Table Of ContentZwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 11.3.2011 9:52 Uhr Seite 1
Wood
andWoodJoints
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 11.3.2011 9:52 Uhr Seite 2
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 24.3.2011 15:03 Uhr Seite 3
KlausZwerger
Wood
and Wood Joints
BuildingTraditionsofEurope,JapanandChina
WithaForewordbyValerioOlgiati
Second,RevisedandEnlargedEdition
Birkhäuser
Basel
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 16.3.2011 8:20 Uhr Seite 4
TranslationintoEnglish: Allphotographsarebytheauthor,unlessotherwise
GerdH.Söffker,Hannover noted.
PhilipThrift,Hannover
TranslationofForeword,Structural
TimberConstructioninChinaand Thisworkissubjecttocopyright.Allrightsarereserved,
additionstoIntroductionand whetherthewholeorpartofthematerialisconcerned,
Appendix:JulianReisenberger,Weimar specificallytherightsoftranslation,reprinting,re-useof
illustrations,recitation,broadcasting,reproductionon
Graphicdesignofthefirstedition: microfilmsorinotherways,andstorageindatabases.For
AtelierFischer,Berlin anykindofuse,permissionofthecopyrightownermust
beobtained.
Graphicdesign,coverandproduction:
ActarBirkhäuserPro ThisbookisalsoavailableinaGermanlanguageedition
www.actarbirkhauserpro.com (ISBN978-3-0346-0684-4).
Barcelona-Basel
©2011BirkhäuserGmbH,Basel
ACIPcataloguerecordforthisbookis P.O.Box,4002Basel,Switzerland
availablefromtheLibraryofCongress, PartofActarBirkhäuser
WashingtonD.C.,USA.
Printedonacid-freepaperproducedfromchlorine-free
Bibliographicinformationpublishedby pulp.TCF∞
theGermanNationalLibrary PrintedinGermany
TheGermanNationalLibraryliststhis ISBN978-3-0346-0685-1
publicationintheDeutsche 987654321
Nationalbibliografie;detailed www.birkhauser.com
bibliographicdataareavailableonthe
Internetathttp://dnb.d-nb.de Distribution:
ActarBirkhäuserD
Barcelona–Basel–NewYork
www.actarbirkhauser.com
RocaiBattle2
E-08023Barcelona
T+34934174993
F+34934186707
[email protected]
Viaduktstrasse42
CH-4051Basel
T+41615689800
F+41615689899
[email protected]
151GrandStreet,5thfloor
NewYork,NY10013,USA
T+12129662207
F+12129662214
[email protected]
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 16.3.2011 8:20 Uhr Seite 5
Contents
ForewordbyValerioOlgiati 6
Introduction 7
TheMaterial
ThePropertiesofWood 10
SpeciesofWood 32
WorkingwithWood
Uses 42
TheCarpenter 54
TheCarpenter’sTools 67
FormsofConstruction 78
TypesandFunctionsofWoodJoints
Typology 85
ClassificationSystemsintheLiterature 91
LimitstotheClassificationSystems 97
TheFunctionsofWoodJoints 100
WoodJointsandTheirEvolution
TheRoleoftheTool 112
BuildingTasksandTheirSolutions 132
LogConstruction 140
Column-and-BeamConstruction 153
RoofConstruction 176
TheInfluenceofClimaticConditions 211
AbundanceandScarcetyofTimber 226
WoodJointsasanExpression
ofAestheticValues
TheVisibleandtheInvisible 247
ProtectionandPrestige 253
ConstructionandDecoration 258
StructuralTimberConstructioninChina
BuildingMethods:LogConstructionand
Column-and-BeamConstruction 268
StructuralWoodPreservation:RaisedPlatformandCantileveredRoof 275
ChoiceofMaterials 278
TheStructureandConstructionofTempleBuildings 279
TheConstructionPrinciplesofBracketComplexes 289
Dougong 290
TheEconomicsofConstruction 297
Bibliography 306
Acknowledgements 311
IndexofPersonsandBuildings 312
IndexofPlaces 313
SubjectIndex 314
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 24.3.2011 14:15 Uhr Seite 6
Foreword
Aftersearchingforacopyofthisbookandintheknowledgethat
the English version was already out of print, we contacted the
authorandthepublisherdirectly.Notonlywereweluckyenough
toreceiveoneofthelastremainingcopiesbutalsolearnedthata
neweditionwasinpreparation.Thisisnowavailableandweare
delightedthatthiswonderfulbookcanonceagainfascinatenew
readers.
