best practice section 3 guides superstructure

BEST PRACTICE GUIDES

SECTION 3 SUPERSTRUCTURE

3.1 STRUCTURALFRAMEAND/ORLOADBEARINGWALLS

3.2 EXTERNALENVELOPE

3.3 CAVITIESANDINSULATION

3.4 DPC’S&TRAYS

3.5 CHIMNEYSANDFLUES

3.6 INTERMEDIATEFLOORSTRUCTURE

3.7 LINTELS,BEAMS&OTHERSTRUCTURALELEMENTS

3.8 BALCONIESINCLUDINGFIXINGS&WEATHERPROOFING

3.9 FIRESTOPPING&SOUNDPROOFING

ThisisoneofthelargersectionsofthePrideintheJobmarkingsheetandcoversallaspectsofthesuperstructurebuildaboveground.Structure,brickwork,blockwork,timberframe,weatherproofingandaestheticfinishareallconsideredhere.

SECTION 3 SUPERSTRUCTURE

Our series of Best Practice Guides will take you through what the Pride in the Job judges look for at each stage of construction and when considering the site manager’s overall organisation and management skills.

ThePrideintheJobmarkingsheetusedbyourjudgeshas44markinglinessplitacross9sections.Thejudgeswillgiveascoreforeachline–wherethereisnoworktomark,thatlinewillbeleftblankandnomarkgiven.Amarkof4indicatescompliancewithNHBCStandardsandwithBuildingRegulations.Amarkof5indicatesextraattentiontodetailoverandabovecompliancestandards.Amarkof6wouldindicatethatmuchofwhatthejudgeshaveseencannotbeimprovedupon.Amarklessthan4wouldindicatevaryingissuesrelatingtoworkmanshipandnon-compliancewithNHBC’sStandards–thegreatertheissueornumberofthesameissue,thelowerthemark.Thefinalscorewillbeallthemarksawardedexpressedasapercentage.

TheseGuidessetoutwhatthejudgesarelookingforwithclearhintsandtipsonthesortofpracticethatwillleadtohighermarks.

Clearlyitisimpossibleintheseshortguidestocovereverysinglepointofconstruction–wetryheretocoverthemainissuesthataretakenintoaccountwhenconsideringamarkforeachscoreline.

Whenlookingatthephotographs,considereachoneinthecontextofthescorelineheading–don’tbedistractedbysomethingelsethatisn’tasgood–thatwillbemarkedaccordinglyelsewhere.

BEST PRACTICE GUIDES

BESTPRACTICEGUIDES-SECTION3

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3.1 - 1 3.1 - 2 3.1 - 3

3.1 STRUCTURAL FRAME AND LOAD BEARING WALLS


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SECTION 3 - SUPERSTRUCTURE

3.1 STRUCTURAL FRAME AND LOAD BEARING WALLS

Thisscorelinerelatestothequalityofbuildoftheinnerleafoftheexternalwall(eitherblockworkortimber)andanyinternalload-bearingpartitionorseparatingwalls.

Images 1, 2 and 3:Theformingofopeningsinthewallforwindowsanddoorsandthebuilding-inoffloorjoistswiththeblockinginbetweenareallconsideredbythejudges.Image1showsasimpleexampleofwherethegaugingoftheblockworkhasyieldedafulldepthblockunderthebearingpointofthelintel–theuseofcutblocksorbricketteswouldbemarkeddown.

Separatingwallsshouldreceiveparticularattentiontoavoidsoundtransmittanceandintimberframeconstruction,thepositionofthewallstudsandthefixingofthepanelswillbetakenintoaccount.Image2showsblockworktightuptothejoists–excellentbeam-fillingwheretherehasbeenclearcareandattentionbythebricklayers.Goodworkwiththesealanttoo,whichmayhavebeenrequiredforRobustDetailsandsoundinsulation.

Blockworkshouldbekeptcleanandcutswellexecuted–especiallyforthoseawkwardangledcornerswheresometimes‘cutandstick’unitswouldworkverywell.

Constructionofmasonrywithinheightlimitationsoftheproductduringbuildisalsoimportant.Weseelotsofgablewallsbuilt7or8courseshighinblockworkwithoutbeingbackedupandsupportedwithbrickwork,thisisabreachoftheNHBCStandardsandareportableitem.

