is for preserving woven bamboo that is going to be in Dry Use,that is, it will not get wet. Bamboo for inside walls or for the insidelining of outside walls, can be treated this way. Bamboo that has beentreated by Octabor Diffusion, can also be used on the outside of buildings,IF it is painted. If you want to use bamboo on the outside of buildingsand are not going to paint it, the walls should be protected from therain by wide eaves.This method is almost the same as the C.C.A. soak. The biggest differenceis that we use a different preservative. Octabor is much less expensiveand not as poisonous as C.C.A.You can put Octabor preservative into the bamboo by one or two ways.You can soak the bamboo in a trough of preservative. This is a goodmethod, but you need a trough. The trough is the same as the soakingtrough in C.C.A. Soak of Split Bamboo.The other way is to paint the preservative on and let it soak into thebamboo. This is more work, but you do not need to make a big trough. Theend result of both ways is much the same.If you are only treating a little bit of bamboo, then painting is easier.If you are doing a lot, then it is worthwhile making a trough.

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Materials: Here is a list of things that you will need before you cantreat the bamboo.Octabor Preservative - This comes in packages of 3.6 kg (8 lb). Eachpackage is enough to treat about 500 lengths of 4 metre (12ft) long by 50mm (2") diameter pieces of bamboo. If you are using a trough, you willneed some extra, because some will be left in the bottom of the trough.You must decide how many packages you will need to buy.ASmall Drum or Can - You will be mixing up 18 litres (4 gal) of preservativeat one time. A drum or a can that will hold #is much or a little moreis just right. The drum must not leak and should not be rusty.Soaking Trough - If you are going to use a trough, then you will need tohave one made. Read the instructions about this under C.C.A. Soak ofBamboo on Pages 48 and 49.If you are going to paint the Octabor on, then you will need:-Plastic Sheet - This will be used to wrap up the pile of bamboo during.treatment. Because of this:.you ill need a big piece, big enough to com-pletely cover the bamboo on top , underneath and on all sides. A piece1.5 x 10 m (8ft x 30ft) should be enough.Paint Brush - This .is or painting the preservative onto the bamboo. YOUwill want a brush about 100 mm (4") wide.Water - However you put the preservative on, you will need plenty of Water,for mixing the preservative and for washing afterwards.When you have all these things, you will be ready to start. Please followour instructions carefully.INSTRUCTIONS:Prepare the Chemical Preservative - on the side of your mixing drum, puta mark about where you think 14 litres (3 gal) of water comes to andanother mark for 18-litres (4 gal). Then fill the drum up to the lowermark with hot water. You can build a fire under the drum if you like.Now put inxe package of Octabor, 3.6 kg (8 .lb) nd stir until it isall dissolved. Finally add enough hot water to fill the drum up to the18 litres (4 gal) mark. This solution now contains 2 kg per 10 litres(2 lb per gallon). This is a 20% solution.Prepare the Bamboo - The bamboo should still be green when you treat it.Cut the bamboo, bring it to where you are working, split it and prepareit as quickly as possible. Do not start cutting the bamboo until you haveeverything eise ready.Using the Soaking Trough - This is exactly the same as the C.C.A. Soak,except using Octabor instead of C.C.A. You should read the section onC.C.A. SO& of bamboo as well.Fill the Trough - Put the bundles of bamboo into the trough. Only putenough in so when you fill the trough up, all of the bamboo will becompletely- ----covered with preservative. On the top of the bamboo, putsome big stones XI that the bamboo does not float up.Now fill the trough up until the bamboo is all covered. Because thepreservative you have mixed is concentrated you must dilute it. SO putone bucket of preservative into the trough and then add three buckets Of\water. -15-


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Put another bucket of preservative and another three buckets of water.Keep doing this until the bamboo is covered.Wait 1 Week - The bamboo must soak for at least seven days, so that thepreservative can soak in. During this time you should cover the troughwith plastic, this will keep the rain out and stop children and animalsfrom poisoning themselves with the preservative.Remove the Bamboo - After one week, lift the bamboo bundles up onto stickslaid across the trough and let them drain into the trough. See how thisis done by looking at the photo in the section on C.C.A. soak of bamboo.By doing this, yo.u o nut waste any preservative. After it has drainedfor a few hours, the bamboo can be used straight away. The Octabor treatedbamboo should be kept in a dry place under cover at all times.It is important not to let this bambcro et wet. If it does, the water willwash out the preservative and your work and money may be wasted.Painting the Octabor onto the Bamboo - Spread out the plastic on the groundand put a layer of bamboo onto it. The bamboo must be laid with the insideupwards. Paint the bamboo with the 20% solution of Octabor you have made.Spread another layer of bamboo the same way, inside up. Paint it alsowith Octabor.Keep spreading layers of bamboo and painting it with preservative untilall the bamboo is on the pile. If this takes more than one day, cover thepile with plastic overnight.Finally, when you have painted them all, and they are all piled up, coverthe pile with sheets of plastic.Put stones or pieces of wocd all around the edge so that no air can getinto the pile.Wait 2 Days - After the two days are over, remove the plastic. ThebambooY--is now ready to use. It does not have to be dried, but should be keptunder cover, out of the rain.It is important not to get this bamboo wet. If it does, the water willwash out the preservative and all your work and money may be wasted.Wasted Bamboo - There will always be bits and pieces of bamboo left overwhen you have finished weaving it. Do NOT burn these scraps. Bury themin the ground far away from wells and streams. A pit latrine is a goodplace for the scraps.E. THE USE OF WATER REPELLANT PRESERVATIVE (W.R.P.)W.R.P.'s are specially prepared mixtures of a fungicide, resin and wax inan organic solvent. When dry timber is dipped in a W.R.P. or the W.R.P.is painted on the cut end of a piece of timber, it is sucked into the timberfor a short distance. The solvent evaporates, leaving the fungicide, waxand resin behind. If you can do it, dipping the wood for about threeminutes is better than painting the W.R.P. on.The wax and resin help to seal the pores in the wood and stop water fromsoaking into the wood. The fungicide will prevent rot starting in thecut end where the W.R.P. was applied.

