DuPont™ Thermax™ Heavy Duty Foam Insulation

Commercial | Residential | Multifamily | Wall

Made for high durability in difficult conditions

As an insulation and interior finish system for walls and ceilings, Thermax™ Heavy Duty Insulation stands up to the elements with a fiberglass core and thermoset-coated aluminum facing.


DuPont™ Thermax™ Heavy Duty Foam Insulation

Thermax™ Heavy Duty Insulation* is designed as an insulation and interior finish system for walls and ceilings in metal, wood post frame, and concrete or masonry buildings, as governed by building codes. Thermax™ Heavy Duty consists of a glass-fiber-reinforced polyisocyanurate foam core faced with nominal 4 mil embossed white thermoset-coated aluminum on one side and 1.25 mil embossed aluminum on the other. The tough 4 mil white embossed aluminum surface makes it a durable insulation/finish choice for use in moderate-impact areas, and it can be pressure washed up to 2,000 psi with a 15-degree or greater spray tip (at 3’ minimum distance). Thermax™ Heavy Duty also offers high, long-term thermal resistance, with facers that help prevent water and water vapor intrusion into the insulation foam allowing it to stabilize at a higher R-value*. Used in conjunction with the appropriate joint closure system for the application, Thermax™ Heavy Duty – with its low perm rating – can help to reduce moisture condensation within and behind the insulation.

* Thermax™ Heavy Duty Insulation is a former product of The Dow Chemical Company


Features & benefits

Feature Benefit
Easy to cut, handle, and install
  • Easy to use
  • Moisture Resistant
  • Reduces the potential for condensation within the wall assembly

    Physical properties

    Method Unit Value
    Compressive Strength1 ASTM D1621 psi, min. 25
    Water Absorption ASTM C209 % by volume, max. 0.1
    Water Vapor Permeance ASTM E96 perm, max <0.03
    Maximum Use Temperature - °F 250
    Flexural Strength ASTM C203 psi, min. 55
    Light Reflectance, Visual Light Spectrophotometer - % 65

    1 Vertical compressive strength is measured at 10 percent deformation or at yield, whichever occurs first


    Available sizes


    Thickness (in.) R-Value Board Size (ft.) Edge Treatment
    0.625 4.1 4 x 8, 4 x 12 Square Edge
    1.0 6.5 4 x 8, 4 x 12 Square Edge
    1.55 10.1 4 x 8, 4 x 12 Shiplap
    2.0 13.0 4 x 8, 4 x 12 Shiplap