If you own a cabin or live in the woods, experts on keeping property safe from wildfires say there’s one big thing you can do to increase your odds that the building will stand.
Have a big yard with short grass and few trees.
Of course, some fires move so fast and burn so hot that they consume everything in their path. But a comprehensive study after a devastating 2013 wildfire south of Solon Springs in Douglas County, Wisconsin, found that the amount of cleared, open space between the building and the forest was the key factor in whether the home or cabin burned down or survived.
The width of the driveway was the second-biggest factor.
While experts have been touting the Firewise program of open space around rural properties for years — with 30 feet of cleared area considered a minimum — the study by the Wisconsin Department of Natural Resources really hit close to home. DNR crews conducted the post-fire assessment just six days after the May 14, 2013, Germann Road Fire spread across 7,442 acres, destroying 23 homes and cabins and another 81 structures in just a few hours. It was Wisconsin's largest wildfire in 33 years.
To the untrained eye, the pattern of destruction might appear random. But fire officials say that clearly was not the case. Home and cabin owners who had cleared ample space around their buildings, and who had a wide access onto their property, stood the best chance of seeing their homes or cabins survive.
The DNR study looked closely at 96 of the 100 homes and cabins that were in the path of the fire. The average structure that survived the flames was 27 feet away from “unmanaged” heavy vegetation in the woods, the report concluded. Buildings destroyed were an average of 19 feet from the woods.
Even if trees don’t touch or overhang, a torching pine 15 or 20 feet away can burn so hot that the siding of nearby cabins simply combusts.
“And don’t forget about the firewood pile. If that's stacked against the house and an ember falls on it, it’s going to ignite your house. … Get that firewood pile out 30 feet or more,” said Allissa Reynolds, acting wildfire prevention supervisor for the Minnesota DNR. “Many times, when our firefighters arrive at a structure, if they have time, the first thing they do is start moving firewood piles. But it’s a lot better if you’ve already done it.”
Reynolds said that a series of mostly wetter summers may have given some Minnesotans a false sense that wildfires don't burn cabins here as they do in California, and so some cabin owners choose woodsy ambiance over cleared-yard safety. But this year's Greenwood Fire near Isabella, which has destroyed at least a dozen buildings, is a stark reminder that it can happen here.
In the Wisconsin study, nearly as important as open space was how far homes and cabins were from other “outbuildings.” While the home itself might be 30 feet from thick vegetation, sheds, garages and even outhouses closer to the woods often ignited, carrying the fire to the house itself.
In one case, the study team followed the ash pattern across a yard. The fire had mostly stopped at the outside yard edge, but the shed was right up against the trees, so it burned. Then the shed fire caught the garage on fire. Then the fire jumped from the garage to the house and the house was destroyed.
- Creating 'defensible space' can be key to homes surviving wildfires
- Sprinkler systems prove their worth
The lesson was that you need 30 feet of cleared space around sheds and other outbuildings, too. The fire analysis showed the average distance between forest and outbuildings that burned was just 6 feet. Outbuildings that survived averaged 17 feet from heavy foliage.
“That building-to-building distance is just as important, because a burning building carries so much heat and flame, longer than a burning tree. People don't think about it, but you need that 30 feet around your shed, too,” Jolene Ackerman, wildland-urban interface coordinator for the Wisconsin DNR, said when the report was released.
Wide driveways key
The Germann Road Fire also showed that it's critical that driveways be wide enough for large fire trucks to drive down and turn around as crews make hurried “triage” decisions during fires on which properties are defendable and which are unsafe for them to enter. Even a wide driveway can be a problem, however, if trees overhang — fire trucks can be 10, even 12 feet tall.
Not a single home or cabin was lost to the Germann Road Fire where the driveway clearance was 20 feet or wider. Thirteen properties had driveways narrower than the recommended minimum of 12 feet, and six of those were destroyed.
“The crews need to be able to get in and get out fast. You don't need 20 feet of concrete or blacktop. But it has to be wide enough between the trees and stumps for them to pass,” Ackerman said.
Reynolds said another good addition is a wide turnaround space at the end of the driveway, right at the cabin. Firefighters need to be able to get their trucks in and out quickly.
“You don't need a moonscape to protect your home,” Reynolds said. "But keeping it mostly open can make all the difference.”
The Wisconsin study found properties with gates were slightly more likely to have burned, 33%, than those without gates at 22%. But other variables had surprisingly little bearing on fire survivability, including how long the driveway was or how big or expensive the home was. The assessed value of primary buildings destroyed ranged from $3,500 for a seasonal mobile home to $313,000 for a year-round home.
And the report shows that it's important to take action before a fire and not to depend on firefighters to save your home. Of the 100 properties in the fire's path, crews were on hand for 38 of them at some point during the fire — including pretreating homes and buildings with fire-retardant foam, actively dousing flames, clearing flammable debris (like woodpiles) or rapidly digging fire breaks with bulldozers.
Firefighters likely saved as many as 23 homes and cabins by their actions, the report found. But seven cabins or homes burned even with crews on the scene trying to save them.
Hot, dry, windy day
The 2013 fire started off Germann Road, just east of U.S. Highway 53 near Gordon, in hot, dry conditions in a place — a jack pine, red pine and scrub oak forest with sandy soil — that's subject to frequent wildfires. All it took was a spark, and that came from a piece of logging equipment, to start a major fire pushed by the wind. The fire burned across 12 miles in a few hours in the towns of Gordon and Highland in Douglas County and then spread into the town of Barnes in Bayfield County.
The fire burned in a mosaic pattern of damage along 8 miles. As with most wildfires, not everything in the fire's path was destroyed. Some areas were hardly burned while others were charred, leaving miles of blackened trees and ground. The fire burned so hot that aluminum siding on homes melted. A swing set was melted and deformed in the yard of a house that had burned to ashes. Power poles burned, downing lines. Even wooden guard rails along roadways were burning.
Metal roofs, sprinklers and more
There are many steps property owners can take to guard against wildfires, from installing a metal or other fire resistant roofing, to prevent embers from torching the building, to installing lake-pump sprinkler systems that cover the buildings in a cool, protective blanket of wet as the fire approaches. Those sprinklers, powered by gas or propane powered motors for when electric lines fail, were credited with saving dozens of homes and cabins along the Gunflint Trail during the 2007 Ham Lake fire.
In some cases community grants are available through DNR forestry programs to pay for Firewise efforts, such as brush removal and driveway hardening and widening, Reynolds noted. Contact your regional DNR forestry office.
For more information on protecting rural homes and cabins from wildfires, go to the National Fire Protection Association website at nfpa.org, the Minnesota DNR Firewise site at dnr.state.mn.us/firewise or Wisconsin DNR at dnr.wisconsin.gov/topic/forestfire/preparing.
The Minnesota DNR also has a list of 50 things you can do to help protect your home against wildfire at dnr.state.mn.us/firewise/50things.html.