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"Antidotes" for Wood PreservativesC.C.A. : C.C.A. has a very bad taste and wili burn the mouth ifsomecne tries tc drink some. It is very poisonous and ifsomeone drinks some C.C.A. preservative, they will die,unless they receive immediate medical attention.

If someone does drink some C.C.A. or Octabor preservative,first make them drink lots of water and then encouragethem to throw up (vomit) by placing your fingers downtheir throat. Then make them drink more water and throwup again. Do this at least three times. If you havemilk, use this milk instead of water. (If the person doesnot vomit easily, then do not waste time, but start movingto the hospital, try to make them vomit some more).Take some of the preservative and this booklet with youto the hospital so that the doctor will know exactlywhat has happened.If someone drinks some preservative and gets immediateattention from a doctor, he will probably be all right.

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1.4mAnuex III

End UEe of bEsIbConcentra-tion ofpreaerva-tive(percentage 1

Loading ofary chani-cal inb6mboobi# 1

mcteaProposed servicetreatment life(yesrs 1

Use in the open and la contactwith the ground (e.g., posts,pale-fencing etc.)a . . . . . . 80 to 128 Open tank orpressure process 15

6 to 8 8 to K Pressure procese6 to 8 5 to 8 Modified boucheriefor 6 to (2)8 hours or

steeping for 35 to40 aayE. . . 48 to 80 Hot dipDing oropen t a n l c o rprwmure process

15

bandc . . .. . . b andc

a . . .sa in tha open but not incontact with the ground(e.g., bridges, scaff+ol~ng~,lsdders etc.)bandc . . . 5 5 to 8

bandc 5 to 6 5 to 8Reesure proceselgyie&l l&l=07 steeping for20 to 25 days

Use under coyer:(a) Housebuilding, walls,tnmses, purlins,

rafters, tent polesetc.a (1) l a0 . . . 32 t0 40 Hot dipping or 20 to 30open tanh orpreeaure process

bandc . . . 4 4d, e and f . . . 6 8

b and c 4 4

Pressure processI,

knlified boucherie 20 to 30for 4 hours orsteeping for 15 to20 deysd,eandf

bandc .a.d, e, f, g . . .and h

b and cd, e, fand g

(b) Screens, ceil ings,doorsanddoorwelling, furnifureetc.

Pressure processII 1010Modified boucherle 10for 2 to 3 hours orsteeping for 8 to12 sassDipping for5 minutesRopl@actic treatment:green bsshoos includingsplints and round bamboosfor eventual full-fledgedtreatment after ar dryng

i andj . . . . . . . .

il lhe letters in these colons refer to the entries in the following list of preserostives.(1) Warning: bad smell(2) This is Boucherie plus air-pump on the drum.

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22/165

Chapter .: Housing2.1. -PartsofaHousefarwhichBan&oosare

suitable.MCCLURE, ages 2...5

2.2. - Use of B&co for Hutting, ilitaryEngineer, ol. 7, s. 48, (1950) p. 45-48

2.3. -Experiencewithroofsandtrusses inTanzania,bythelateJ?renkA.Bxilt~

2.4. - Hut Construction2.5. -Technicalinfomationonhouse improvemnt

for the purpose f controlling he plague2.6. - Building ith Bamboo, y D. Castro2.7. -Dmrsandwinduws2.8. - Tools

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p. 23

p. 27p. 30p. 31

34p. 63p. 70p. 72


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21 5 W start his chapter witha surtlmarybywluretitled:Parts of a House for Which Bamboos Are Suitable

Bamboo may be used alone to make allparts of a house except the fireplace and thechimney. Under most conditions, however,bamboo is actually combined with otherbuilding materials, such as wood, Clay, lime,cement, galvanized iron, and palm leaves,according to their relative suitability, avpil-ability, and cost.