Extramarksmaybeawardedifthejudgesseethatthesitemanagerisgivingparticularfocustotheaccuracyofworkandanunderstandingofthestructuralprinciples.Inimage3,thoughthasbeengiventotheprecisepositioningofthepadstonehere.It’sattherightleveltoowithnopacking,otherthanadoublelayerofdpc.Intimberframedconstruction,thedesignandapplicationofeffectivecheckingsystemsforconnectionsdemonstratesagoodappreciationofthechallengesinvolved.Furthermoreneatnessofthebuildprocessshouldbeconsideredbythesitemanagerandtrades.

Theworkshownintheseimageswouldattractamarkof5.


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3.2 EXTERNAL ENVELOPE

3.2 - 5 3.2 - 6


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3.2 - 4


3.2 - 7


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Images 4, 5, 6, 7, 8 and 9:Thejudgeswillmainlylookatthequalityoftheworkmanshipwhich,forbrickwork,shouldincludebonding,gaugeandwell-filledjointstopreventexcessivewaterpenetration.Thevisualimpactoftheconstructionisimportant.Theimageshereshowsuperlativecraftsmanshipintheexecutionofmainwalling,corbelsandcutbricksaroundarchways.Theworkshownherewouldallreceivefullmarks.

Thebricklayers’attentiontodetailandanyfeatureworksuchasarchesshouldcomplementtheconstruction.Correctlypositionedandformedmovementjoints,includingsealant,willalsobemarked.

Particularcareandattentionneedstobemadetointernaljointstomakesurethepointingisneatandeven;Image7showsalovelyexampleofaninternalcornertoabrickchimneywherethebondiscompletelyuninterruptedaroundtheinternalcorner.

Anypreformedfeaturepanelswithincladdingsystemsandtheirrespectivefixingswillalsobeconsidered.Theinstallationofcladdingshouldpreciselyfollowmanufacturers’instructionsandtherequirementsofBBAcertification.

Toreallydrivethehigheststandardsonsite,maintainingverticalperpendjointsonmasonrywithahighqualityofworkingeneralwillreapdividends,asbeautifullydemonstratedinImage8onablockofthreestoreyapartments.

Workmanshipshowninthese6imageswouldeasilyattractamarkof6fromthejudges.


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3.3 CAVITIES AND INSULATION

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3.3 - 12 3.3 - 13 3.3 - 14

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Images 10 and 11:Cavitywalltiepositions,typeandnumber,spacingsandcleanlinessareimportantforstabilityandthepreventionofwaterpenetration.Aminimum50mmbeddinginoneachleafofsuperstructureshouldbeachieved.

Theinsulationshouldbeofthecorrecttypeandthicknessforthelocationofthebuilding,bearinginmindthatfullfillcavityinsulationcannotbeusedinseverelyexposedareasinaccordancewithNHBCStandards.Insulation,whetherpartialfillorfullfillshouldbeadequatelyrestrainedinplaceanditshouldbecontinuoustopreventcoldspots.Thereshouldbenomortardroppingsrestingontopoffullfillcavityinsulationbatts.

Whenusingpartialfillinsulation,cavitiesshouldmaintaintheminimumwidthof50mmandbefreeofdebristhroughoutitsentirety.Theinsulationshouldbetightupagainsttheinnerleafusingthecorrectwalltiesandclips.Onepointofconcernwithimage10isthattheblockworkisabithighwithoutbeingbackedup–morethan6courseswouldnotbeacceptable–sopossiblyalostpointhere;soeventhoughtheworkmanshipisveryneat,ifthisisamorewidespreadissue,itcouldwellbemarkedasa3.

Forextramarksahighstandardofdetailing,accuracy,alignmentandaparticularcleanlinessofwallties,DPCtraysandweepventsisneeded.Insulationshouldbenoticeablyclearofdebristhroughtheuseofprotectivemeasureswhilstworkingonthewall.Judgeswillbeimpressedwithinnovative,effectivesolutions.Image11isatextbookexampleofhowtokeepcavitiescleanwithflushedupbricksandspotlesswallties–afull6marksfromthejudgeshere.

