Posted on: May 19, 2017

Ember Aware Campaign: Tip #5 - Vulnerable Vent Dilemma

Be Ember Aware!

WILL YOUR HOME SURVIVE WHEN THE EMBERS ARRIVE? Wind driven embers ignite many of the homes destroyed by wildfire. Your home could be at risk! BE EMBER AWARE and make changes to reduce the threat to your home. Remove leaves and pine needles from your rain gutters, chuck that firewood, and clean out debris from under your deck. You can learn more at www.emberaware.com. Most people believe that wildfires ignite homes through direct contact with flames, but it is rare to have a home ignite this way. Flaming brands and embers can travel a mile or more ahead of the active front of a wildfire and up to 60% of wildland/urban interface home ignitions result from embers.

Tip #5: Vulnerable vent dilemma.

Vents play a critical role in your home by allowing excess moisture to escape from the attic and crawl space. If moisture was allowed to accumulate in these areas, your home could be threatened by mold and decay fungi.

During a wildfire, vent openings have also been shown to be one vulnerable spots for ember entry into your home. This creates a dilemma for homeowners. Many vents use wire mesh coverings with a ¼ inch screen. Smaller mesh sizes can become clogged by paint, cobwebs, debris, etc. that reduce air flow. Unfortunately, the ¼ inch mesh is not effective in preventing ember entry into the attic, eave, and crawl space vents. For existing homes, consider the following:


·        Replace 1/4-inch mesh with 1/8-inch mesh, if required air flow allows. Be sure to keep the mesh openings unclogged.

·        Use metal wire mesh, not plastic or fiberglass.

·        Don’t store combustible materials, such as paper, clothing, etc. in the attic or crawl space.

·        Clear fallen pine needles, leaves, dried grass and other debris from around vents (a particular problem with through-roof vents, such as a dormer or ridge vent).

·        Do not plant shrubs in front of or underneath vent openings.

·        Create pre-made covers out of plywood to install over vent openings if wildfire is approaching and there is time. In an emergency, it may help to fold several layers of aluminum foil and staple over vent openings.


New ember resistant vent designs are available. Check with your fire marshal or building official for advice on these and other measures to reduce the potential of embers entering your home.  


Author bio:

Dwight Good, Fire Marshal, MS, EFO. Serving the Morgan Hill Fire Department, South Santa Clara County Fire Protection District, CAL FIRE Santa Clara Unit. 24 years of fire service experience.

Questions and comments to: Dwight.good@fire.ca.gov or (408) 310-4654

Decks can contribute to the wildfire threat to your home. Take steps now to reduce the deck danger. 

Questions and Comments: Dwight.good@fire.ca.gov or 408.310.4654

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