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Be Ember Aware Tip #5: Vents make you vulnerable

Posted 5/26/2009

Note: This is the fifth in an ongoing series of tips for homeowners living in fire-prone areas. Each week, Cooperative Extension Natural Resource Specialist Ed Smith will be providing Be Ember Aware tips for homeowners who want to reduce the risk of losing their home to embers created from wildfires. Nevada has more than 250 communities that face a wildfire threat, and 68 communities are at extreme and high risk. For more information on protecting your home from wildfires, visit Living With Fire.

By: Ed Smith, natural resource specialist, University of Nevada Cooperative Extension

Vents play a critical role in the long-term preservation of your home by allowing moisture to escape from the attic and crawl space (if present). If moisture were allowed to accumulate in these areas, the wooden features of your home could be threatened by mold and decay.

During a wildfire, vent openings have also proven to be one of the most vulnerable spots for ember entry into your home. The Wildfire Lessons Learned Center’s "Southern California Firestorm 2003" report concluded after reviewing the loss of 3,340 homes destroyed by wildfire that ornamental vegetation created an unpredictable and significant fuel source that blew into attic vents and eaves and spread through neighborhoods by torching, crowning, or throwing embers. Structures became involved from ember attack from the inside out rather than flame impingement.

This creates a dilemma for homeowners. Many vents use wire mesh coverings. Some building codes set the minimum mesh size for these at one-quarter inch. Smaller mesh sizes can become clogged by paint, cobwebs, debris, etc. and may reduce air flow. Unfortunately, the one-quarter-inch mesh has not been totally effective in preventing ember entry into the attic, eaves, and crawl space. For existing homes, consider the following:

  • Replace one-quarter-inch mesh with one-eighth-inch mesh, if building codes and required air flow allow. Be sure to keep the mesh openings unclogged.
  • Use 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.
  • 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 situation, it may help to fold several layers of aluminum foil and staple over vent openings.

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

To learn more about protecting your home from the ember threat, visit Living With Fire and request a free copy of our new publication, Be Ember Aware! You can also download it at University of Nevada Cooperative Extension or contact Ed Smith. Be Ember Aware is a component of the Living With Fire program, an interagency program coordinated by University of Nevada Cooperative Extension.

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