Phronesis-Online

Deck Fire Mitigation Brief (With Diagrams)

1. Deck-to-Wall Flashing

Purpose: Prevent flame or ember intrusion where the deck meets the house.

   Siding
     |
     |   <-- 2"+ vertical rise
  ____|________________
 |    |  Metal Flashing|
 |    |----------------|
 | Deck Ledger         |
 |_____________________|
        ^ 1" overhang

• Vertical rise: ≥ 2 inches
• Horizontal overhang: ≥ 1 inch
• Continuous flashing along all deck-to-wall contact points.

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2. Underside Protection

Purpose: Prevent embers from accumulating or igniting structural elements.

 Deck Joists
 -------------------------
 |                       |
 |   1/8" Metal Mesh     |
 | (Fully Enclosing)     |
 |_______________________|
     ^ Fine mesh blocks embers

• Required for decks <4 ft above grade.
• Use 1/8-inch metal mesh or non-combustible paneling.

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3. Railing/Stair Connections

Purpose: Remove direct fuel pathways into siding.

 House Siding
 |           |
 |  Flashing |<- Metal break
 |___________|
     ||
     || Railing/Step

• Maintain 1-inch separation OR install metal flashing between wood and wall.

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4. Fence-to-House Break

House ----[Metal Flashing]---- Fence

• Convert last 5–8 ft to metal or composite.
• OR insert metal flashing where fence meets siding.

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5. Ground Clearance

Siding
||  6" minimum clearance
||____________________ Soil

• Maintain ≥ 6” clearance between soil/duff and siding.

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6. Zero-Combustible Rule (0–5 ft Zone)

Everything burns except gravel and concrete. Keep:

• No lumber
• No plastic totes
• No stored gear
• No fuel cans
• No firewood

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7. Deck Surface Cleanliness

• Sweep needles/leaves weekly during fire season.
• Remove debris from gaps between deck boards.

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