THERMAX Sheathing
| 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
Complies with ASTM C 1289 Type I, Class 2. Meets IBC/IRC requirements for foam plastic insulation. See NER-681, UL 1256 – see UL Directory, FM 4880 – see Factory Mutual Approval Guide.
**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 (5% for STYROFOAM PLAZAMATE insulation and for STYROFOAM HIGHLOAD 40, 60 and 100 insulation products) or at yield, whichever occurs first. Since STYROFOAM extruded polystyrene and Dow polyisocyanurate insulation products are visco-elastic materials, 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.
3 R-value determined by ASTM C518.
