b'tilation strategies. Given these dif- ofthetownhouses,withtheOur investigations have identified that problems exist ferences, it is important that com- goalofidentifyingpotential mon walls are well constructed tomoisturesourcesintotheroof isolate the individual roof cavities.cavity.Theseinvestigationsre- with the ventilation of flat roofs and that research is Although an 18th-century city or- vealed minor deficiencies at the dinancegoverningtheconstruc- junctions of the fan casings with tionofcommonwallswasin- ducting and the polyethylene va- required to establish effective ventilation strategies.tended to limit the spread of fire,pour barriers within the master the isolation of roof cavities is alsobathroom. However, the lack of important to ensure that the ven- sealedductsforthereturn-air-tilation of one roof does not affecthandling system was the major theventilationofothers. 7 Thereasonformoisturemigration firstcasestudypresentedintheintotheroofcavity.Thislack next section illustrates this issue. ofsealedductsallowedhumidThe Blueprint Collective is Carlisles air to enter the wall cavities and Case Studies bypass the vapour barrier at thecomplimentary, white-glove service Recently, greater attention hashead of wall partitions. In addi-been paid to condensation prob- tion, the use of only top-mount- designed for select partners like you.lems and issues of mold growthed roof ventilators for the cavity within roof cavity spaces in newventilation created negative pres-ornewlyrenovatedbuildings.surization within the roof cavity Unfortunately,manydesignersunder normal conditions, which and builders place great faith inconsequentlydrewhumidair the building code with regard tofrom the interior space.flat-roof ventilation requirementsBasedontheseobservationsExclusive Bene ts:without giving due considerationandanalysis,theinvestigative to basic ventilation fundamentals.teamrecommendedlocalized Inaddition,giventhatcurrentrepairs at the master bathroom code requirements for roof venti- fan, as well as the installationSpeci cation lation are based on very limited re- of sealed ducts for the return- Reviewsearch, it is no surprise that prob- air-handlingsystemtolimit lematic situations arise. interiorhumidairfromby-Inthefollowingsections,wepassing the vapour barrier. Side describesomeprojectsinwhichinletportsbelowtheparapet our firm was called to assess issueslevelwererecommendedto of condensation or mold withinintroduce outside air into theCode attic spaces. roof cavity and resolve the issueAssistanceLaverdure of depressurization.InApril2017,ourfirmwasPrince-ArthurrequestedtoinvestigatearecentInMay2017,ourfirmin-accumulation of moisture withinvestigated the recent accumula-the shared roof cavity of attached,tion of moisture within the roof two-storey residential townhous- cavityofathree-storeycondo- Tailored esintheAhuntsicboroughofminiumbuildingneardown- Educational Montreal.TheconstructionoftownMontreal.ThebuildingSessionsthe buildings was completed thewas originally constructed in the year before our investigation, andearly 20th century and had been damages to the second-floor-levelretrofittedin2010.Similarto finisheswerereportedinspringthe Laverdure project, damage toBuilding 2017. An initial investigation ofthe interior finishes was reportedEnvelope the roof cavity via the removal ofat the upper-floor level (in thisConsultationtop-mounted roof ventilators re- case, the third floor). An initial vealed dampened roof insulationinvestigationoftheroofcavity anddarkenedwoodsurfacesonfound darkening of the under-the underside of the roof deck andside of the roof deck and on the the framing members. framing members.ThesharedroofcavityforDuringtheinitialvisit,the thesixpropertiescontained12investigativeteamremovedthe top-mounted six-blade roof ven- capping of roof-mounted duct-tilatorslocatedatquarter-pointsing enclosures to gain access toScan here to schedule from the end walls of each prop- the roof cavity and found an air erty. No side inlet ports or otherspace of only 3 in. (75 mm). Thea time to meet with a meansofintroducingfreshairroofventilationwaslimitedtoCarlisle expert.into the roof cavity were noted.twosingle-blade,roof-mount-Exhaustductsformechanicaledventilators.ventilationsystems(bathroomDuring our investigations, we fans, hoods, etc.) were evacuatednoted that a disconnected duct through the masonry walls. at one of the bathroom fan ex- Experience the Carlisle Difference|800-479-6832|www.carlislesyntec.comInMay2017,smoketracerhausts contributed largely to theCarlisle is a trademark of Carlisle.2024 Carlisle.investigationswereundertakenmoistureaccumulationwithin atthesecond-floorlevelofonetheroofcavity.Oncemoisture ORN THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ONTARIO ROOFING NEWSISSUE 1 202419'