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Last Update: July 16, 2024

How Does ASTM C 1289 Classify Foam Insulation?


How does ASTM C 1289 classify foam insulation?


ASTM C 1289 is a standard developed by ASTM members that classifies the design requirements for a specific material, product, system and service. All faced rigid polyisocyanurate manufacturers are required to manufacture and test to the standards of ASTM C1289. This standard classifies faced polyiso panels by type, class, and grade.


Refers to the facer material that is bonded to the foam. Below is a list of common types of facers used in the commercial wall market.

Type Description
I Foil Facer
II Glass Mat Faced
V Plywood or OSB on one side, Fibrous Felt or Glass Mat on the other side.


For foil faced polyiso the “Class” designation refers to whether or not the foam core is glass fiber reinforced.

Class Description
1 Non-Reinforced Foam Core
2 Glass Fiber Reinforced Foam Core or Non-Reinforced Foam Core


For glass mat faced polyiso the “Class” designation refers to the material used in conjunction with the glass mat. Currently, all Type II polyiso products for commercial wall applications fall into the Class 2 category.

Class Description
2 Polymer Bonded Glass Fiber Mat both sides, Coated Glass
3 Glass Mat Only


Refers to the product’s compressive strength for permeable faced products. Compressive strength is reported in terms of PSI. Several polyiso products are available in multiple grades

Grade Description
1 16psi min
2 20psi min (Standard for most Xci products
3 25psi min