What temperature range can Isolon and Warmlex foams withstand in real applications?

In most applications Isolon and Warmlex PE foams work reliably in a moderate temperature range, but they are not high-temperature insulation or fire protection materials.

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This article explains how Isolon 300/500 (crosslinked IXPE/XPE), Warmlex (non-crosslinked EPE) and foil-laminated versions behave at elevated and low temperatures, and what to consider in EU projects.

General temperature behaviour of PE foam

Polyethylene foams have the following typical characteristics:

• at low temperatures they remain elastic within a certain range, but can become stiffer;
• at elevated temperatures the material softens and may lose stiffness;
• prolonged exposure to high heat accelerates ageing and deformation;
• direct contact with very hot surfaces or open flame is not allowed.

For many building and technical uses the foam is installed inside constructions (under screed, under floor coverings, behind cladding), which reduces direct thermal stress.

Foil-laminated foam and hot surfaces

Foil-laminated Isolon is often used where reflective function is required (for example, behind radiators, in roof constructions, around ducts). In such cases:

• metalised or foil layer reflects part of radiant heat;
• the foam core must still be protected from direct contact with high-temperature elements;
• local overheating (for example, directly against a flue or exhaust pipe) is not acceptable.

Design considerations for EU projects

When using Isolon and Warmlex in constructions exposed to temperature variations, we recommend:

— placing the foam inside the construction, not directly on hot surfaces;
— avoiding continuous exposure to very high temperatures;
— considering UV protection if used near glazed or outdoor areas;
— combining with other insulation materials where required by standards.

Frequently asked questions

• Can I use foil-laminated foam directly behind a radiator? Usually it is installed on the wall behind the radiator, not in direct contact with very hot metal parts. Final design must follow local building codes.
• Does the foam work in unheated spaces? Yes, but stiffness can increase at low temperatures. Mechanical design should take this into account.