The use of bamboo either as a primary,seaondary, or occasional eource of buildingmaterial is common only in areas wheresuitable bamboos grow in sufficient abund-ance. Importance of bamboo in any givenarea usually is determined chiefly by theeconomic level of the common people andby the cost of other, more durable, materi-als, Structural soundness adequate to theexigencies of local conditions is commonlyachieved with bamboo, but a Seneral manot-ony of design and a mediocre level of exe-cution characterize bamboo houses in manyareas. In certain cultural areas, however,and especially at higher economic levels,as among the well-to-do classes of Japan,Java, and Malaysia, bamboo is employedarchitecturally in ways that are distinctiveand basically artistic. Cohen indirectlyalludes to this recognition of bamboosspecial virtues: The principal post in aJapanese house characterizes the housewith regard to quality and construction.The roof members are trussed to the post,and enable a properly consfructed house tostand up to earthquakes and tremors. Thewriter has seen many houses in which theprincipal post is of stout bamboo, or inwhich a stout timber post is given morecharacter by being faced with bamboo. 1/

It is my expectation that an architectwill presently appear who combines a su-

y W. E. Cohen. Utilization of Bambooin Japan, p. 1. Commonwealth of Australia,Scientific and Industrial Research Grgani-sation. South Melbourne, Australia. April1947.

perior knowledge of, and devotion to, theprinciples of functional design with anawareness of the possibilities of bambooas a building material of strength andbeauty. Being an artist as well as an ar-chitect, he will appreciate the aestheticqualities of bamboo and its versatility asthey have been demonstrated in each areawhere its use has been lifted to a high plane.Given the right inspiration, the opportunityto travel and to study the best examples ofthe use of bamboo in building construction,and the cooperation of persons who knowthe bamboos and the techniques of usingtbcm, he will be able to synthesize thebest features of bamboo with the technicalimprovements suggested by his Westernbackground in functional design-and soproduce for each cultural area a series ofdesigns and plans that will be a credit tothe architecture of our age.

Bamboo has several characteristicsthat make it a suitable and economicalbuilding material for house construction,as well as for the scaffolding (fi& 1) thatfacilitates such construction:

. 1. The natural units, or culms, asthey are called, are of a size and shapethat make handling, storing, and processingboth convenient and economical.

2. The culms have a characteristicphysical structure that Rives them a highstrength-weight ratio. They are round ornearly so in cross section, and usuallyhollow, with rigid cross wallsstrategicallyplaced to prevent collapse on bending.Within the culm walls the strong, hardtissues of high tensile strength are mosthighly concentrated near the surface. Inthis position they can function most effi-ciently. both in giving mechanical strengthand in forming a firm, resistant shell.

3. The substance and grain of bam-boo culms make them easy to divide byhand into shorter pieces (by sawing orchopping) or into narrow strips (by split-

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ting). No costly machines, only simpletools, are required.

4. The natural surface of most bam-boos is clean, hard, and smooth, with anattractive color when the culms are prop-erly matured and seasoned.

5. Bamboos have little waste, and nobark to remove.Foundation

Examples of the use of bamboo postsinstead of a conventional foundation forlow-cost houses may be seen in both hem-ispheres Unless they are treatedwith some effective fungicidal preservative ehowever, such pasts are not +%x&ted tolast more than two or three years on theaverage; or five years at most under un-usually favorable conditions. Althoughno experimental data are available, itseems reasonable to expect that the last-ing qualities of bamboo culms set in theground may ultimately be extended appre-iably by applying pentachlorophenol in anappropriate form (see section on preser-vation). Until reliable and economicaltreatments have been deve ,ped for pre-serving bamboo that is frequently wettedor is constantly in contact with damp earth,it is considered better to use some materialthat is more durable than untreated bam-boo for foundations-concrete, for example,or stone, brick, or some durable hardwood

When used as supporting post5 in low-cost houses, culms should have a fairlylarge diameter, thick walls, and node5(points at which transverse diaphragmsoccur) close together to give maximumresistance to bending. Where large bam-boos are not available, smaller bambooswith suitable structural characteristicsmay be bound together to make COmpOSitepillars.

FrameNext to the foundation and the roofcovering, the basic frame is the part ofa house most often made partly or whollyof materials other than bamboo. In manyregions, those who can afford the differ-ence In cost prefer to use some durabiehardwood for frames They do50 partly because hardwoods make stifferjoints and more rigid construction than

bamboo, partly because a greater preL-tige is generally attached to hardwocds,.and partly because certain hardwoodsare naturally much more resistant torot fungi and wood-eating insects thanuntreated bamboo.