Images 12, 13 and 14:Incontrasttotheabove,thisisdefinitelynotwhatthejudgeswanttosee:

■ superstructuresthatdemonstrateamixtureofbothexcessivemortardebrisinthecavityorbrickworkandblockworkwithjointswhichremainunfilled

■ blockworkthatisn`tbondedcorrectlyinthecornersandcreatesstepswheremortarcanbecomelodged

■ off-cutsoftimberjoistsandbricksthatcanbecomepresentespeciallywhereBuildingRegulationsarenowencouragingwidercavitywidthstomeetwiththerequirementsofPartL.

Goodaestheticstotheexternalcomponentofsuperstructurescoupledwithclean,clearcavitieswillputyouontherightroadtogainingaboveaveragemarksinthissection.Allthesephotoswouldmeritamarkof3atbest–possiblyloweriftheseissueswereseenasamoresite-wideissue.


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3.4 DAMP PROOF COURSES AND CAVITY TRAYS

3.4 - 15


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3.4 - 16 3.4 - 17


3.4 DAMP PROOF COURSES AND CAVITY TRAYS

Images 15, 16 and 17:DPCsandcavitytraysshouldbeinstalledatthecorrectlevelwithstopendsandcorrectlypositionedweepholeswherenecessary.

VerticalDPCsshouldbeinstalledtoopeningsinthebrickworktopreventwateringressoccurring.Image15showstheverticaldampproofcourseisinstalledaboveboxbaywindowtopreventwatertrackingacrossthebrickworkbycapillaryactionandintotheinternalspace.Image16showsanalternativepreformedverticaldpcthatallowsforthebondingtocontinuethrough,ratherthantreatingitasamovementjointasinimage15.Youshouldbemindfulofanysimilarareaswheredampproofcoursesshouldbeinstalled.

Preformedplasticcavitytraysshouldbeusedonanyroofabutments.TheyneedtobeadequatelysetouttotakeaccountoftheinstallationoftheroofbattenandtilewhilstalsoallowingtheminimumupstandinaccordancewithNHBCStandards.Theseshouldbefreeofmortardebrisandaweepholeshouldbeplacedonthelowesttraytoallowforwateregress.Preformedsteppedcavitytrays(image16)aretobecarefullysetoutusingprofilesorapatternspar.

Forthebestmarkstheuseoftemplates,ahighstandardofdetailing,accuracy,alignmentandcleanlinessoftraysandweepholesisrequired.

Note:TheNHBC3DviewerAppwhichisavailableforfreeoniPhoneandAndroidisagreatpictorialassetinassistingyouwithhighlydetailedandcriticalareasofconstruction.


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3.5 CHIMNEYS AND FLUES

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Images 18, 19, 20 and 21: Flueblocksorliners,iftheyarebeingused,mustbeinstalledthecorrectwayuprelativetotheirclassificationandshouldbebondedinorsupportedfortheirfullheight.

Testingofthefluebyuseofsmokebombsorotheralternativemeanscanbeconcludedandconfirmedatthispoint.Image19showsthatthissitemanagermakesanoteonthechimneybreastaspartofhisqualitymanagementsystem.Havinggoodcontrolsystemslikethiswillscorewellinsection9.5.Anappropriateformationofacavityaroundafluemustbeinstalledwherenecessary.

Neatandcompliantinstallationoffactory-madechimneysandtheirstructuralsupportandfirestoppingisveryimportant.These`dummy`chimneysastheyareoftencalledshouldbeassembled,erected,anchoredandprotectedinaccordancewiththemanufacturers’instructions.Theseshouldbeaccessibleonsiteforreference.

Thereisveryhighpotentialforwaterpenetrationthroughtheroofwherechimneysexitclosetotheeavesofapitchedrooforthroughaflatroofsoitisimperativethetraysandflashingsareinstalledinthechimneyandarecontinuoussothatalldamppenetrationisprevented.TheseleadflashingsintheexternalchimneyconstructionshouldbeappropriateandcomplywithNHBCStandards.Leadworktochimneyscouldbemarkedhere,orinSection4.5.

