THERMAX Sheathing
THERMAX™ Product Information Sheet (167KB PDF)
Installing THERMAX – Interior Basement Walls
Installing THERMAX – Closed Crawlspace (127KB PDF)
THERMAX™ sheathing is a glass-fiber-reinforced polyisocyanurate foam core with solid aluminum foil facers on both sides. Can be installed exposed to the interior without a thermal barrier.
Ease of application: Easy-to-handle THERMAX insulations require no special tools or materials for installation. Simply use a utility knife and a straight edge to cut the boards to size. Then adhere directly to basement walls with an approved adhesive.
For extra protection against air and moisture and a more finished appearance use one of the joint closure systems from Dow, or tape seams with THERMAX white foil tape or aluminum foil tape.
THERMAX insulations are backed with a 15-year limited thermal warranty.
| Nominal Board Thickness** |
R-Value3 |
Board Size |
Edge Treatment |
Min Compressive Strength† † |
| .5" |
3.3 |
16" x 96" / 108" / 120" |
Square Edge |
25 psi |
| .75" |
5 |
16" x 96" / 108" / 120" |
Square Edge |
25 psi |
| 1.0" |
6.5 |
16" x 96" / 108" / 120" |
Square Edge |
25 psi |
| 1.5" |
9.8 |
16" x 96" / 108" / 120" |
Square Edge |
25 psi |
| 1.75" |
11.4 |
24" x 96" / 108" / 120" |
Square Edge |
25 psi |
| 2.0" |
13 |
24" x 96" / 108" / 120" |
Square Edge |
25 psi |
| 2.5" |
15.8 |
24" x 96" / 108" / 120" |
Square Edge |
25 psi |
| 3.0" |
19 |
48" x 96" / 108" / 120" |
Square Edge |
25 psi |
| 3.5" |
22.1 |
48" x 96" / 108" / 120" |
Square Edge |
25 psi |
| 4.0" |
25.3 |
48" x 96" / 108" / 120" |
Square Edge |
25 psi |
Building Code Compliance Information
Complies with ASTM C 1289 Type I, Class 2. Meets IBC/IRC requirements for foam plastic insulation. See NES NER 681.
**Not all product sizes are available in all regions.
†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.
††Vertical compressive strength is measured at 10% deformation.
