Vicwest AWIP R-value
I'm insulating using foam from factory rejects of Vicwest AWIP roof panels. They are ridiculously cheap (7 cents per board foot) and the seller claims an R value per inch of 7.5
According to the manufacturer's specs, the panels are injection moulded polyisocyanurate and R per inch is 7.9 at 40F and 7.1 at 75F. This contradicts research cited here that polyiso loses R value with colder temperatures and starts around R6/inch. Vicwest seems to have the temperature coefficient backwards.
Is there something different about the way these panels are manufactured that pumps up the R value and changes behaviour in cold temperatures? Have they cheated the laws of physics or is this just false advertising?
What R value per inch should I assume as a design value? Climate zone is 5B so it is a low temperature application.
Posted Tue, 02/11/2014 - 16:53
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