Intumescent coatings are paint like coatings that are applied to structural steel members. The final thickness of these coatings typically ranges from 0.03 inches to 0.50 inches. Intumescent coatings contain a carbonic, viz. a polyhydric, source of carbon such as starch or penta erythritol, which is rich in carbon and tends to form a charred foam on heating. This must be used in conjunction with a source of phosphoric acid, of which mono ammonium phosphate has been claimed as being particularly effective. The foam formed on commencement of combustion, acts as an insulator for the substrate. This insulating barrier is necessary to ensure the structural performance of the steel members at the temperatures anticipated during a fully developed fire. For intumescent coatings to provide this insulating barrier to the structural steel, two unique characteristics of the coating must be considered, coating expansion and retention of a char layer.

Intumescent fire barrier is heavy-bodied, single-part latex. It is designed for use on construction materials such as oriented strand board, structural insulated panels, framing lumber, plywood, trusses, drywall and doors. It is also be used on aluminum and steel sheets, round and box steel columns.