Intumescent coatings are used to maintain the stability and integrity of structural steel work for up to 2 hours. They are by airless spray in thicknesses of between 400 and 8000 microns depending on the degree of protection required, the size and weight of section and the portion of section exposed to fire (referred to as the Hp/a).

Under the influence of heat the intumescent coating expands by up to 50 times to produce a charred insulating layer. Intumescent coatings are also used to improve the flame retardant qualities of combustible materials e.g. timber.