There are certain circumstances,however, under which the superior resil-iency of a bamboo frame confers impor-tant advantages over a rigid construction.In regions where sh.arp earth tremors orquakes occur frequently, a bamboo-framedhouse may survive and remain service-able longer than any other type

In the selection of materials for theseveral types of structural elements, thecharacteristics of the bamboo should matchthe function to be performed. Only wholeculms are used for the principal parts ofa bamboo frame. The dimensions of thevarious structural elements, and theirspacing, are governed by the nature andimportance of the function they perform.Stiffness and ultimate strength are impor-tant in elements of the frame. To get rel-atively uniform diameters, and maximumthickness of wood wall f o r stiffness andstrength), the upper, highly tapered, rela-tively thin-welled portion of the culms isremoved. These tip cuts may be used inwattle-and-daub partitions, or for roofsheathing, where close spacing may makeup for the inferior properties of the indi-vidual units.

The individual structural elements thatcompose the frame of a conventional all-bamboo house correspond closely to thosefound in an all-timber frame: Corner posts,girders or plates, joists, studs, struts orbraces, tie beams, king posts, purlins,ridgepoles, rafters, sheathing, and so forth.The use of bamboo imposes certain limita-tions , however. Mortice and tenon jointscannot be used in framing bamboo: any cu t ,such as notch OP mortice, drastically re-duces the ultimate strength of a bambooculm. The only exception is the notch orsaddlelike cut used at the upper end of poststo cradle more securely the horizontal ele-ments that rest upon them (fig. 6, C and D).

With the exception of those of certainspecies of Guadua (notably G. angustifolia)and of Chusquea, the culmsof most bambooswill not take nails without splitting. Forthis reason, the impinging elements are

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"figs. and 7, see pages 134 and 135"

generally lashed to each other at their in-tersections (figs. 6 and 7). In the Far Eastthe withes used for lashings are commonlysplit from bamboo, more rarely from rattan.Where the ava.ilable bamboos yield brittlewithes, t.ough vines or the bark of certaint.rees and shrubs may be used Lor la~5hfngS.In some areas, soft iron wire, most of itgalvanized, is used.

Common sense and the empirical knowl-edge of bamboo craftsmen in various coun-tries constitute the most highly recommendedguidance for the selection and use of avail-able material. However, a resourceful per-son of practical experience in building mayoften be able to suggest sound and useful mod-ifications of conventional procedures.Floors

Many bamboo houses have no floor otherthan the surface of the earth on which theyare built. This surface should be, and usu-ally is, raised somewhat by filling withearth, to prevent inundation by drainagewater; it may be compacted by pounding. Ifthe f i l l is made with clay, so much the better,for clay affards a relatively stable surface.The s.urface of a dirt floor may be mademore stable by paving it with bamboo boards.The soil should first be graded to providenatural drainage, but not compacted, beforethe bamboo boards are laid in place. Thesemay then be pounded with a tamper of suit-able design, to drive them into close contactwith the surface of the soil, which is com-pacted by the same operation,

In better houses, the floor is raisedabove the ground. This arrangement is morehygienic, and provides a sheltered space be-low the floor, which has many potential uses.In some areas this space is devoted to therearing of various domestic animals; else-where it may be used for the storage of toolsand farm equipment, or even farm produce.It may provide a welcome sheltered playspace for children in inclement weather.Serviceable and attractive raised floorsmay be made entirely of bamboo, given suit-able species and a sound structural design.The principal features in conventional designare the supporting beams (part of the basicframe) and the floor covering.

Bamboo cuims are more resilient thanconventional timbers, and the space betweensupports should be reduced accordingly.

Spacing specifications must be worked outlocally for the individual species of bambooand the size of culm used..

The floor covering may be made of smallwhole culms, s.tri.ps , or bamboo boards madeby opening and flattening out whele culms

When the floor consistsof bamboo boards, it is generally fasteneddown by the use of thin strips of bamboosecured to the supporting members bythongs, wire lashings, or small nails, accord-ing to local preference and the materialsavailable (fig. 6, B).Walls, Partitions, Ceilings

The construction of bamboo walls is sub-ject to infinite variation, depending on theztrength required (for resistance to naturalforces such as hurricanes and earthquakes),the protection desired from rain and ordinarywinds, and the need for light and ventilation.Either whole culms or longitudinal halvesmay be used, and they may be applied ineither horizontal or vertical array. Theyfunction more effectively, however, whenthey are vertical, and are more durable; forthey dry more quickly after rain,

A form of wall construction widely fa-vored in Latin America is called bajareque

-at lea.st in Ecuador. It is made bynailing or lashing bamboo strips or slenderculms, horizontally and at close intervals,to both sides of hardwood or, more rarely,bamboo posts. The space between the stripsis filled with mud alone or with mud andstones. During this operation, the bamboostrips are more or less completely coveredwith mud but in time they become exposedby weathering. This form of constructionis relatively massive, though less so thanwalls made of conventional stone, rammedearth, or adobe bricks.

