Wildfire experts have seen a common pattern around the country in how wildfire destroys homes: Typically, windblown embers—which can fly for a mile or more in a high wind—are the biggest danger to homes. Sometimes the embers land on a roof or collect in a gutter or valley, setting fire to accumulated leaves or pine needles. Sometimes they pile up at the base of a house wall, then ignite siding or the exposed bottom edge of sheathing. Sometimes, heat from burning trees or neighboring houses shatters windows, and embers blow into the house and set furniture or curtains on fire. And very typically, embers get sucked into soffit or gable-end roof vents, igniting the attic and burning the home from the top down.

In a big wildfire, strong winds may carry hot embers or even large flaming firebrands for long distances. Embers can be sucked into soffit vents or land in gutters, where accumulated pine needles or leaves may catch fire. The detail above reduces these risks; the soffit and fascia are noncombustible fiber cement, the roof is concrete tile, and metal flashing laps down into the metal gutter. The rough bottom surface of the tile allows moisture to weep out, but restricts the entry of flame and embers.
In a big wildfire, strong winds may carry hot embers or even large flaming firebrands for long distances. Embers can be sucked into soffit vents or land in gutters, where accumulated pine needles or leaves may catch fire. The detail above reduces these risks; the soffit and fascia are noncombustible fiber cement, the roof is concrete tile, and metal flashing laps down into the metal gutter. The rough bottom surface of the tile allows moisture to weep out, but restricts the entry of flame and embers.

To learn more about building to reduce wildfire risk, consult the following resources:Living with Wildfire (JLC)
A Passive House in Wildfire Country (JLC)
Preparing Homes for Wildfire (NFPA)