How to reduce the vulnerability of decks

  • Create an ember-resistant zone under the footprint of and around all decks. This action will reduce the likelihood of under-deck flame exposure. 
  • If a deck overhangs a slope, create and maintain an effective defensible space downslope of the deck to reduce the chance of flames reaching the underside of the deck.
  • Apply metal flashing or foil-face bitumen tape on top of and a few inches down the side of the support joists. This is an effective strategy to minimize fire growth when a deck is ignited by embers, but would not help if the deck were ignited directly by flames under the deck. Using steel joists also reduces the vulnerability of the deck from both flames and embers.
  • For cedar and redwood decks, increase the size of the gap between deck boards to ¼ inch so that vegetative debris can fall through rather than accumulate on the deck. Be sure to routinely clear debris from under the deck. 
  • If a deck is made of combustible decking materials, replace the board closest to the home with a noncombustible material.
  • In new deck construction, consider using noncombustible or higher density decking products. 
  • Move combustible cushions from deck furniture to inside and relocate combustible furniture (especially those with woven components that can trap embers) away from the house.

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