2.5 lb/ft³ (40 kg/m³) density ISO-C1/2.5 is Dyplast Products’ 2.5 lb/ft³ polyisocyanurate rigid, closed cell, foam insulation.Click to see full answer. Simply so, how much does rigid insulation weigh?Rigid Roof Insulation Weight. ASCE states that rigid roof insulation weighs 1.5 psf per inch of thickness, whereas, polyiso insulation, like Thermax, is < 0.25psf per inch.Also Know, how heavy is a roof? The dead load on a roof is the weight of the roof structure itself, along with any permanently attached materials or structures on the roof, so it must be designed, first of all, to support itself. The dead load of a typical asphalt-shingled, wood-framed roof is about 15 pounds per square foot. In this way, what is the R value of polyisocyanurate insulation? of polyisocyanurate insulation. The manufacturers of the products all reported an LTTR of R-25 (RSI-2.13) for a single, 4 in. (102 mm) thick piece of polyisocyanurate insulation; however, BSC tested a double 2 in. (51 mm) layer so the appropriate LTTR is 2 x 12.1 = R-24.2 (RSI-4.26).How much does rubber roofing weigh?After combining the weight of components (i.e. insulation, membrane, fasteners, and adhesive), typical installation weight is less than 2 pounds per square foot (10 kg per square meter) when . 060″ thick membrane (typically weighing 1/3 pound per square foot or 1.6 kg per square meter) is utilized.