b'Pavers (Ballast) Filter layer /Water flow resisting layer (optional) Insulation Drainage layer (optional) Roofing Membrane Structural Deck PMRA Figure 2: Flow diagram showing long-term cycling (LTC) procedure.obtained from three different sources Pride, Quality, or manufacturers: S1, S2 and S3. Three Innovation, compressivestrengthsofXPSwere Performance tested: 35 psi (241 kPa), 40 psi (276 kPa) & Safety.and60psi(414kPa).Severalofthe Its who we are, products tested had a drainage channel Its what we do. at the bottom, and some had grooves in the top of the insulation boards. In addition, as a means to better predict the water absorption in roofing assem-blies as opposed to individual insulation boards, some specimens were tested in stacks of two or more insulation boards as to better represent design assemblies P: 250.336.8088|Toll Free: 1.888.318.8642 as constructed.www.nelsonroofing.com ce-IndevelopingPMRAtestprocontact@nelsonroofing.com durestodeterminethelong-term moistureadjustmentfactor(U ), LTCComox Valley - Campbell River - Powell River | Covering Vancouver Island & Sunshine Coast for 45 years two primary mechanisms of moistureingress into the insulation were consid-ered: water immersion (WI) and water vapour diffusion (WVD). For the WI mechanism, both full and partial immer-Page 1 of 4 siontestswerecarriedoutinaccor-dancewiththeproceduresoutlined in ISO 16535. In parallel, to evaluate moisture transfer due to vapour move-ment, testing was conducted following ISO 16536, which outlines the proce-dure for WVD.Beyondtheseindividualmech-anisms,theeffectsoffreeze-thaw (FT)cyclingacriticalfactorin coldclimateapplicationswerealso incorporated.Amodifiedversionof ASTMC152wasusedtosimulate repeatedcyclesofwetting,freezing anddrying,replicatingreal-worldenvironmental stressors.Recognizingtheneedforamore integratedevaluation,anewlong-20 lROOFINGBClFALL 2025'