4 Reasons to Rebuild with ICF Walls After Wildfire Devastation

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Rebuilding after a wildfire with Fox Blocks insulated concrete form (ICF) construction can protect a new structure and its occupants from future wildfires. Fox Blocks ICF have two- and four-hour fire ratings depending on the concrete core thickness, reported values for flame speed of below 25, and smoke development of below 450.

Wildfires can occur for many reasons ( e.g., human error or lightening); however, the results are almost always catastrophic. In 2017, there were 71,499 wildfires in the United States (U.S.) that burned 10,026,086 acres. The fires of 2017 destroyed a total of 12,306 structures; including more than 200 commercial buildings and more than 8,000 homes.

After a devastating wildfire sweeps through a community, it leaves many resistants and building owners with only a pile of ashes, memories, and questions about what to do next. For those that decide to rebuild a new home or building, effective wildfire protection is a top priority.

What to Consider when Rebuilding after a Wildfire

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The Federal Emergency Management Agency (FEMA), the Firewise Communities, the Federal Alliance for Safe Housing, and the Institute for Business and Home Safety work together to provide a resource for rebuilding after a fire to ensure a new home or building is safer, smarter, stronger, and more resilient to wildfires. It is essential, before rebuilding after a wildfire, to understand what starts and spreads a wildfire and what makes a structure prone to catching fire.

What a Wildfire Needs to Start and Spread

  • Fuel, weather, and topography determine how quickly a wildfire spreads and at what intensity.
  • Vegetation, particular the crowns of trees, quickly and intensely spreads wildfire.
  • Flames can soon spread between close neighboring structures.
  • High temperatures, low humidity, strong winds, along with short- and long-term droughts, heighten the chance of ignitions and increase the difficulty of controlling the wildfire.
  • Fires that spread along a 30 percent slope can move a grass fire up to four times faster than a smaller slope.

Ways a Home or Building Catches Fire

Wildfire attacks a building through either radiate heat, convection, or firebrands. The building’s or home’s materials and design play a critical role in determining the level of exposure a structure can endure before becoming ignited either by radiation, convection, or firebrands.

  • Radiant heat (thermal radiation) is a heat transfer that does not require a medium to spread. Radiated heat takes the form of light rays, which are capable of igniting combustible materials from 100 feet or more.
  • Convection is a heat transfer when hot air rises away from the heat source. Convection causes a fire to spread into treetops, up hills, into treetops, and towards the ceiling.
  • Firebrands are little fiery bits of burning embers that shoot off from the main fire. Firebrands can travel by fire-generated winds of distances of more than a mile.

Rebuilding with ICF Walls after Wildfire Devastation

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Rebuilding after a wildfire with insulated concrete forms (ICFs) is a best practice for protecting a home or building from the next wildfire. The first line of defense against a wildfire is to surround a structure with an area of reduced fuels, which can help slow an approaching wildfire.

The second line of defense against a wildfire is a structure’s exterior walls. The exterior wall stops flames from burning the interior walls, attic areas, glazings, soffits, and rooms. The exterior material must also not lose its integrity when exposed to high temperatures. An ideal protect for rebuilding after a wildfire is ICF.

Four Reason Why Building with ICF Walls Protects Against Wildfire

  1. ICF walls do not warp, twist or burn under high temperatures. Firewall tests (ASTM E119), found that ICF walls hold up to continuous gas flames and temperatures of up to 1093°C (2000°F) for as long as 4 hours. Wood-frame walls break down in less than one hour.
  2. According to flame spread test (ASTM Test Method E-84) conducted by the PCA, ICF flames move at only one-fifth the rate as flames from wood.
  3. The flame retardant added to most ICF products makes it self-extinguishing; therefore, ICF does not contribute fuel to the fire.
  4. ICF interior walls act as separation walls that slow the fire from spreading within the interior of a structure. ICF walls can resist intense heat for four hours , while wood frame walls may collapse in an hour or less of flame exposure.
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The photo was taken in 2007 after a wildfire destroyed a San Diego suburb. Only the ICF homes on the street survived the fire. https://www.icfmag.com/2008/08/fireproof-icfs/

Other Important Factors for Rebuilding After a Wildfire Devastation

Along with wall construction, there are several other crucial design characteristics of a fire-resistant structure.

  • A fire-resistant design must include Class-A asphalt shingles (slate or clay tile, metal or cement, and concrete products), along with a fire-resistant sub-roof.
  • Fire-resistant glazings, with double pane and tempered glass.
  • Cover vents so to prevent sparks from entering the building.
  • Remove fire fuel from yards, gutters, etc.

Increasing Numbers of Wildfires Demands Fire-Resistant Construction

With the rise in wildfires and longer wildfire seasons, those looking to rebuild after a wildfire must consider fire-resistant design. A vital component of fire-resistant design is a wall system that limits the spread of flames and smoke from the exterior and within the interior of a home.

An excellent wall system for rebuilding after a wildfire is Fox Blocks ICF. The 6-inch Fox Blocks have an ASTM E119 fire rating of four hours (twice the two-hour requirement), an ASTM E84 reported values for flame speed of below 25 and smoke development of below 450. Other fire-resistant features for rebuilding after a wildfire include fire-resistant roofs, glazings, and vents. In additions, the surrounding area must be free of fire fuel.