Illustratedwithbeautifulphotographsandmeticulousdrawings,
thebookdetailsthelongtraditionanddevelopmentoftimbercon-
structioninEuropeandAsia.Architectsandcarpenterscultivateda
highlydevelopedunderstandingofthismaterialandthepossibili-
tiesitoffered.Thepathofforcesandthespecificpropertiesofthe
material fundamentally determined the formal appearance of
timberconstructionsandtheirdetails.
Timber construction has always related closely to the engineer’s
way of working and, compared with load-bearing construction,
wasveryhighlydeveloped.
Thecultureofbuildingwithwood,itstradition,itsregionalandcli-
matic particularities, its influences and developments are docu-
mentedinimpressivedetailinthisbook.
Inthelastfewcenturies,buildingwithwoodhaschangeddramatic-
ally.Adhesivesandsteelcomponentshavechangedthecharacter
ofitsconstruction.Incontemporaryarchitecture,woodisusedfor
surface cladding or in construction in the form of resin-soaked
materialssuchaschipboardorsandwichpanels.Knowledgeand
skillsofthekinddescribedinthisbookarerarelyseentoday.
Myownbuildingsfromthepastfewyearshavebeenmadeprimar-
ilyofconcrete.Withconcreteonecanbuildhousesthataremade
almost entirelyofasinglematerial.Reinforcedconcretecansus-
taintensileandcompressiveforces,canbeusedasaslaborabar
andcanbeassembledonsiteinphases;themanifestationofan
ideatoformalargerwhole.
Allthisispossiblewithwoodaswell.Itisjust thatwenolonger
knowwhatthismaterialiscapableofandlacktheskillstoworkit.
Andthatissomethingwecanchange.
Inthisrespect,thisbookisawelcomeinspiration.
ValerioOlgiati
Flims,December2010
6
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 16.3.2011 8:22 Uhr Seite 7
IntroductiontotheSecondEdition
Therearetwoquestionswhichcouldberegardedasathreadlink-
ingthevarioussectionsofthisbook.Firstly:“Whatwerethecon-
ditions which governed the development and form of timber
connections?”And secondly:“Can the timber connections of Eu-
ropeandJapanbecompared?”Bothquestionsareinterdependent;
thesecondcannotbeansweredwithoutadetailedconsideration
ofthefirst.
Ifalltheessentialfactorswhichhavecontributedtotheformation
of a timber connection are elucidated,i.e.the material itself,the
personworkingthematerialandtheproducttherebycreated,then
wecometotheconclusionthatajuxtapositionofthesetwocul-
turesoftimberconstructionisindeedpossiblebutthatabalanced
comparisonoftheachievementsmustberegardedasproblematic,
ifwecancountenancesuchathingatall.
To the sensitive observer, wood joints often allow the train of
thought of theircreator tobefollowed.(Thecarpenterproduced
the joint;from its form we can deduce what he thought in each
case!) The creator’s design considerations have taken on a form
whichwetodayinterpretasareflectionofwhatwasonceacknow-
ledgedasgood.Ontheotherhand,thecareshownintheexecu-
tion, thereadiness toproducecomplexjoints,hasnot alwaysre-
mainedthesame.
This book describes and explains joints made exclusively from
wood, i.e. without adhesives and without metal connectors, to-
getherwiththeiroriginsandevolution.Todothis,Ihavestudied
theexamplesfoundtoday,examinedthescientificliteratureavail-
ableand,whereinformationwaslacking,carefullysupplemented
thisinorder tofillin thegaps.Particularattentionispaid to the
materialaswellastoclimatic,technical,woodworkingandartistic
influences.Itmightappearproblematicthatindoingsotheorigins
ofcertaintypesofjointsarediscussedinthecontextofveryspe-
cific causes.If,for example,the development of splicing joints is
dealtwithinthechaptercoveringdependencyontheoccurrence
ofwood,thenthisshouldnotbetakenasbeingmoreimportant
thananyotherfactorinthecreationofsuchjoints;likewisethein-
fluenceofclimaticconditionsforthedescriptionofboardjointing.