Another form of wall construction, per-haps more widely used, is known in Peruand Chile as quincha. It is a sprung-stripconstruction, known as lath-and-plaster,wattle-and-daub, or stud-and-mudIn this form, the flexible strips are woventogether to provide a base to receive th.eplaster, which is applied to one side onlyor to both sides.

A more attractive but less substantialcovering may be made of bamboo boards

If these boards are expandedslightly, i.e., stretched laterally, as they

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are attached, they provide a suitable basefor plaster or stucco. Sometimes barbedwire is nailed to the surface to provide abetter bond for the stucco. When whitenedwith lime or painted with cement, this ex-terior is ver,y attractive

Partitions are commonly of the lightestconstruction, such as a thin matting sup-ported by a light framework cf bamboo pbles.In the Philippine Islands, and generally inthe Far East, where suitable bamboos areplentiful, the partitions and even the outerwalls of houses are commonly covered withmatting woven from thin strips split fromthe culms For this pur-pose, bamboos with thin-walled culms andtough wood, such as many species of the Se-nus Schizostachyum afford, are preferred.

The width of the splines, or thin bamboostrips, and the pattern of weave vary locallyand according to the desired quality of mat-ting (called sawale in the Philippine Islands).Material for=nS is sometimes preparedfrom the culms of thin-walled bamboos bysimply cracking the nodes and opening theculms out flat, in much the same way asboards are made

The ceiling may be covered with a close-ly placed series of small unsplit culms, orby a latticework composed of lathlike stripssplit from larger culms. Bamboo mattingis favored as a ceiling finish in many areas.In some places the ceiling is omitted alto-gether, permitting the freer circulation ofair welcome in hot, humid seasons. Thisomission has the added advantage of facil-itating the dispersal of smoke from thekitchen f i r e . In the areas where bamboo isused f o r housing, a chimney would be a cur-iosity.Doors and Windows

For practical reasons, window and out-side door openings are generally kept to aminimum. They may be framed with woodor bamboo. The doors themselves may bewood, or they may be woven bamboo mattingstretched on a bamboo frame, a panel ofbamboo boards set in a hardwood frame, ora sturdy Satelike barrier constructed ofbamboo bars. Boors are side-hinged, andfastenings vary from the traditional latch-string to lock-and-chain.

If window openings are provided, theymay be framed with bamboo or wood. Mostwindows ace left unglazed and unscreened.Closure ma:? be provided in the form of abamboo or wooden frame covered withbamboo mattiltS or palm-leaf thatch. Win-dows are usuaily hinged at the top; whenopen-as they are during most of the day-light hours-they serve to exclude the sunsdirect r ays or light rainfall. At dark thehouse is closed, to keep out the night air,generally considered unhealthful. Actually,the closing of houses at night is justifiableon other, more realistic, ground: it preventsthe entrance of mosquitoes, rats, bats, andother unwelcome visitors. Permanent win-dow bars of bamboo, many of them paintedblack to simulate iron bars, are frequently:*sed to frustrate would-be trespassers.Roof

Because of their high strength-weightratio, bamboos are used to excellent advan-tage for structvral elements in roof con-struction (fig. 6, A). In designing the roof,account must be taken of the nature andweight of the r o o f covering to be used,whether it be grass or palmleaf thatch,halved bamboo culms , bambooshingles, corrugated sheetmetal, eternite

or tile The dimensions, orentation, and spacing of Lhe individual struc-tural units that support the roof covering arvaried to conform to the requirements of thecase

-26-


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THE ERECTION OF A BAMBOO BUILDING..--A series photographs,

'1.Erection of bamboo poleframework, Poles aretied with native vines.

2. Preparation for erec-ting roof framework.

-7 ( *I 3. Fabricating walling>,a -:-_.-: :-- from split bamboo.

4. Tying walling to bam-boo frame.


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Li22 . USE OF BAMBOO FOR HUTTING 1)n From: Military Engineer, vol. VII, s. 48,1950, p: 45;48

1. Wherever bamboo is plentiful, serviceable hutting can beconstructed by using it for the framework and using localthatch or banana leaves for roofing and split bamboo for walling.2. In Assam and Burma the majority of the native buildings are

constructed of bamboo, the local inhabitants being expert in itsuse. The framework of the walls and roofs of huts can be made ofbamboo poles lashed together with local split cane or spun yarnor wire.For wall covering the bamboos are split and then beaten flat.They are used either in straight lengths or woven into panels.3. The male bamboo is found up to 3" (7.5 cm.) in dia. and is verystrong. The female bamboo, of which there are several kinds,varies in strength. It grows up to 6" (15 cm) in diameter.The stronger types of female bamboo are suitable for theframework of huts, but the weaker types are more suitable for

splitting and using for walling.4. For roofing, bamboo leaves or palm fronds make a good thatch.Banana leaves laid in layers at a good pitch provide a water-proof roofing for temporary work.5. The photographs on the pages 28 and 29 show the use of bambooin hut construction.

