Type IX EPS Technical Data

Strength for Heavy-Duty Applications

The strength of our Type IX EPS comes from its higher density. With a compressive resistance of 25 psi, this material is specifically designed to handle substantial loads without compromising its structural integrity or insulating properties. This makes it the ideal choice for installations under concrete slabs, in foundation walls and in commercial roofing systems where it provides a stable, firm base that resists deformation over the life of the structure.

Improved Moisture Management

Like all grades of EPS, Type IX EPS features a closed-cell structure that provides excellent moisture resistance, helping to prevent mold growth and contributing to a healthier building environment. Its very low water absorption rate of less than 2.0% by volume means it will retain its thermal performance and dimensional stability even in damp conditions common to below-grade applications. While EPS is not a vapor barrier, its structure allows it to “breathe,” which can help prevent moisture accumulation within wall assemblies. This breathability eliminates the need for costly venting that other insulation materials might require.

Fire Safety and Flammability

Like many construction materials used in building envelopes, EPS is combustible and should be installed with all appropriate safeguards as required by local building codes. The Oxygen Index test measures the minimum oxygen level needed for a material to burn under controlled lab conditions.

Important Safety Note: This test does not indicate how the material will perform in a real fire. When exposed to high heat, EPS will not continue to burn on its own; it will melt away. For safe use, it is essential that the installation includes proper protection, such as a thermal barrier, separating the insulation from the building’s interior.

Long-Term Stability and Protection

To maintain its integrity and performance, EPS should be covered or finished when prolonged exposure to sunlight is expected, as ultraviolet (UV) radiation can cause surface dusting or discoloration. While EPS performs well across a broad temperature range, it is also important to note that it may experience dimensional changes when continuously exposed to temperatures above its maximum recommended long-term exposure temperature of 167°F. In roofing and other exterior applications, this is managed with the use of appropriate coverings or membranes.