The integral, durable facer of THERMAX™ (ci) Exterior Insulation provides a drainage plane and water-resistive barrier, eliminating the extra step of installing a membrane or building wrap. The lightweight polyisocyanurate foam core provides one of the highest R-values available (R-6.5 at 1") for long-term thermal performance.
For best results, seal joints with WEATHERMATE™ Straight Flashing.
Building Code Compliance
Complies with ASTM C1289 Type I, Class 2. Meets IBC/IRC requirements for foam plastic insulation. See ICC-ES ESR-1659. FM 4880 - see Factory Mutual Approval Guide. UL Classified, see Classification Certificate 1256. Calif. Std. Reg. # CA T383.
|Nominal Board Thickness(1), in||R-Value(2)(3)||Board Size, ft||Edge Treatment||Min Compressive Strength(4), psi|
|.625||4.1||4' x 8' / 4' x 12'||Square Edge||25|
|1.0||6.5||4' x 8' / 4' x 12'||Square Edge||25|
|1.55||10.1||4' x 8' / 4' x 12'||Shiplap||25|
|2.0||13.0||4' x 8' / 4' x 12'||Shiplap||25|
(1) Not all product sizes are available in all regions.
(2) R means resistance to heat flow. The higher the R-value, the greater the insulating power. R-values are expressed in ft2• h•°F/Btu. R-value determined by ASTM C518.
(3) Consult your Dow Seller or Technical Service Group for information on different R-values.
(4) Vertical compressive strength is measured at 10% deformation or yield, whichever occurs first. Since Dow polyisocyanurate insulation is a visco-elastic material, adequate design safety factors should be used to prevent long-term creep. For static loads, 3:1 is suggested. For dynamic loads, 5:1 is suggested.
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