Thereaderisreferredtotheselectivenatureoftheexamplesgiven
in the chapter on the relationship between timber connections
andbuildingtasks.
Theclassificationemployedin thechapteron the typesofwood
joints,whichthereadermightfeelisinsufficientlydifferentiated,is
intendedtoreflecttheconsiderationgiventothespecificmaterial
properties –oncedecisiveininfluencingtheconstruction.Thechar-
acteristicsofwood,notwopiecesofwhichareeveridentical,have
certainlynotbeenaccordedadequateattentionbyeverycarpenter
inthepast,but,inevitably,toamuchgreaterextentthanisthecase
today.Aslongasitwasusedinitsnaturalform –andthatisthe
themeofthisbook –,thecomplexityofthematerialwasaccepted
forwhatitwas.Fortoday’stheoreticalapproachthismeansthat
any classification, if it is to achieve a more detailed distinction,
musteithersetartificiallimitsandexcludephenomena,orleadto
perpetualrepetitions.Onthewhole,theinfluencesdescribedhere
whichhelpedshapejointsinEuropeandJapanwereabletoberead-
ilycompared,atleastinthisselection.Inordertomakethisclear,
theaimhasbeentotrytoplaceaJapaneseequivalentalongside
7
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 16.3.2011 8:22 Uhr Seite 8
everyexamplechosenfromEurope.This,atthestartperhapscon-
fusing,methodwastheonlysolution,whenseeninthelightofthe
enormouswealthofmaterial,tomakingtheintendedcomparison
easilycomprehensibleonourjourneythroughthousandsofyears
oftimberarchitecture.
The reader will notice that many dates remain vague or are not
evenhintedat.Thereisagoodreasonforthis.Thedateofthecom-
pletion of a building can be ascertained.The evolution of a con-
structionform,e.g.thesparroof,cannowbetracedbackfurther
andfurtherthankstomoreintensiveresearchworkinrecentyears.
Nevertheless,therestillremainsthefactthattheremayhavebeen
other,evenearlierexampleswhichhaveinthemeantimebeendes-
troyedandwhichwillalwaysremainanunknownvariable.Looked
atinthiswayitisperhapseasytounderstandwhytheregularlist-
ingofdateshasnotevenbeenconsidered.
AwordortwoabouttheconstantlyrecurringJapanesetermsisne-
cessary.Generally,nocapitallettersareemployedunlesstheword
isapropername.Thenamesofpeoplearereproducedinthetradi-
tionalJapaneseform,i.e.thesurnamebeforetheforename.Tem-
plesorshrinesareculturalcentresofBuddhismorShintoism.AJa-
panesepersoncandeducefromthenameTodai-jithattheobject
inquestionisaji,i.e.atemple.However,inadditiontojitherearea
numberofotherJapanese termswhichallmean templeandyet
othersforshrine,jinja,forinstance.Inordertoavoidtautological
constructionslike“TodaiTempleTemple”,inthecaseofaconflict
wehavedecidednottodistinguishbetweenshrineandtemplefor
the reader from other cultures.The difference can be recognized
fromvariousdetailsonoraroundthestructure,anditisirrelevant
for the wood joints presented in this book.Those who travel to
Japanwillquicklydiscoverthe,evenforvisitorsfromtheWest,im-
mediatelyrecognizabledistinguishingfeatures.
OfallthemanymessagesIreceivedinresponsetothefirstedition
ofthisbookin1997,notonetookissuewiththefactthatEurope
andJapanwereratherunequalpartnerstocomparewithonean-
other.Formyself,however,thisaspectbecameamatterofincreas-
ingconcern.Sowhenthepublisherapproachedmewiththeinten-
tionofbringingoutanewedition,Ifeltcompelledtoputthisright
andexpressedthewishtoaddachapteronhistoricaltimbercon-
structioninChina.
