One half of the house was built with cedar siding, vinyl gutters, single-pane windows, and bark mulch around the foundation. The other side had fiber cement siding, metal gutters, double-pane windows, and gravel around its foundation. Blowing embers that get a head start in combustible materials are the leading cause of wildfire ignition, IBHS researchers claim.
The IBHS recommends that eaves be closed and vents covered with ⅛-in. mesh rather than the ¼-in mesh often used. Deck joists should be topped with foil-faced bitumen tape wrapped partially down the sides under the planks, its research engineers opine.