Reaction to fire

Following the European classification sytem, building materials are divided into 7 Euroclasses:

A1 and A2 for inorganic, non combustible materials
B, C, D, E, for combustible materials
F, for materials where performance has not been determined

Polyurethane rigid insulation reaches a classification from B to E in reaction to fire, depending on a number of factors such as formulation and type of facings.

Additionnal classifications are used as an indication of the smoke production for building materials: s1, s2 and s3 where in the case of s3 there is no restriction on the smoke production.

Polyurethane rigid insulation reaches a classification from s1 till s3 for smoke development, also depending on the formulation, the type of facings...

Additional classifications are for burning droplets/particles for building materials: d0, d1 and d2.

PUR rigid insulation is a thermoset, which means that it does not melt under the effects of fire. It does not produce droplets. It is therefore always classified d0.

Continuous glowing

Rigid foam does not support continuous glowing, and so poses no threat from this source of fire.

Continuous glowing combustion is a self-propagating combustion process without flaming that may occur inside certain porous materials for example fibrous insulation products and fibre boards. With these products heat build up internally occurs due to the continuing exothermic processes initiated by the original exposure to an ignition source. This heat build-up may cease with time if the insulation allows the excessive heat to escape. If not, the process continues with the temperature continuing to rise within the product eventually thereby causing ignition of the product.

Insulation products are usually installed behind interior room linings and in cavities behind large surface areas. Continuous glowing combustion fires occurring within the insulation develop slowly and therefore pose a risk because they might remain undetected behind the lining product for a long period of time (up to several hours). Thus these products possibly act as an ignition source with a large-area for adjacent products/items resulting in a developing flaming fire.

Polyurethane rigid insulation does not initiate continuous glowing, therefore it does not propagate fire.