Therearemanyfascinatinglinesofdevelopmentintimberarchi-
tecture,butifaskedtonamethemostadvancedculturesofbuild-
ingwithwoodIwould,without hesitation,choose theEuropean
andEastAsian.IhaveconsciouslyavoidedspeakingofWesternor
FarEasternbuildingtraditions.Theterm“FarEast”reflectsaeuro-
centricstandpointthatrefersbacktotheeraofEuropeanImperia-
lism.IntheBritishEmpire,theterm“FarEast”servedtodividethe
AsiancontinentfromtheterritoriesoftheNearandMiddleEast.
TodaywespeakofSouthAsian,SoutheastAsian,andEastAsianre-
gions.Thevarietyof timberconstructionsinSoutheast Asiamir-
rorstoacertainextentitsgeography.Onecantracereciprocalin-
fluencesbetweenthedevelopmentsinSoutheastAsiaandthose
inEastAsia.Intheborderregioninparticular,itisoftennotpos-
sibletoclearlyidentifythelocalarchitectureasspecificallySouth-
eastAsianorEastAsian.
Nevertheless,whenonefollowsthehistoricaldevelopments,itis
possibletotraceveryclearlythedevelopmentsofChinesetimber
construction. For them, the ruling periods of foreign dynasties
8
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 24.3.2011 15:08 Uhr Seite 9
were not seen as a break but,on the contrary,as an enrichment
(Liao,Yuan)and–dependingonone’sviewpoint–anendpointora
culmination (Qing).The Japanese building culture, as previously
mentioned,owesitsdevelopmenttoanotinconsiderabledegree
to examples and techniques imported from elsewhere, such as
Korea,butaboveallfromthevastChineseEmpire.
In the new chapter I have again followed the principle of a
colourfulmixtureofvernacularbuildingsandso-calledhigharchi-
tecture.Therearetwomainreasonsforthis.Thefirstisthattheor-
ganisationofthebookisbasedoncriteriathathavenothingtodo
withthisdistinction.Thesecondcanbeattributedtoafirmbelief
thatsingularexamplesofhigharchitecture“mustbeseeninrela-
tionto,andinthecontextof,thevernacularmatrix,andareinfact
incomprehensibleoutsidethatcontext,especiallyasitexistedat
thetimetheyweredesignedandbuilt”.1Thatsaid,thisviewpoint
shouldinnowaycallintoquestionthefactthatawholeseriesof
constructional phenomena in vernacular architecture are drawn
fromexamplesofhigharchitecture.Idonot,however,subscribeto
thegeneralopinionthatdevelopmentsinelitearchitecture,where
theyaresometimesdescribedasbeingcharacteristicofarchitec-
tural styles,gradually diffuse into vernacular architecture where
theythenreappearasimitations.
HadIwishedtofollowthesameprincipleofdirectcomparisonbe-
tweenEuropeanandJapanesebuildingtechnologyfortheChinese
examplestoo,Iwouldhavehadtorewritetheentirebook.Thiswas
neither in the interest of the publisher nor in mine.I decided in-
steadtoappendthechapteronChinesearchitectureasaself-con-
tainedchapter.Thereaderwillhavenodifficultyincomparingthe
examplesshownwiththosefromJapanorthosefromEurope.That
is not least thanks to the critical and sensitive work of Andreas
Müller,whowastheeditorinchargeofboththefirsteditionand
thisexpandededition.
AmosRapoportwasoftheopinionthatbuildingscanbeexamined
in a variety of different ways:“One can look at them chronolog-
ically, tracing the development over time either of techniques,
forms,and ideas,or of the thoughts of the designer,or one can
studythemfromaspecificpointofview.”2ThecomparisonofEu-
ropeandJapanmixesbothapproaches,asdoesthestudyofbuild-
ings in China,albeit taking a rather different viewpoint.This ap-
proachcreatesaformalconnectionbetweentheexistingsection–
whichhasbeencheckedandslightlychanged,withsomenewpho-
tographs–andthenewchapter.Withthisadditiononecannowle-
gitimatelyspeakofacomparisonofthedevelopmentsinEurope
andEastAsia.