By courtesy of the Ministry of Defence, London, U.K.-27.t


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5. Placing bamboo polesto form the roofframe.

-. Framework completeand thatch cover be- Ping placed. tI

8. View of interior of 4partially completed * " 4tbuilding. ,..LI

9. The roof frame is co-vered with palm fronds

7. Placing end gable.


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23 m Experience with roofs and trusses in Tanzania.- by the late Frank A. Railton (volunteer)Faced with the problem of building large quantities of quarters forAfrican labourers, and bedevilled with the usual minimum amount ofmoney available, one had experimented with the use of localmaterials. One thing which particularly impressed me, was aprefabricated roof, made from the rather small bamboos, which wereso prevalent all around.This roof consisted of a number of roof trusses of about 3.5 to 4metre span with a 1.7 to 2.0 metre overhang on one side to coverthe verandah, constructed entirely of bamboos copying one of thewell known triangulated roof trusses, which I cannot remember, butI think it was the one shown herewith.A number of such trusses were assembled at ground level at 3.5 to4.0 metre intervals, linked longitudinally by means of bamboopurlins at suitable spacings, and braced longitudinally by furtherdiagonal bamboos to form the wind bracing. The whole formed a verylight, but strong, prefabricated roof of any length up to 35 or 40metres, which 4 to 8 Africans with the aid of forked poles, couldeasily lift onto the tops of the mud and wattle or mud-brick walls,which by this time had been built up to wall plate level: it wasanchored there by strips of hoop iron, fixed to the walls withlong nails, and the roof was then covered with thatch.Great difficulty was experienced in joining the bamboo componentsof the trusses. Nailing almost inevitably split all the bamboos,local creepers, and rough cord made from wild Sansevieria was thenused as bindings, but these rapidly suffered from attack by thealmost ubiquitous termite, the so-called White Ant.Eventually the best solution was found to be to wrap the joints inthin hoop iron, which in turn was nailed to the bamboos. Thebamboos of course split, but the tight binding of the hoop ironkept the bamboo splinters together. Owing to the dryness of theRuponda climate, there were no problems from corrosion.

A triangulated roof truss-3o-


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2.4. HUT CONSTRUCTION 1)From: Royal Engineers Training Memorandum (RETM)no. 17, s. 69, p. 125-1271. When other accomodation is not available, huts may be rapidlyimprovised in the Far East using local materials. Page 32 showsa small hut or "basha" capable of being constructed without theuse of specialized tools or material. This may be covered witha tent fly, building paper (such as "Sisalcraft", "Malthoid" or

"Ormonoid") or by thatching.2. Standard building materials are frequently in short supply inthe Far East. In these circumstances all-purpose hutting canoften be improvised from local timber or bamboo. The small hutintended for the temporary accomodation of people may not besuitable for other purposes. Page 33 shows the constructiondetails of a larger hut adaptable to many purposes such ashospital wards, offices, and stores.3. Although better if available, sawn timber is not a necessity.Satisfactory huts of this design are normally constructed from

jungle poles or bamboo, the only stores required being nails anda small amount of wire.It is available to use hoop iron, salvaged from packing cases,for reinforcing points.Thatching if correctly laid makes a good waterproof covering forthe roof and is very cool in hot weather.

1) Royal Engineers Training Memorandum.By courtesy of the Ministry of Defence; London, U.K.-31-


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1A

._:

_.(

1 .5 (rtcm) SAPLINGS

Construction: 4~t-.3t(70-5cm)aplings I.&Shed with lawyer vine equivalent.TASK p:,?sON,S 'TV .. Yi" :TIY-?3D Xormal output:Frame f machettes 1 One hut per 9 persons in 4-6 hours.Thatch ( 2Total. y 3

Figure 5. Traditional hut construction.


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i '4 ,' Y~LTEQNATIvE WITH&IT FLYWIQE kYW QE iF REQUIREDTwO ALTEP~AT YE IlOWS OF NEW PALM w Talrl A A ECllON ag, ALTERMAT=_.- - *--.. VENTILATION. -.

PLIN. --


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EXPLANATIONl.Ridge purlin and2. Side purlin3.Trough or valley4.Cornerconnection5.Hipconnection.5.Lean to roof_(pa7. Eaves.S.Boarding.g.Ridge ending.

10. Bamboo floor ontop of basement.

---34


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25 0 In the next ages (33....1) an English ranslations given f astudykythe former ayalDutch-IndianMedicalervices, ublishedin 1935, onerning ouse mp-menent or the purpose fumtrolling he plague.

Technical information on house improvement for the p~pggs--I----Y------------------------ -----------------of controllinq the plaqgg------------ -w--w --When trying to control the plague by improving houseconstruction, the aim should be to avoid contact betweenrat and man as much as possible. The aim itself alreadyindicates in which way the houses should be improved.Particularly it should be made impossible for the rats tonest without being noticed.In this text it is emphasized that it is hardly possibleto construct all parts of a house in such a way as to giveno opportunity for nesting, but if we can make sure thatthe places where nesting is possible are well visible orcan be inspected easily, we have already achieved the goal.

