Faced rigid board polyisocyanurate insulation is the most
popular type of insulation used in low-slope roof systems in the
U.S. However, the product's ASTM International standard is
confusing and cumbersome, which often results in inadequate or
improper specifications. If you are involved with specifying or
installing polyisocyanurate insulation, you should be aware of
The U.S. product standard for faced rigid board polyisocyanurate
insulation is ASTM C1289, "Standard Specification for Faced Rigid
Cellular Polyisocyanurate Thermal Insulation Board."
ASTM C1289 is divided into seven types identified as Types I
through VII. Type I products are faced with aluminum foil and
typically are used in wall sheathing applications. Type II products
are faced with mat facers and typically are used in low-slope roof
systems. Types III through VII products include composite-type
polyisocyanurate boards laminated with perlite board, wood
fiberboard, oriented strand board, wafer board or glass mat-faced
gypsum board and often are...
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