Wildland-Urban Interface Demonstration Building - Eaves & Soffits

This photograph is of the opposite side of the demonstration building, and was taken on a rainy day. Note that the overhang on this side of the building protects the upper half of the window from rain exposure. Water leaks on the exterior wall of a building most often occurs at penetrations, such as at a window.

A fiber cement material was used to "box in" the soffit in the foreground, and plywood was used to box in the soffit in the background (the 1" thick board separates the two materials). The fiber cement soffit is a noncombustible material, so is able to resist flaming and ember exposures. A thicker (3/4"), higher grade plywood (fewer knots in outside and internal veneers, and minimal core gaps [gaps between internal veneers]) will improve performance. A vinyl soffit strip vent with 1/8" holes was used with the fiber cement soffit, and a metal louvered strip vent was used with the plywood soffit. Both of these vents would be vulnerable to a flame exposure, and embers entering either of these could still have sufficient energy to ignite fine fuels that can be found in attics. Vents located closer to the roof edge will be less vulnerable to flame and ember exposures. As was the case with frieze-block and gable end locations, vents that resist ember and flame exposures are commercially available, at least in California.