Fence vulnerabilities

Fencing can increase or decrease a building's vulnerability to wildfires depending on its material and location. Combustible fences may ignite from direct flame contact or from embers depending on their state and the nearby vegetation. If the fence is attached to the building, it could create a path for a fire to reach exterior walls and eaves. Solid perimeter fences made of noncombustible materials (such as steel or concrete) are effective barriers against radiant energy exposure from fire fronts. Even a wood plank fence, if a high-density species is selected and the boards are closely spaced, can provide some protection to the building from a purely radiant exposure. Vinyl fences would likely melt during fire conditions.

Examples of fences

	Wooden fence. It is helpful for the fence to have the grass trimmed, but it is exposed to larger vegetation. There is no protection from radiant heat or embers from this fence. Keeping grass and vegetation low near the fence could prevent ignition.
	Fence attached to a building. This fence consists of small structural components (which are easier to ignite) and is connected to an exterior wall (which creates a direct path for the fire). A noncombustible section should be added close to the exterior wall.
	Wooden frame with metal wire. It provides good protection from flame spread along the fence. It does not, however, protect against embers or radiant heat.
	Combustible fence with metal gate. The fence has a metal gate (safe choice) and could block radiant heat. If ignited, however, the house could be exposed to radiant heat. Vegetation close to the fence should be removed.
	Wooden lattice fence. During a fire demonstration, a wood lattice fence was ignited with a burning standard 'B' brand. The fire was not sustained and did not spread to the wall, even though fine combustible debris was stuffed into areas in the lattice fence. The fire likely didn't spread to the wall because of the lack of pre-wildfire exposure prior to the demonstration (high temperatures, high winds, low relative humidity, and pre-radiation exposure over many days). In a fire demonstration, exposing materials to actual wildfire weather is difficult.
	Vinyl lattice fence. During a fire demonstration, a vinyl lattice fence was ignited with a burning standard 'A' brand. The fire did not spread to the wall, even though fine combustible debris was stuffed into areas in the lattice fence. After the 'A' brand burned out, the vinyl lattice deformed, but did not sustain combustion. During a fire demonstration, however, it is difficult to replicate wildfire weather conditions.

How can you protect your fence?

These are some general guidelines to reduce the risk of ignition of fences:

• If your fence is attached to your house, replace the last 5 feet with a non-combustible section (a metal gate for example) to break the potential fire path
• Consider replacing the fence using fire-resistant materials
• Remove vegetation (grass, shrubs, lower tree branches) and combustible materials in contact with the fence

California regulations

Fences are not included in Chapter 7A.