Wildland-Urban Interface Demonstration Building - Vents

Wildland-Urban Interface Demonstration Building
Roofing & Gutters Vents Eaves & Soffits Windows Siding Near-home

The frieze-block (circular) vents are commonly used in the open-eave construction shown here. Vents in the eave are vulnerable to the entry of embers (from the wildfire and / or burning landscaping vegetation), and flame (from near-home vegetation, or upward flame spread from combustible siding). Studies have shown that the 1/4" or 1/8" mesh screens typically used with these vents will still allow the passage of embers large enough to result in the ignition of fine fuels in the attic. These vents used 1/8" mesh screens. Vents designed to resist ember and flame intrusion have been developed, and are available in some locations.


In addition to the frieze-block openings, between-joist blocking in open-frame eave construction can be vulnerable to ember entry and exposure if it isn't tightly installed against the wall (below), joists (both sides), and roof sheathing (above). In this photograph there is a clear opening at the bottom of the blocking where embers could easily enter.