The ability of the element of construction to withstand fire exposure on one side only, so as to reduce the probability of the transmission of fire as a result of significant radiated heat either through the element or from its unexposed surface to adjacent materials.
Pilkington Pyrodur® is the product line with a range of products that do provide some protection from radiation because they comprise intumescent interlayers which become opaque in a fire. The period depends on the grade of product. Radiation is measured for fire tests performed in accordance to the European Standards.