Thermax Sheathing (Foil Finish), 1 in, 4'x8' Sheet, R 6.5

DOW 268433
Product sold by bundle. To Order Call 888-223-3050
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THERMAX™ Sheathing is a nonstructural, rigid board insulation consisting of a glass-fiber-infused polyisocyanurate foam core laminated between two 1.0 mil, smooth, reflective aluminum facers. The glass-fiber reinforcement contributes to improved fire performance and dimensional stability. THERMAX™ Sheathing can be installed exposed to the interior without a thermal barrier and offers high, long-term R-value. Used in conjunction with the appropriate joint closure system, THERMAX™ Sheathing with its low perm rating reduces moisture condensation within and behind the insulation. Thermax Foil Sheathing gives you a semi-finished surface with the added benefits of a closed cell insulating board.


  • Thickness: 1 inch
  • Sheet Size: 4' x 8'
  • R Value: 6.5
  • Surface Finish: Foil/Foil
  • 21 Pieces per Bundle
  • Minimum Order: 16 Bundles

Panels can be glued to most wall surfaces using Great Stuff Wall & Floor Adhesive or Great Stuff Enerfoam. Once Panels are fastened, use matching Thermax Foil Tape to cover seams to give a finished look and reduce air infiltration.  For even better leak protection use Great Stuff Gaps & Cracks to fill between panels and seal openings.

Want to get adhesive foam and tape in one package. Take a look at our Thermax Installation Kit.

Additional Sizes

We stock additional sizes of Thermax. Follow the links for pricing and information.

White Finish: 1"x4'x8', 1.55"x4'x8', 1.55"x4'x9', and 2"x4'x8'

Foil Sheathing: 1/2", 1.55" and 2"

We can special order even more sizes. Please contact us for details.

THERMAX™ Sheathing is

  • Specially designed to have a Class A fire rating and can be used in a range of concealed and exposed applications, above and below grade, and can be used in exterior walls. Because of its improved fire performance, THERMAX™ Sheathing is especially appropriate for hourly rated assemblies.
  • Approved for use, per Section 2603.5 of the International Building Code, in Exterior Walls of Types I,II,III and IV construction. THERMAX™ Sheathing is designed for use as continuous insulation in both interior and exterior applications to assist in meeting and exceeding both the most current IECC and the ASHRAE 90.1 energy standards. Maximum length is 30 ft. (9.1 m) and maximum thickness is 4.25" (108 mm).


Prices quoted are for delivery from factory. Minimum quantities and delivery charges may apply. Please contact us for delivery costs. Additional charges may apply if shipping to a residence, extended service area, or business that does not have a loading dock.

Questions? - Call us at 888-223-3050

2 Reviews

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  • 5
    Damaged Product

    Posted by David Jaxheimer on Dec 2nd 2014

    Product was received with damage to 4 sheets. Warehouse employee was extremely helpful and knowledgeable regarding the Thermax board. Great customer service regarding the sale, however product was damaged

  • 4
    Extremely helpful warehouse employees

    Posted by Unknown on Sep 12th 2014

    The product was exactly as advertised, though somewhat difficult to cut. However, the employees at the warehouse were incredibly helpful, answered all my questions, and helped strap the product to my car. They also declined any gratuity for their assistance.