Note:TheNHBC3DviewerAppwhichisavailableforfreeoniPhoneandAndroidisagreatpictorialassetinassistingyouwithhighlydetailedandcriticalareasofconstruction.


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3.6 INTERMEDIATE FLOOR STRUCTURE

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3.6 - 24


3.6 INTERMEDIATE FLOOR STRUCTURE

Images 22, 23 and 24:Thejudgeswillbelookingatthestructuralfloor,whethertimber,steel,pre-castorin-situconcrete.Allrequiredstraps,nogginsandstruttingshouldbefixedinpositioncorrectly,whichincludesbearingonfullblocks,notonjoints.Restraintstrapsneedtobefullysupportedbynoggings–withtheendofthestrapturneddownsoastopreventitvibratingtotheundersideofthefloorstructure.Theworkshownhereisagood4marks,possiblya5.Certainlyifanextranoggingwasinstalledtosupporttheflyingendofthestrap,thatwouldmeritastrong5orperhapsevena6.Image23showsthatsomethoughthasbeenputintoensuringthatthestrappullsonafullblock;thesurroundingmasonryonthiscoursecanbeadaptedtofit.

Correctwallinterfacesmustbeusedi.e.hangersorbuildinginofjoistsandbeamsmustbecompliantwiththeNHBCStandards.Thequalityofworkmanshipisvitalforthiselementofconstruction,particularlyregardingseparatingwallsandtherequirementtoavoidsoundtransmittance.Thebuildinginofjoistsintoloadbearingwallsmustbedoneinaneatandtidyfashion,forexampleasshowninimage24wherefullblockshavebeenusedtofillthegapsbetweenthejoistswithnofuss–cleansharpwork.

Precautionsagainstdisproportionatecollapse–whateverthesystemofbuild–mustbecorrectlyinstalled;theseareusuallythetwistedlateralrestraintstrapsweseeaffixedtothelowerchordofthejoist–notthestandardlateralrestraintstrapsorsupportstrapsastheyareotherwiseknown.


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3.7 LINTELS, BEAMS AND OTHER STRUCTURAL ELEMENTS

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3.7 - 27 3.7 - 28 3.7 - 29

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Images 25 and 26:Thecorrectlengthandbeddingoflintelbearingsareimportanttoensurefulldistributionoftheload.

Padstonesshouldbeoftherequiredsizeandpositionedcentrallybelowthebeamorlintelinordertoevenlydistributetheload.Inblockworkwalls,fullblocksshouldbeusedforlintelbearingswithcorrectlybondedblocksbelow.Girdertrussbearingsarealsoconsideredunderthisheadingandassuch,shouldbeconsidered.MildsteelbeamsorRSJ`sshouldbepaintedtoensuredurabilityinaccordancewithNHBCStandards.It’snotclearfromthisphoto,butifthisistwobeamsthatneedtobeconnectedtogether,thetighteningoftheboltsmustbedonebeforeanyloadingisapplied.

Theworkshownherewouldbemarkedata4,orpossiblyamarginal5.

Images 27, 28 and 29:Whenconsideringtheplacement,bearingandlocationoflintelsyoushouldavoidthefollowingissues.

■ lintelsthataretoobigfortheopeningandencroachingintoortravellingfullyacrossthecavity

■ mixingofmaterials,forexample,facebricksoverlintelsorinadequatebearingonahalfofabrickwhichisfurtherunderstressbycarryingtheweightofthefirstfloorjoists.Considertheoverallareaofconstructionandtheimplicationsofnotgettingitrightfirsttime

■ poorbondingofmasonrythatleadstopooralignmentofperpends

■ inadequatepadstoneswithinadequatesizing–builtasanafterthoughtandoutofinappropriatematerials

Withimage29,whilstbluebricksmightjustworkasapadstone,themoreseriouserrorherearethestraightjointsinthemasonrybelowwhichsignificantlyweakensthewallunderthatload.

Theworkshowninimages27,28and29ispoorandwouldonlygeta2ora3–remedialworkwillberequiredtoresolvetheissues.

