Making a door resistant to fire can add important time for people to escape from home fire emergencies. Two ways of making doors fire resistant exist. The first way is to coat the surface with a protective resin or carbon-based chemical that lowers its ignitability. The second way is to immerse the entire door in a mineral-based solution so tht the entire door is changed in composition.

The coating method requires a liquid agent known as an intumescent. Older intumescents and endothermic resins, where endothermic means heat-absorbing, have become disused due to the excessive smoke they produce when challenged with great heat. But lighter intumescents continue to be used.

Intumescents cannot hold off a fire from a door forever but merely retard flames and increase the time it takes for the door to ignite. They are applied as a thick coat in the manner of paint onto the surface of the door. Exposure to excess moisture and constant heat is discouraged to protect the efficacy of these agents.

The second way of fire proofing is to soak the entire door, as long as it is not yet painted and finished, into a solution. Commonly ammonium or zinc salts are used. After soaking and drying these woods become highly impervious to heat. However, the second method is much more labor intensive than the first.

A very new kind of door is the fiberglass door. Strands of glass are bonded with a resin-like compound in a door-shaped mold. The finished product is a door that’s solidly constructed with hardened glass but still contains the flexibility of resin.

The surface of fiberglass may be made to appear like traditional wooden doors, but without the downsides of warp-age and cracking. Fiberglass doors, being so long-lasting, also provide extended warranties lasting up to 30 years. One drawback is that fiberglass doors are difficult to fix except for the most minor of problems.