Some constructions dealing with simple dwellings constructedof temporary materials will be described. Furthermore,three constructions, frequently found in stone housesor in shops will also be dealt with. This technicalinformation remains restricted to the improvement of simplecontemporary dwellings but the, onsiderations that havelead to the chosen improvements can also give us an ideaof how new buildings of both temporary and permanent materialscan be kept free of plague-dangerous constructions.

-35-. ,.: , .:,. . .:-; ;.,:.:;.:y,:: *. ,*.:-. . ,. . .I .: .


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01 RIDGE PURLINWRONGroom for ratsnests .i

RIGHT

distance top bat-

wooden plugs

rafters at -least50 mm (2") th_ width not more than 50 mm

36 .

.


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Ridge Qurlinm-w -- --B-wThe first detail drawing shows a cross section of a ridgepurlin that can also be used for a hip. It is clear thatin case of a faulty construction the horizontal top surfaceof the ridge purlin is an ideal place for rats to nest.The mortar shown under the rafters is not used over thefull length of the ridge purlin and has fallen through theroof tiles while completing the roof at the top.This mortar, covered by ridge tiles, is usually of sucha bad quality that rats have no problems making holes andpassage ways in which they can nest and have access to thehollow bamboos.To solve these problems, the ridge purlin is placed insuch a way that the edge points upwards and the bamboosare sealed by nailing well-fitting wooden plugs into theends and the ridge tiles are placed directly on the toptiles.Mortar may be put on the ridge tiles to prevent them frombeing blown off. In order to be easily inspected, therafters must be at least 50 mm (2") thick and not morethan 50 mm (2") wide. The distance between the top sideof the ridge purlin and the bottom of the ridge tiles mustmeasure at least 100 mm (4"). The rafters.meeting at theridge purlin or hip must end against each other and notnext to each other in order to facilitate inspection.E'urthermore, hitewashing of the ridge purlin itself andthe inside roof surface of at least 750 mm (2'6") on bothsides of the ridge will make it difficult fot the ratsto nest without being seen.

37


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WRONG

SIDE PURLIN

RIGHT

RIGHT

I

single or doubledouble bamboowall with spaceinbe ween '1'bamboo wall withoutspace inbetween,fastened together bylaths at intervalsof 250 mm (10")otherwise 150 mm (6")

. .

-38 ..


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SX.g-eurlin---aThis construction concerns the transition of a given roofslope to a slope that is less steep. The open, hollowrafters and the ceiling joists, the space between thedouble bamboo walls and the space along the first ceilingjoist alongside the side purlin, are very'dangerous and faultyconstructions, because there appears to be no suitable solu-tion for the connection.Also the end of the binder protruding from the wallprovides an opportunity for nesting. The horizontal topsurfaces of the side purlin can be maintained if the ceilingcan be walked on in order to make inspection of the sidepurlin possible.In the process of improvement the ends of the hollow raftersshould be sealed by well fitting, nailed wooden plugs.In case of the double bamboo wall it should be made surethat there is no cavity.The two bamboo layers should therefore be fitted. loselytogether over the whole area. In case of the walls beingfastened by sticks the distance between the sticks shouldnot exceed 250 mm (10").When fastened in any other way, the distance should notexceed 150 mm (6").The first ceiling joist should be placed at least 100 mm (4")from the side purlin in order to make nesting impossible.The ceiling can be fastened to the side purlin by securelyfitted laths. The top side of the binder should not protrudefrom the wall for more than 30 mm (1"). If the bindersprotrude more, they should be sawn off at an angle of 45O.If the space above the ceiling cannot be rgached, the sidepurlin should be sawn off to a slant of 35 .

39


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0 ._3 TROJJGH UTTERWRONG

RIGHT

wooden-plug

9oodenrafters--I--


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Trough qutter-mm- -- m-Y--This construction applies to trough as well as valleygutters. The gutters concerned occur when two roof surfacesmeet. The trough gutter is horizontal and the valley gutterhas a slope. When the gutter boards are placed in the wrongway I rats have an excellent opportunity for nesting underthe zinc gutter.In addition the hollow bamboos that are usually notconnected properly to Lhe gutter purlin or the valley aredangerous.Improvement can be achieved in two ways:the top figure applies to bamboo as well as woodenrafters, the middle figure to wooden rafters only.When using bamboo rafters these should be carefullysealed by well fitting, nailed wooden plugs.It is obvious that the improved construction providesan adequate means of inspection.The middle figure applies to wooden rafters only becausethe ends would not be visible anymore.The side surfaces of the roof should be whitewashed overa width of at least 750 mm (2'6") on both sides of thevalley, for better rat control as these places are usuallyrather dark.