Ourbestadviceishaveapictureinyourmindofhowtheconstructionisgoingtolook.Howareyougoingtointerpretthetechnicalinformationonthedrawingintothehousethatyouarebuilding?Isitgoingtobecompliant?Isitgoingtolookasgoodasitpossiblycanbeorareyoujustgoingtoletthetradesoffertheirinterpretationandbemarkedaccordingly?


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3.8 BALCONIES INCLUDING THEIR FIXINGS AND WEATHER PROOFING

3.8 - 30 3.8 - 31


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3.8 BALCONIES INCLUDING THEIR FIXINGS AND WEATHER PROOFING

Images 30 and 31:Balconiesmustbeaccuratelyaligned,installedandcorrectlyfixedbacktothemainframeofthebuilding.Thejudgeswilllookforcorrectbalconyguardingmaterialsandgaps(iebenon-climbableandbeoftherightheight).CorrectdrainageforthebalconydesignismostimportantandshouldbeinaccordancewithapproveddrawingsandmeetNHBCminimumrequirements.Image30showsbalconiespartlycomplete–glassbalustradinghasyettobeinstalled.However,theworksofarlooksverycompetentandwouldmeritascoreofatleasta5.

Image31demonstratesaneatweatheringupstand.Anadequatesealingoffixingsshouldtheypenetratetheweatherprooffabricisvital.ThisisahighriskareaofconstructionsoitiscriticalthatbalconywaterproofingandthresholddetailsareapprovedbyNHBCpriortobeingconstructed.Thisimageshowsaneatlyconstructedsplashzonedetail,splashzoneheighttobeamin150mmabovedecking.Noteweepholesabovetraypositionedat450C/Cswithcoverflashingsealed.Simpleconstructionthathasbeenwellmanagedandwouldattractascoreofatleasta5–ifitwasonalargescalearoundabuildingandalltothisstandard,thena6wouldbemerited.

Furthermore,thecaretakentomakethesedistinctivestructureslookaestheticallypleasing,whateverthedesign,willcatchtheeyeofthejudges.Neatdetailsaroundfixingstothemainsuperstructureelementsalongwithcarefulconsiderationtotheprovisionandmaintenanceofbalconydrainageandoverflowsystemswillensureyoudemonstrateyourtechnicalexpertise.Effortsmadetocreateapleasingappearancetosoffitsanddeckingwillensurehighermarksareawardedbythejudges.


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3.9 FIRE STOPPING AND SOUND PROOFING

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3.9 FIRE STOPPING AND SOUND PROOFING

Images 32 and 33:Firestoppingandsoundproofingarecriticalelementsrelatingtothesafefunctionofthebuilding.Thecorrectinstallationoffireandsound-resistingmaterialstowalls,ceilingsandcompartmentsisvitallyimportanttoachievetheirrequiredperformancestandards.

Careshouldbetakentoensurethatproductsareinstalledaccuratelyandpreciselytomeettheirperformancecapabilities.

Cataloguedphotographicrecordsofworkmanshippriortocoveringuparenowbecomingusualpracticeonsite,asisengagingtheservicesofaspecialisedfireengineeringcompanytoaddressthefirestoppingaswellasmaintaininganonlinedatabaseofrecords.

Thejudgeswillbelookingforaccurateplacementoffirebarriersandforthebarriermaterialtobeprotectedwhererequiredfromsubsequentconstructionprocesses.Thefirebarriersshouldbeastightaspossibletotheelementsofstructurewithinwhichitisbeingheld–sonogapstoallowtheinadvertentpassageofsmokeorflamesshouldbeevident.

Theworkshownhereisverygoodandwellworthamarkof5–possiblya6ifconsistentatthislevelacrossthesite.


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GOOD LUCK!


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R387 02/21

Wehopeyouhavefoundthisbestpracticeguideusefulingainingabetterunderstandingofwhatthejudgesarelookingforateachstageofconstruction.

Remember,thesixcharacteristicsthejudgesarelookingforinasitemanagerare:

■ Consistency

■ Attentiontodetail

■ Technicalexpertise

■ Leadership

■ Interpretation

■ HealthandSafety

WewishyoualltheverybestinthePrideintheJobcompetitionasyoustriveeitherforyourveryfirstwinortorepeatorimproveonyourperformanceinpreviousyears.

best practice section 3 guides superstructure

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