Ember-Resistant Roof Details

Ember-resistant roof details are the small components of a roof that determine whether wind-blown embers (firebrands) can lodge, ignite debris or enter the attic during a wildfire. A building with a fire-rated roof covering can still ignite if embers reach combustible material through vents or gaps.

Where embers get in

• Attic and roof vents. Open vents draw air, and embers with it, into the attic.
• Gaps at eaves and ridges. The curved profile of barrel tile and some metal panels leaves openings at the eave and ridge that can collect embers and nesting material.
• Gutters and valleys. Accumulated leaves and needles ignite easily from embers and can then heat the roof edge and fascia.
• Open eaves. Exposed rafter tails and open soffits provide many ledges and gaps.
• Junctions. Where a roof meets a wall, dormer or chimney, debris collects and flashing gaps can admit embers.

Common measures

• Fine non-combustible mesh or ember-resistant vents. Wire mesh over eave, gable, attic and roof vents fine enough to stop embers; tested vent products are available in some markets.
• Bird stops and eave closures that fill the openings under the first course of tile or panels.
• Ridge closures that block the gap under ridge tiles or caps.
• Non-combustible gutters and gutter guards, plus regular cleaning.
• Enclosed soffits built with non-combustible or ignition-resistant materials.
• Clearing debris from the roof surface, valleys and around skylights and solar panels.

Vegetation and maintenance

Guidance for the wildland-urban interface recommends keeping plants more than 1.5 m (5 ft) from walls, pruning tree limbs about 3 m (10 ft) back from roofs, and clearing debris from roofs and gutters. IBHS research on the area within about 1.5 m of a home found vegetation there can increase exposure even when watered. Embers can travel more than 1.6 km (1 mile) ahead of a fire front, so homes well inside a neighbourhood are also at risk.

Codes

California's wildland-urban interface requirements, the International Wildland-Urban Interface Code, and Australia's AS 3959 all include provisions for vents, gaps and roof edges. In Australia the required detailing becomes stricter as the Bushfire Attack Level increases.