Which type of fireproofing coating swells upon exposure to heat?

Intumescent coatings are designed to provide passive fire protection by swelling when exposed to high temperatures. This swelling creates a thick, insulating char that acts as a barrier against heat, effectively protecting the substrate underneath from reaching critical temperatures during a fire. This expansion increases the thickness of the coating significantly, which enhances its fire resistance properties.

In contrast, cementitious coatings provide fireproofing through a more rigid, cement-like material that does not swell but instead offers thermal insulation and impact resistance. Elastomeric coatings are flexible and primarily serve as protective layers against environmental conditions rather than functioning specifically as fireproofing. Polyurethane coatings are also not intended for fire protection; they are more focused on providing durability and chemical resistance rather than thermal insulation or fire resistance. Thus, the characteristic swelling of intumescent coatings makes them specifically effective for enhancing fire resistance in a variety of structures.