University of California
Homeowner's Wildfire Mitigation Guide
Edge of Roof Issues
Even a Class A roof can be vulnerable at its edges. You can argue that the roof edge is no longer the roof, but regardless, it is still important to understand, and address, these vulnerabilities. Debris often accumulates in locations where the roof changes slope (for example, where the roof intersects with a wall and in the valley). During wildfires, embers will also collect at these locations, igniting the accumulated vegetative fine fuels (pine needles, leaves, etc.). If the material that your Class A roof intersects with doesn’t provide the same or similar protection, then your roof is vulnerable. For this reason, it is important to be vigilant about removing debris from your roof.
If ignited, the debris on this roof would expose the underside of the overhanging roof, or the exterior siding. Both of these components are potentially more vulnerable to flame and ember exposure than a Class A asphalt composition shingle roof covering.