41


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0 CORNER ASSEMBLING OF ARCHIT@J7ESWRONG RIGHT

architraves not at same levelroom for rats nests

Inot shut off /

packing lath ,.maximum 30mm (1"1$ and slanted to 4 +

architravesi ot ZIF ame lt?Vd architraves at slime evel

,

lath wooden ceilinnrioints

I bamboo

bamboo boarding4/

/&chitraves at same level

IIIIIII

III

- 442 . .


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Corner assembling of architraves (1)-II------------ ---------------In many houses we find architraves that do not havE..thesame height. The ceiling joists are placed on the lowerarchitrave and the difference is made up by a packinglath that supports the rafters on the same level as thetop architrave.It is clear that when the bamboo wall goes as far asthis lath, there is a space between this lath and thelower architrave, where rats can stay unnoticed, as eventhe ends of the bamboo ceiling joists can not beinspected. In the improved version the bamboo wall endsat the lower architrave.Now the ends of the ceiling joists, securely sealed offby well fitting wooden plugs, are clearly visible. (If one of the architraves protrudes the other, then therequirement counts that the top surface must not projectmore than 30 mm (1") horizontally; if more, then thisshould be given a slant of 45 .In better houses we see architraves at the same level.The ceiling joists are then placed on a separate load-bearing beam. There is no objection to this as long asthe ceiling joists are wooden ones. If they are of bamboo,they should be placed on the architrave themselves in orderto be able to inspect them.

(1) Architrave= that lower part of a roof structure whichrests immediately on the column.

43


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HIPCONNECTION

RIGHTWRONG

hip placed on ridge purlin- hip placed againstip placed againstridge purlin-idge purlin-or notched in itr notched in it 1 I

hips notched-in ridge purlin

do not place rafters on meetgng.

--2 laths a-bove the hips on the.r_afters,distance betw& 1OOmm (4")Tiles and roofinr battens.1x-4 must not Drotrudg rhese laths

I /

44. ,. :*.-.. ,. *.:.;


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H&E connectionw--w------Quite often the hips of houses are placed on the ridge.It is quite obvious that this situation gives rats a grandopportunity to make nests unseen. That is why the hipsshould be placed against the ridge or notched in it.There is a special precaution that must be taken intoaccount, concerning the rafters. They may not be placedin such a way that they meet each other in the same pointas do the hips and the ridge. This point where hips andridge meet each other must be kept clear in favour ofvisibility.Furthermore a few laths should be placed at 100 mm (4")interval above the hips on the rafters. The roofingbattens and the tiles of the adjoining roof surfaces maynot protrude inside this area between the two laths so asnot to interfere with visibility. The tiles should beshaped so as to follow the angle.

45


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0WRONG

ccz

bambo?,

RIGHT

room forrats nests

DOUBLE PITCH-ROOF(porch or veranda)

/bamboo boarding

RIGHT

endsI

~100m

wooden plugsurveyable whenin the room

bamboo

6


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A lean to or single Eitch roof--------------- -II ---------The annex of a simple dwelling is usually covered by asingle pitch roof.In present constructions open hollow bamboo's are used asrafters, supported by a beam, and often against a doublebamboo-wall with space in between so that the ends of thehollow bamboo's are not visible at all.The improvement takes place by replacing the double bamboowall by a single one or a double one that is made of twolayers closely fitted together and by interrupting the wallwhere the ends of the rafters are. The hollowbamboos thathave been shut off by well fitting nailed plugs, can easilybe inspected when being in the living room.The beam on which the rafters rest should be slanted,because a horizontal top surface gives opportunity to makingnests unnoticed.

47


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0 CEILINGWR0N.G R I GH T

bamboo 4

RIGHT

ceiling joists

*b- -amboo. .

,PYg>+eilinnplaced-onceiling joistsi

-l--IF1s~ (4")ITt least----bamboo

bottoin f architrave is higher than.top of beam


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Ceilings----- -Ceilings that cover a whole room are allowed if they cannot be penetrated by fleas and are also connected to thewalls for this purpose. Furthermore we are to have amanhole size 500 x 500 mm (20"~ 20") that can be shutwell and the ceiling hanger must be strong enough to bearan adult person.Ceilings, that do not cover the whole room, do not have tobe unpenetratably by fleas. The danger of having ratsnests in the room above the ceiling is much less than.Furthermore we must take care to place the first ceilingjoist at least 100 mm (4") away from the architrave,while the ceiling joists are placed at least 100 mm (4")from each other on the beam where they meet each other,so as to avoid lodges that are very difficult to check.It sometimes happens that the bottom of the architrave ishigher than the top of the beam.If this difference in height is rather small, let us sayless than 100 mm (4") and the ceiling is in this casefastened under the ceiling joists then the space betweenthe ceiling and the bottom of the architrave is not veryeasy to see.When improving, the ceiling is placed on top of theceiling joists, so that the space mentioned disappears,If the bottom of the architrave is 100 mm (4") or morehigher than th

Documents

Bamboo in Building Construction