1Rapoport,1980,p.284
2Rapoport,1969,p.15
9
Zwerger_Holzverb_Inhalt-dt_en.qxd:Holz-deutsch 11.3.2011 9:52 Uhr Seite 10
TheMaterial
Thepropertiesofwood
“Byapplyingappropriatetoolsandtechniquestoagoodpiece
of timber,a woodworker’s imagination is limited only by the
natureofhismaterial–amaterialthatoftenseemstohavea
lifeofitsown.”1
Every material is distinguished by characteristics peculiar to
itself.Knowledge of these is a necessary prerequisite for pro-
cessing the material appropriately.Wood lets us know quite
definitely and unpleasantly when it is not being treated cor-
rectly, whether due to negligence or lack of knowledge. But
woodalsoobstructsuswhenwetrytounravelitsmechanical,
physicalandchemicalproperties.Manymoderntextbooksat-
tempttopresentthematerialinawaywhichjustifiesthistheo-
reticalapproachtoitsuse.Twistedfibres,bowsandcolourdis-
crepanciesareonlyreferredto,ifatall,asabnormalitiestobe
cutout;beauty,asanon-technicalterm,isanunknownword.
All the properties of wood are interlinked.They interact with
eachotheroraredependentoneachotherinsuchawaythat
1 Thejointsofthediagonalbracing
thistextbook-typeofclassificationisquitesimplyinadequate membersonthisbridgebetweenAppen-
ifwewishtoexplaintheconnectionbetweenthecharacteris- zellandSchlattinSwitzerlandareso
tightlyrestrainedthatsettlementatthe
ticsofwoodandthecultureofwoodworking.
cornerintheleftforegroundhascaused
The loading capacities of timber in tension (Fig. 1) and com-
thewoodtosplit.
pression(Figs2&3),inbending(Fig.4)andshear,i.e.theme-
chanicalproperties,needtobeconsidereddirectlyandvisually,
as apprentices once did on their long way to becoming mas-
ters.Thepracticalreappraisalofwhathadbeenseeninactive
workanddailyroutinewasinanycaseonlyachievedcompe-
tentlybyveryfew.Thesizeofthecross-sectionisoffundamen-
talsignificancefortheloadingcapacity.Theoversizedmembers
oftenencounteredinolderelements,possiblynotunaffectedby
considerationsofproportion,i.e.partlydeterminedbyaesthe-
tics, undeniably contributed to the preservation of the ma-
terial.Otherauthorsdisputesuchoversizingandprove“thatthe
timber constructions investigated from the period between
1000and1800areoftenloadedtothelimitoftheircapacity.”2
According to David Gilly in 1797:“For example, the machine
master Reuss from Dresden cut the heavy truss posts in the
town’soperahousetosuitthemachineryinsuchawaythata
narrowopeningwascreatedthroughbothtrussposts.Hewas
verywellawarethatthetrusspostswouldremaincapableof
takinganyloadlikelytobeputonthem.”3Examplesofoversiz-
ing are the (sometimes) original columns of Norway’s stave
churches,4Switzerland’swoodenbridges,whicharecapableof
carrying today’s heavy road traffic,5 or Japanese temples and
shrines.ThefireintheHoryu-jiin1949canberegardedasan
exampleofjustwhatstresseswoodcanwithstandevenafter
1200years.Thecolossaldimensionsofthecolumns,each1.5m
in diameter,are certainly to thank for the fact that sufficient
2 Intechnicaltermstheloading
undamaged timber remained to guarantee the survival of a
capacityparalleltothegrainis
largepartofthestructureintact.6Intotalcontrasttothisare greatest.However,inastructure,as
thesometimes“stupidityprescribedstandardizedsizesforall compressiveforcesincreasesodoes
thesusceptibilitytobuckling.–
postswhichwouldhavebeenheavierinplacesiftheconstruc-
CowshedonafarminZaunhof,Tyrol,
tionhadbeenlogicallyworkedout.”7 Austria.
10
