Rain Gutters
When ignited by embers, the burning debris in the gutter will provide a flame contact exposure to the edge of the roof. The protection provided by the roof edge must be sufficient to resist the entry of flames into the attic space or cathedral ceiling. The roof edge must also protect against the ignition of the exposed roof sheathing or the exposed fascia board. The exposure is more severe if metal angle flashing is not used at the roof edge and if the gutter is hung below the roof edge, leaving the roof sheathing exposed.
The most important thing you can do for the gutter is to keep it clear of debris. This debris can be readily ignited by embers during a wildfire. The material that the gutter is made from is less important. A metal (noncombustible) gutter will stay in place while the debris burns and the resulting flames will impinge on the edge of your roof (not your Class A roof covering, but the edge of it).
The vulnerability of the roof edge will depend on materials used and how well the flashing if used, protects the edge. On the other hand, a vinyl (plastic) gutter will quickly melt, detach, and fall to the ground (Jennings 2000). The burning debris will fall with it and continue to burn on the ground. Once on the ground, the roof edge is no longer exposed to flames, but combustible siding may be, particularly if the near-home vegetation or ground cover can easily ignite. The problem with gutters is that the debris can accumulate in them. Keep debris outof them, and the problem goes away. Inspection and removal of debris in gutters should be done before fire season and as necessary thereafter. Since debris, just like burning embers, can be blown in from surrounding areas, a good vegetation management ( fuel reduction) plan around your property can reduce, though not eliminate, the accumulation of debris in gutters. A pre-evacuation task that would alleviate the problem of some debris accumulation in a gutter would be to plug the downspouts and fill the gutter with water. The downspouts would be uncovered upon returning home.
Given the potential problems with gutters, why not just do away with them? Properly installed and maintained gutters and downspouts play an important moisture-management role for a building by collecting and moving waterto where it will not have a negative (moisture- related) impact on the foundation and crawl space. (A properly installed subsurface drainage system, however, could alleviate the need for gutters.)
A number of gutter cover devices are commercially available. These products are intended to limit the accumulation of debris in the gutter and allow for the free flow of water into and out of them. These devices either cover the gutter witha solid material or screen or fill the gutter with a porous (foam) material. There is variability in the cover devices, including those that 1) incorporate a screen that completely covers the gutter,2) incorporate a solid, thin metal sheet that coversthe gutter but has an opening at the outside edge to allow water to enter, or 3) use a hybrid metal cover/louvered design. The solid, thin metal cover relies on the surface tension of water, releasing from the rounded metal edge of the cover to drop into the gutter. The porous foam devices allow water to enter and flow through the gutter while excluding debris larger than the pores. A procedure to evaluate the performance of these devices has not been developed, so if you are consider- ing one of them, review the available literature that represents a range of designs and look at devices installed on nearby homes. The devices require maintenance–with some thereis a tendency for debris to accumulate on the roof behind the device, which you should remove. None of the available devices is likely to be completely maintenance-free.
