On May 5, 2007, an unattended campfire in Minnesota’s Superior National Forest ignited the massive Ham Lake Fire. At the time, it was the second largest wildfire in the state’s history.
A dry winter and spring, coupled with strong winds, fueled the destruction of 75,000 acres and hundreds of properties.
But 188 Cook County homes and resorts were not among the casualties. Six years earlier, these properties had been retrofitted with exterior fire sprinklers.
According to the California Chaparral Institute, all 188 structures were spared — even though more than 100 of the neighboring properties didn’t make it — because of the exterior sprinklers.
A year after the Ham Lake Fire, a research team from the University of Minnesota concluded that “[N]o structure with a functional sprinkler system was lost to the Ham Lake Fire. This was true regardless of fire behavior, intensity, surrounding fuels, or wind.” [Emphasis added.]
Exterior sprinklers work by creating an environment that extinguishes embers — the primary cause of home ignition. The sprinklers do this in three ways:
Prior to the Ham Lake Fire, it was believed that exterior sprinklers had to run many hours in order to fully hydrate potential fuels. But apparently not.
The crews who battled the Ham Lake Fire reported that some sprinkler systems had run for as little as two hours before the wildfire arrived. The cooler, moister environment created by the sprinklers suppressed the embers before they were able to ignite the fuels, whether structures or vegetation.
While extreme, wind-driven wildfires may be inevitable, wildfire disasters are not.
As renowned fire scientist Jack Cohen has repeatedly stated, the wildland fire problem is a home ignition problem, not a wildfire control problem. In the following video clip, Cohen explains how homes ignite during wildfires, and the preventive actions homeowners can take:
For years municipal fire departments have worked to improve building codes to include more fire-resistant materials. And they’ve recently also promoted the concept of defensible space. However, last year’s deadly California wildfires indicate these measures may not be enough.
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Did you know that the Class A firefighting foam used in the Frontline Wildfire Defense System actually makes water “wetter”?
The foam attracts carbon and soaks into solid, combustible materials by breaking down the surface tension of the water. It helps the water penetrate the burning material to quickly suppress the fire and prevent rekindling.
In fact, the National Institute of Standards and Technology has estimated that water treated with Class A foam can wet a Class A fuel up to 20 times more rapidly than untreated water.
FEMA agrees that “Class A foam products, and other long-term fire retardants … provide greater thermal protection than water alone.” Which is why most municipal fire departments rarely use anything else.
In addition to the Ham Lake results, there are plenty of success stories where am exterior sprinkler system has protected a house from burning. You can read about two such examples of eave sprays and roof sprinkler systems that saved homes in the 2003 Cedar Fire in San Diego and the 2018 Camp Fire in Paradise. And Frontline’s customer in Wyoming saved her home in the 2018 Roosevelt Fire.
That said, when evaluating wildfire defense systems, there are a few critical capabilities. First, remote, satellite-enabled activation is key, so you can operate your system after you’ve evacuated or while travelling. Second, backup water and electricity sources are a must. And third, using an effective Class A firefighting foam, as described above, will amplify the protective wetting qualities of water.
For more on this, see our post “Three Key Questions and Capabilities for Effective Wildfire Defense Systems.”