Why it is important

These are gypsum-based, plaster-like coatings that look like white stucco when dried. These coatings are sprayed on the surface of the structural members that need protection. They are usually used to keep girders and beams below 540 C, where the steel will bend. The coatings are also used to protect structural concrete, such as in vehicular tunnels, from petroleum and other intense fires. Concrete members need extra fire insulation to preserve their structural integrity.

Intumescent paints expand and char when heated to form a heat resistant barrier. It can give up to 120 minutes fire protection. They usually contain sodium silicates. The final thickness of these coatings typically ranges from 0.03 inches to 0.50 inches. The coatings are designed to provide insulation to the steel in the event of fire. The paint coating thickens, entraining air and forming a char layer, providing greater insulation under high-heat conditions. These coatings are sprayed or brushed onto the surfaces to be protected. While there is some interchangeability with the cementitious coatings, these paints are usually used on pipes and other metallic items like tanks and valves, where the rough-thick coating of cementitious fireproofing would be difficult.