Maintaining shape and constant dimensions over very long periods of time are key requirements for insulating materials, particularly when they are exposed to considerable variations in temperature (for example on roofs, which can be exposed to both sun and snow within a short period of time).
Because of its thermoset structure, polyurethane exhibits excellent dimensional stability.
Depending on the density and type of facings, rigid polyurethane insulation for building applications can be used long-term over a temperature range of -30 °C to +90 °C.
PUR/PIR rigid insulation materials can withstand temperatures of up to 250 °C for short periods with no adverse effects. PUR/PIR rigid insulation with mineral fleece facings or without facings is resistant to hot bitumen and can be used in flat roofing sealed with bituminous roof covering.
Furthermore, a number of special polyurethane products can be installed as insulation under poured-asphalt floor screed and can withstand temperatures of +200 °C without additional heat protection, or can be used for cold-temperature applications down to -180 °C.