Northwest Foam Products, Inc. EPS Specs
Physical Properties of Expanded Polystyrene (EPS)
Federal Specifications: ASTM C 578-92
Minimum and maximum allowable values.
| Property | Units | ASTM Test | Type I | Type VIII | Type II | Type IX | |
| Density, Nominal | pcf | C303 or D1622 | 1.00# | 1.25# | 1.50# | 2.00# | |
| Density, Minimum | pcf | C303 or D1622 | 0.90 | 1.15 | 1.35 | 1.80 | |
| Density, Range | pcf | C303 or D1622 | 0.90-1.14 | 1.15-1.34 | 1.35-1.79 | 1.80-2.20 | |
| Thermal Conductivity K Factor | @ 25° F | BTU/(hr) (sq.ft.)(F/in) | C177 or C518 | 0.23 | 0.22 | 0.21 | 0.20 |
| Thermal Conductivity K Factor | @ 40° F | BTU/(hr) (sq.ft.)(F/in) | C177 or C518 | 0.24 | 0.235 | 0.22 | 0.21 |
| Thermal Conductivity K Factor | @ 75° F | BTU/(hr) (sq.ft.)(F/in) | C177 or C518 | 0.26 | 0.255 | 0.24 | 0.23 |
| Thermal Resistance R-value* | @ 25° F | at 1 inch thickness | - | 4.35 | 4.54 | 4.76 | 5.00 |
| Thermal Resistance R-value* | @ 40° F | at 1 inch thickness | - | 4.17 | 4.25 | 4.55 | 4.76 |
| Thermal Resistance R-value* | @ 75° F | at 1 inch thickness | - | 3.85 | 3.92 | 4.17 | 4.35 |
| Compressive 10% Deformation | psi | D1621 | 10-14 | 13-18 | 15-21 | 25-33 | |
| Flexural Strength | psi | C203 | 25-30 | 30-38 | 40-50 | 50-75 | |
| Tensile Strength | psi | D1623 | 16-20 | 17-21 | 18-22 | 23-27 | |
| Shear Strength | psi | - | 18-22 | 23-25 | 26-32 | 33-37 | |
| Shear Modulus | psi | - | 280-320 | 370-410 | 460-500 | 600-640 | |
| Modulus of Elasticity | psi | - | 180-220 | 250-310 | 320-360 | 460-500 | |
| Water Absorption | % | C272 | < 4.0% | < 3.0% | < 3.0% | < 2.0% | |
| Water Vapor Transmission | Perm. In | E96 | 2.0-5.0 | 1.5-3.5 | 1.0-3.5 | 0.6-2.0 |
*R-value means the resistance to heat flow. The higher the R-value, the greater the resistance to heat flow. Typical tested R-values are based on the data provided by Nova Chemical Co., BASF Corp., and Huntsman Chemical Company.
Additional Information on All Types
- Maximum Service Temperature: Long Term Exposure 167 degrees Fahrenheit, Intermittent Exposure 180 degrees Fahrenheit
- Oxygen Index: ASTM test D2863 = 24.0%
- Coefficient of Thermal Expansion: ASTM Test D 696 = 0.000035in./(in.)(F)
- Buoyancy-Flotation: Minimum 50lbs / Cubic Foot
- Capillarity – None
- Long Term Exposure 167° F, Intermittent Exposure 180° F
- ASTM Test D 2863 = 24.0%
- ASTM Test D 696 = 0.000035in./(in.)(F)
- Minimum 50lbs / Cubic Foot
Building Code Classification
ICC ESR-1349
U.L. File #R12290 Control #85TO Classification BRYX
Flammability Warning
Expanded Polystyrene (EPS) materials sold for construction use have a fire retardant modifier, but are considered combustible, as are all organic materials. They must not be stored or installed near open flame or any other source of ignition. In addition, when EPS insulation board is installed in the interior of a structure, it must be protected by a proper thermal barrier, and the installer must review applicable local, state, and federal building codes to determine the correct thermal barrier for the particular application.
Adjoining Materials Warning
Expanded Polystyrene (EPS) is subject to attack by liquid solvent or some solvent base adhesives and other liquid products such as gas, diesel, etc. Care should also be taken to separate any coal tar pitch products or coal tar pitch vapors from any direct contact with EPS foam.