b'Polyisocyanurate Insulationprovided insight into the knowledge gap and confirmed additional research is needed to correlate the effects of aging with the laboratory The focus of the comparison was not to identify the manufacturers or thepredictions and requirements in the current standards.blowing agents of the samples, but to investigate the insulation performancePrevious StudiesFor example, in 2006, NRCA conducted a limited study on the aging of polyisocyanurate insulation. The study, conducted as a generic component independent of manufacturer details.withtheCanadianRoofingContractorsAssociationandEx-truded Polystyrene Foam Association, consisted of 20 specimens that were aged naturally in laboratory conditions for less than five years. The study found 17 of the tested specimens exhibited R-values less than their established LTTR values, demonstrating LTTR methodology appears to overestimate a products actual R-value at five years of relative aging.In2009,afield-monitoringstudywasconductedbyRDH Building Science Inc., Vancouver, in collaboration with the Roof-ing Contractors Association of British Columbia to obtain infor-mation regarding concerns of aging polyisocyanurate insulation. A building was set up to record the temperature dependent con-ductivity of the insulation over 5 years. The in-service results were compared with samples that were aged naturally in labora-tory conditions at 72 F. The study concluded in-service aged poly-isocyanurate insulation measured less thermal resistance than lab-aged polyisocyanurate insulation.Another study was completed by RDH Building Science in 2015,duringwhichthree-year-oldpolyisocyanuratespecimens were removed from the roof of a building in British Columbia and tested in a laboratory. The in-service aged results were com-pared with the same insulation tested when it was a new mate-rial, and it was determined the aged insulation had a significantly reduced R-valueup to 25 per cent at low mean temperatures compared with the new insulationdemonstrating the effects of the initial aging on the materials performance.These limited studies confirmed additional investigation is need-ed to correlate the effect of aging with the predictions and require-ments in current standards. Furthermore, additional exploration of in-service aging through exposure to typical climatic events in roof assemblies is required to gain a better understanding of the effects of in-service conditions on polyisocyanurate thermal performance. Additionalproperties,suchascompressivestrengthandflexural strength, also require investigation to determine the effect of aging on the critical mechanical properties of polyisocyanurate insulation.New StudyTo validate and further continue the research of earlier studies, the National Research Council Canada (NRC) is conducting a study to quantify the effects of aging on thermal insulation ma-terials. The study supports NRCs ongoing initiative of climate resiliency and adaptation of building envelope materials and de-signs. The study involves collecting in-service polyisocyanurate samples and will be further expanded to other common roof in-sulations. We have some experimental data from the analysis of thermal and mechanical properties of aged polyisocyanurate in-sulation boards and can provide a relative comparison with code and standard minimum requirements.NRC obtained polyisocyanurate samples from 16 roofs that were being retrofitted or re-covered. The samples were collect-ed from buildings with variable occupancy in New Brunswick, Ontario and Qubec. The exposure period ranged from 13 to 31 years. The 16 roof insulation samples were a combination of one-layer boards, two-layer adhered boards and insulation boards with adhered cover boards.Excluding the boards from the third category, 11 samples were investigated. The samples, their years of installation and occupan-cy types are in Figure 1. The samples were grouped according to ASHRAE climatic zones, based on the locations of their buildings.Allthecollectedinsulationboardshadorganicfeltfacers that fall into the category of Type II, except sample 12, which was Type I with an aluminum facer. This classification is based on ASTM C1289, Standard Specification for Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board.10ONTARIO ROOFING NEWSISSUE 1 2020 THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN'