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Fire Spread Pathways

There are dozens of pathways for fire to spread through communities. Even just one vulnerability can ignite a structure, potentially leading to the ignition of numerous additional structures and the loss of an entire community. Pathways often differ depending on the type of exposure, therefore, a home must be protected from both embers and fire.

The animation below shows an example fire spread pathway between neighboring parcels. Note that while Residence B is protected by a safe Structure Separation Distance, SSD, between the structure and gazebo, and installation of a non-combustible fence, the fire can still spread to the neighboring structure.

  1. Embers ignite gazebo located away from Residence B
  2. Fire spreads from the gazebo and ignites wood fence
  3. Fire spreads along a wood fence and ignites an RV parked on the property
  4. RV fire ignites wood deck
  5. Wood deck fire ignites home
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Parcel-level combustible components (primary or neighboring parcels)

Detached combustibles
  • Fences
  • Firewood piles
  • Railroad ties
  • Mulch
  • Ornamental vegetation
Attached combustibles
  • Decks
  • Pergolas
  • Awnings
  • Cars
  • RV’s
  • Boats
Secondary Structures
  • Sheds
  • Barns
  • Car ports
  • Auxiliary dwelling units (ADUs)
    ("In-Law Suite")


Additional examples of fire spread pathways

* Numerous fire spread pathways among neighboring properties via linear features and other combustibles from a single ignition point (B).

* Fire can spread along combustibles like fences and shrubs (A)

* Fire can spread along fences and ignite sheds which can ignite home (B)

* Fire can spread along parallel fence and mulch beds and ignite homes shrubs, and sheds which can spread fire to homes across properties.
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Created July 6, 2023, Updated August 8, 2023