The Polyisocyanurate Insulation Manufacturers Association and the National Roofing Contractors Association announced the publication of a 2001 edition of ASTM C1289, Standard Specification for Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board. The major changes in the new edition are directed to polyiso products intended for use as roof insulation. These products are identified in the standard as Type II. Type II Class 1 products are those with fibrous felt or glass fiber mat facers, commonly used in the U.S. roofing industry. These products are further identified based on their compressive strength: Grade 1 (16 psi). Grade 2 (20 psi) or Grade 3. Type II Class 2 products are also used in roofing.
Another change that was initiated to better characterize currently available polyiso roof insulation was linear dimensional stability. For Type II polyiso roof insulation, the new performance standard for length and width dimensional change is a maximum of 2 percent. Also, ASTM C 1303, a new method for determining and reporting long-term estimates of R value, has been added as a voluntary option for describing Type II product performance.
PIMA also recently unveiled a new technical bulletin on tapered roof insulation systems. Technical Bulletin 108 highlights the advantages of using tapered polyiso insulation, including its ability to reduce or eliminate the amount of ponding/standing water on the membrane when the roof deck does not provide adequate slope, design considerations and the secondary application of insulation crickets.