b'T&R Updateroofing industry to use water based adhesives asbar graph with these results.the allowable VOC levels are now dipping belowAfter observing this lab mode of peel failure we 250 grams/liter, which is the level a low VOC isre-examined a series of photos of actual roof failures currently at.Water based adhesives (WBA) cannotthat involved WBA.It was obvious that paper be allowed to freeze; they generally need to be storedfacer delamination was a major player in loss of in a temperature controlled environment 60 - 90membrane attachment due to moisture building up F, plus or minus.Pails of WBA have a date stamp;in the WBA.It was generally not the WBA material this means they have shelf life.One top of all thesefailing from rewetting itself but some photos did The MRCA is thereforeshow a WBA moisture reversion problem along with recommending that all roof systems using WBA use polyiso boards with coated glass facersrestrictions, WBA materials need more open time to dry down in cold damp weather as they do on warm, very humid days.As the MRCA T &R and NRCA TOC Committees wrestled with this, our lab research has shown that if water vapor content within the roof system builds up, water based adhesives reabsorb the moisture and surprisingly held on to it while maintaining some peel strength.We conducted peel strength test on 060 EPDM and 060 PVC with different WBA products.The 3 day and 7 day peel strengths ranged a low of 0.5 pounds per lineal inch (PLI) to 3.3 PLI for EPDM Figure 3 Roof top photo of loss of membrane attachment due to low level moisture build up being held in WBAmembrane detachment.Figure 3 is a field photo of a TPO membrane which lost adhesion at two years of age.By inspection, it is mostly a cohesive failure within the paper facer.The MRCA is therefore recommending that all roof systems using WBA use polyiso boards with coated glass facers, similar to that recommended for Figure 2 Bar graph showing predominant delamination of paper facer usingroof system construction over new concrete decks.WBA bonding adhesive The MRCA is aware of other studies on the moisture effects of polyiso facers being conducted by other bonded to paper faced polyiso and from 0.2 to 1.6associations and we look forward to seeing the PLI for 060 PVC bonded to paper faced polyiso.Aresults of those studies.similar result occurred with those samples oven dried at 104F for 3 days.However, the predominantRene Dupuis, PhD PE, of SRI in Middleton, WI, can be reached at mode of peel failure was within the facer reinforcedRDupuis@sri-engineering.com. Dupuis serves on MRCAs Technical paper facer of the polyiso board.Figure 2 shows aand Research Committee.www.mrca.orgMidwest Roofer 17'