Gel-coatings are commercially available for use to protect buildings from wildfire. These can be used my fire-fighting professionals, or by the homeowner. When used by the homeowner, the gel product is intended to be applied to the exterior of the home (siding, windows, vents, decks) and even near by vegetation, prior to evacuation.

Gel coatings contain water adsorbent polymers (and when activated by water provide an insulating layer). These products can be sprayed on the exterior surfaces of your home prior to evacuating. Once applied, these coatings will lose effectiveness with time as they dry out, so how well it will work when the wildfire reached the building will depend in part on the length of the delay between application (evacuation) and the wildfire exposure.

If firefighters are at your home and know a gel-coating has been applied, they will mist the house with a water spray to rehydrate the gel.

A gel-product is being applied to one of the walls in this corner section. The siding is a nominal 4-inch wide end-and edge glued redwood siding having a rabbeted-bevel lap joint. The gel is being applied by the representative of the gel manufacturer. Half of the siding received the gel coating. A plastic sheet covered the other half during the gel application. For this demonstration, the gel was applied approximately two hours prior to the fire exposure.

A close up view of the coated wall.

Burning B brands [6-inches by 6-inches] were placed at the base of each wall section, as shown in these photographs. These burning brands provide a flame impingement exposure to the wall (i.e., with fire actually touching the walls). This kind of exposure would be the same as that from burning vegetation, fire wood, or other combustible debris located immediately adjacent to the building.

The heat output of a burning B brand is relatively small, as seen in this photograph. However, it would burn longer than a small to intermediate sized plant.

A view of the wall section early in the demonstration. The gel coated wall section is on the left.

Near the end of the demonstration the fire had burned up the uncoated wall, and was still burning. Flame did not travel far up the gel coated wall. Fire penetrated both the coated and uncoated siding in he vicinity of the B brand. In both cases fire was able to move into the stud cavity.

The results of this demonstration may have been different if the fire exposure had been purely radiant (i.e., vegetation or other burning materials located at a distance from the wall so that flames could not touch the siding).

This is a close up view of the over-lap / drip edge area at a lap joint, taken immediately after the gel had been applied. Note that drip edge doesnt have complete coverage. If a flame impingement exposure is possible, application of the gel to the under-lap area needs to be done completely.