Polyisocyanurate insulation widely is used in low-slope roof
systems and sometimes as a component of steep-slope roof
assemblies. Specifying the correct type of polyisocyanurate
insulation for a specific application is an important design
consideration for ensuring long-term roof system performance.
Following are descriptions of various types of polyisocyanurate
The current recognized U.S. product standard for faced
polyisocyanurate insulation is ASTM C1289-06, "Standard
Specification for Faced Rigid Cellular Polyisocyanurate Thermal
Insulation Board." Within this standard, there are six type
classifications, several of which are further divided into classes.
And three classes are further subdivided into grades. Overall, the
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