Recommended Materials

• Concrete
• Fiber-cement panels
• Pressure impregnated fire-retardant treated wood and panels
• Traditional three-coat stucco
• Masonry
• Metals (steel)

NOT Recommended

• Non pressure impregnated fire-retardant treated wood siding or panels
• Vinyl siding (will deform and fall off the wall at relatively low radiant heat or flame exposures)
• Metal siding susceptible to warping (aluminum)
• Exterior insulation finish systems (EIFS)

If you have a combustible siding and are unable to replace it in totality, target smaller areas that are vulnerable such as the 6-inch at the base of the siding and the roof-to-wall area. Creating a 6-inch noncombustible area at the base of the siding will minimize the chance that the siding will ignite from embers at the ground level or direct flame contact.

About Fire-retardant Coatings

Intumescent coatings, often referred to as intumescent paint, are used in buildings as a passive fire resistance measure. Usually, they have been developed for interior use are sometimes suggested for use in exterior applications, either applied as a primer or topcoat, on products such as siding.

While these products may work well in interior applications, they tend to lose effectiveness when used in exterior locations. The use of coatings as fire retardants should be avoided in exterior exposures until adequate information regarding performance after weathering has been demonstrated.

Exterior Doors

1. Install a fire-rated door and frame. Doors with a solid, noncombustible mineral core are classified as fire-rated doors. Exterior fire-rated doors are available with a rating of 1½ hour or 3/4 hour.
2. For door glass vision panels and glass sliding doors, follow recommendations in Windows & Skylights.

Weatherstripping

Install adjustable weatherstripping on the interior side of the door frame and specify and install an automatic door bottom or threshold weatherstripping. The weatherstripping and door bottom should be tested in accordance with UL Standard 10C. Weatherstripping is relatively inexpensive.

Garage Doors

1. Install insulated, metal garage doors.
2. Install weatherstripping that has been tested in accordance with UL Standard 10C around the entire garage door.

For exterior trim that covers the opening between the door frame and exterior wall. Install noncombustible or fire-resistant material such as fire-retardant-treated wood or fiber-cement board.

Fire resistance of common materials used for landscape fencing

Wood
Fences that are constructed of wood or have wooden components are combustible and therefore provide no fire resistance. A wood frame with steel mesh infill is an option that would minimize the possibility for an ember ignition; however, if vegetation is allowed to grow on the mesh infill, this advantage will be negated.

Plastic
Plastic fences are more fire-resistant, more durable, and often stronger than wooden fences, but plastic fences can melt in a wildfire from temperatures that are below the maximum a wildfire can generate.

Metal
Metal fences are more fire-resistant than plastic fences. Wire fences such as barbed wire, hog wire, and chain link have little or no effect on fire passage. However, if combustible materials have accumulated in or around the fence, it can act as a horizontal ladder fuel by allowing the fire to travel along the fence.

Concrete, stone, or masonry
Concrete, stone, and masonry fences and walls are noncombustible and can act as a barrier to a wildfire by deflecting flames away from a building.

Key Considerations for Increased Fire Safety

• Avoid attaching fences and walls constructed of combustible materials to a building.
• For fences and walls that are attached to a building, ensure that all combustible components are at least 5 feet from the building to prevent heat and flames from igniting the building. A common technique is to use a metal gate with one side attached to the combustible fence and the other to the building.
• A fence design that allows for greater air flow, such as a single panel lattice fence, makes it more difficult for wind-blown embers to accumulate at the horizontal to vertical intersection. For this reason, privacy fences with all planks on one side are the most vulnerable to ignition.
• A fence with lattice applied to both sides of the support posts should be avoided due to fire growth and lateral flame spread.
• Avoid combustible mulch and vegetation within at least 2’ of combustible fencing.

Plastic and Wood-plastic are also Combustible

It is common knowledge that wood deck boards are combustible. There is sometimes a misunderstanding regarding the combustibility of plastic and wood-plastic composite decking products—these decking products are also combustible.

Recommended Spacing

Untreated wood and wood treated with fire-retardant, as well as plastic and wood-plastic composite products are all combustible and therefore vulnerable to ember and other wildfire exposures. However, the deck can be designed to minimize exposure to embers:

• Increase the gap between deck boards from 1/8 inch to 1/4 inch.
• Increase joist spacing from 16 inches to 24 inches. Apply a foil-faced self-adhering adhesive flashing tape (foil-faced bitumen tape) on the top of each joist. Foil tape should extend down each side of the joist 2-3 inches.