Goss's Roofing Ready Reckoner: Metric Cutting and Sizing Tables for Timber Roof Members, Fourth Edition

190 Pages·2007·1.603 MB·English

by  C. N. Mindham(auth.)

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GOSS’S ROOFING READY RECKONER
METRIC CUTTING AND SIZING TABLES FOR
TIMBER ROOF MEMBERS
Fourth edition
Revised by
C. N. Mindham
i
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(cid:2)C 1948,1987,2001,2008theestateofRalphGoss,Blackwell LibraryofCongressCataloging-in-PublicationData
PublishingandChrisN.Mindham
Goss,Ralph.
BlackwellPublishingeditorialoffices: Goss’sroofingreadyreckoner:metriccuttingandsizingtablesfor
BlackwellPublishingLtd,9600GarsingtonRoad,OxfordOX42DQ,UK timberroofmembers.–4thed./ChrisN.Mindham.
Tel:[phone] p.cm.
BlackwellPublishingInc.,350MainStreet,Malden,MA02148-5020, Rev.ed.of:Roofingreadyreckoner/RalphGoss.
USA 2001.
Tel:[phone] Includesbibliographicalreferencesandindex.
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Tel:[phone].Roofs–Handbooks,manuals,etc.
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TherightoftheAuthortobeidentifiedastheAuthorofthisWorkhas 3.Roofing–Handbooks,manuals,etc.
beenassertedinaccordancewiththeCopyright,DesignsandPatents 4.Engineeringmathematics–Formulae–Handbooks,manuals,etc.
Act1988. I.Mindham,C.N.(ChrisN.) II.Goss,Ralph.Roofingreadyreckoner.
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Firstpublished2008byBlackwellPublishingLtd textpaperandcoverboardusedhavemetacceptableenvironmental
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ii
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CONTENTS
1 Introduction 1
2 Roofingterminology 2
3 Calculatingthesizeoftimbermembers 8
Strengthandsectionsizecalculation 9
Howdowecalculatetheloadingontheroof? 15
Timbermembersizingdesign:example 15
4 Calculatingthelengthandcuttinganglesoftimbermembers:datatables5◦–75◦ 21
Thepitch 24
Usingthetablestocutacommonrafter 24
Hipjackrafters 29
Hiprafters 31
Valleyjackrafters 33
Theridge 33
Purlins 35
Metriccalculationtables 36
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Contents
5 Wallplates–strappingandgablestrapping 110
6 Windbracingandopeningsfordormersandroofwindows 112
Openingsfordormersandroofwindows 114
7 Roofingmetalworkandfixings 120
Nails,boltsandscrews 122
8 Roofcoverings–felt,battensandtiles 124
Underlay 124
Battens 125
Insulationandventilation 129
Choosingtheroofcovering 139
9 Roofcoverings–buildingdetaildrawings 151
Naturalslates 151
Concreteinterlockingtiles 154
Plainandpegtiles 158
Asphaltshingles 164
Metaltiles 167
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Contents
10 Toolsandequipment 170
Obtaininginformationfromthedrawing 170
Tocuttheroof 170
Settinguptheroofstructure 171
Roofcoverings 171
11 Health&safetyconsiderations 173
Accesstotheroof 173
Basicprinciples 173
Restorationandrenovationofexistingroofstructures 174
Newlyconstructedroofs 175
Theroofcovering 175
Conclusion 176
Bibliography 177
Index 183
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1 INTRODUCTION
Theaimofthisbook,whenfirstpublishedin1948,wastoprovidequickreferencetablesforthelength
andanglesofcutfortimbermembersinatraditionalcutroofconstruction.Today,whenmanyhouses
usetrussedraftersfortheirroofconstruction,thereisstillaneedforsomepartsofthoseroofstobebuilt
usingtraditionalmethods,especiallywiththeeverincreasinguseofatticroofstructures.Renovation
of older roofs, extensions and conversions all require knowledge of roofing from wall plate to ridge
andthecorrectdetailingoftheroofcoveringmaterialsthemselves.
Thisbookassumesthatabasicarchitecturaldesignoftherooftobeconstructedisalreadycompleted,
i.e.thespan,pitch,lengthandanyadditionalsupportingwalls.Guidanceisgivenonhowtocalculate
thesizeofindividualroofmembertimbers,thecuttinglength,theanglesandthecompoundcuts.The
book now also includes all aspects to be considered when choosing the roof covering, including the
suitabilityofthetilesorslatesforthepitchandexposureoftheroofconcerned,thechoiceofa‘warm’or
‘cold’roof,theconsiderationstobegiventothecorrectinsulation,andthepossibilitiesandavoidance
ofcondensationwithintheroofspacebydealingcorrectlywithventilation.
Finally,HealthandSafetymattersareaddressed,includingthe‘WorkingatHeightsRegulations’,load-
ingtheroofstructurewiththeroofcoverings,liftingcomponents,andthecorrectuseofpreservative
treatedtimber.
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2 ROOFING TERMINOLOGY
Wallplate The‘foundation’oftheroof,usually50×100mmwide,mustbebeddedsolid,leveland
straight on the top of the wall, or nailed to the timber framed panel and strapped in place to prevent
movementfromthestructure.
Purlin Themembercarryingpartloadofthelongcommonrafters,traditionallyplacedatrightangles
totherafterbutnowmorecommonlyfixedvertically.
Pitch Theanglemadebytheslopeoftheroofwiththehorizontal.Thismaybestatedindegreeson
thedrawing,ormayhavetobemeasuredbyprotractorfromthedrawing,ormayhavetobecalculated
bymeasurementifthenewworkistomatchanexistingroof.
Ridge The timber at the top of the roof where the rafters meet, giving a longitudinal tie to the roof
structure,commonly38mmthick,andofadepthequaltothetopcutontherafterplusapproximately
38mm.Thisdepthwilldependuponthepitchoftheroofandthetilebattenthickness.
Commonrafter Thetimberrunningfromtheridge,downoverthepurliniffitted,overthewallplate,
andtothebackofthefascia.
Jackrafter Thetimberrunningfromthehiprafterdownoverthepurliniffitted,overthewallplate,
andtothebackofthefascia.
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Roofingterminology
Figure2.1 Illustrationoftermsusedinchapter.
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Goss’sroofingreadyreckoner
Figure2.2 Illustrationoftermsusedinchapter.
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Roofingterminology
Valleyjackrafter Thetimberrunningfromtheridge,downoverthepurlin,downtothevalleyboard
orrafter.
Trussedrafter Aprefabricatedframeworkincorporatingrafter,ceilingjoist(ortie),andstrengthening
websformingafullytriangulatedstructuralelement.
Ceilingjoistortie Timbersupportingtheceilingofthebuilding,butoftenimportantly‘tying’thefeet
ofthecommonandjackrafterstogetherthustriangulatingandstabilisingtheroof.
Windbracing Usually25mm×100mmtimbernailedtotheundersideofraftersandtrussedrafters
runningatapproximately45◦ tothem,totriangulateandstabilisetheroofinitsverticalplain.
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