Fire hazard – Gutters
The accumulation of debris in gutters poses one of the greatest fire hazards for a building. In the event that embers ignite debris, such as pine needles, the resulting fire will directly expose the edge of the roof to flames.
How can you protect your gutters?
The most important thing to do is to routinely clear debris from your gutters. Gutter covers can help preventing the accumulation of debris, but they may still require periodic attention. Using metal sheathing can be an effective way to prevent flames from reaching the attic in case of a fire, but not all the designs are effective. Examples of gutter covers and flashing techniques are discussed at the bottom of this page.
Chapter 7A of the California Building Code states that 'roof gutters shall be provided with the means to prevent the accumulation of leaves and debris.'' 'Prevent' will be hard to accomplish, but the intent is to minimize the accumulation of debris.
Chapter 7A of the California Building Code doesn't restrict gutter material, thus metal or vinyl would be allowed. Note that with metal gutters, in case of debris ignition the roof edge is the one exposed to flames. With a vinyl gutter, on the other hand, the gutter will likely detach and fall to the ground, exposing ground vegetation and potentially the siding.
Examples of gutters
|Metal vs vinyl gutter. This photo shows a metal gutter on the right. The gutter stays in place while the ignited debris burns, with the resulting flames impinging at the roof edge. A plastic gutter (shown on the left) eventually melts and falls to the ground. While the gutter is attached, flames are impinging on the edge of the roof as well. Once the gutter detaches, flaming debris and the burning gutter will re-locate to the ground. Plastic gutters will burn as long as combustible debris around it are burning. Regardless of the material of the gutter, it is extremely important to keep it clean from debris.|
|Over fascia-roof flashing. Metal angle flashing was used on the outside of the soffit assemble during a fire demonstration. Flashing wasn't included in the mid-section. Wood wool (excelsior) was used to simulate debris in the gutters as well as in the attic. A burning ember was simulated by a stick match. The fire ignited combustible material in the soffit. Flame penetration occurred in the mid-section where edge protection was missing. Angle flashing could have been more effective in blocking flame impingement.|
|Angle flashing. Pine needles accumulated in this gutter expose the roof edge to potential flames. The angle flashing used here will help protect the roof edge in case these pine needles ignite.|
|Integrated angle flashing. Gutter with an integrated angle flashing (the gutter and angle flashing are one piece). Similar to the separate angle flashing, this design provides much better protection as it covers both the fascia and roof sheathing.|
|Gutter and down spout covers. A variety of designs and materials can be found to prevent debris from accumulating in the gutters. If possible, avoid combustible materials that could burn during a fire.|
|Combination cover-screen. Section of a combination-type gutter cover, consisting of a solid metal cover (near the roof edge) and a screen (near the gutter lip). While this type of cover could improve the flame resistance of the roof edge, it could cause the accumulation of debris in the gutter-roof interface.|
|Gutter cover and debris. The screen stopped debris from accumulating in the gutter, but resulted in debris accumulating on the roof covering. Instead of routinely cleaning debris out of your gutter, you should now clean off your roof on a regular basis.|