Polyisocyanurate insulation — rip off?
Our radiant engineer strongly warned for the use of polyisocyanurate. I see that long term R-value ends up around 5.6. When this is true, why is this not mentioned on every page where polyisocyanurate use is mentioned… Our engineer REALLY dissed the product as he mentioned that the R-values decrease WITH temperature decrease. Exactly when you need it to work: it will NOT. “A total waste of money, stay away from it!” were his words. True or false? Simple styrofoam, when not used under slab, is just fine. Same R-5 per inch as Double Density…
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A collection of one thousand construction details organized by climate and house part