Fire tests have shown that Koemmerling uPVC materials, being naturally flame retardant throughout their product life, will not cause, support or enhance the development of accidental fire. Unlike timber windows, the uPVC sections do not support combustion and are in fact self-extinguishing. This quality prevents the promotion of fire spread. For this reason, Koemmerling window systems offer considerable fire protection. The special profile compound fulfils Class 1 fire resistance (i.e. most resistant) as defined in BS (British Standards) 476: Part 7. Therefore, Koemmerling profiles are an effective means for preventive fire protection.