How likely is a home to burn in wildfire? New scale rates the risk

Below are excerpts from Rob Chaney’s article in today’s Missoulian:

It’s common to assume the walls of flame under a towering smoke column pose the biggest threat in a wildfire, said Jack Cohen, a scientist at the Rocky Mountain Research Station in Missoula. That’s true for people, but not for houses.

“The same heat radiation that on my exposed skin will give me a second-degree burn in 5 seconds, takes 27 minutes to ignite wood,” Cohen said. “Firefighters are way more vulnerable to big flames than a house is. That tends to skew what we pay attention to.”

In most of the lost-house incidents he has studied, Cohen found the residential destruction took place eight to 10 hours after the big flame front moved through. That’s when embers finally ignited piles of pine needles in a rain gutter, or leftover lumber under a deck, and eventually burned the house down.

“Unless houses are mitigated to be ignition-resistant, firefighters can’t be effective in well-developed residential areas,” Cohen said. “There aren’t enough firefighters and resources to assist and suppress ignitions on all houses exposed.”

Several new tools have appeared in the past year that may make the homes lost in Lolo Creek less common. A fire hazard scale developed by the National Institute of Standards and Technology and U.S. Forest Service can suggest changes in building codes similar to how the Richter Scale defines risk in an earthquake region.

Last month, a task force gathered by Colorado Gov. John Hickenlooper proposed a way to rank homes based on fire risk. [Note: We discussed the findings of the task force on the blog here.]  Montana Building Association government affairs specialist Dustin Stewart attended the conference where it was unveiled.

“Every home would be given a grade on a sliding scale from 1 to 10 to determine its susceptibility to wildland fire,” Stewart said. “It’s not entirely clear who would use the grade. Insurance companies could potentially use it when developing policies for wildfire. Or it could trigger a mandatory fire mitigation for those homes with high grades.”

Stewart said the Colorado Homebuilders Association members he talked with were not in favor of the plan, warning it could “hang a scarlet letter on the house.”

“It could severely impact resale value,” he said. “And it becomes very politically unpopular when you tell 10,000 residents across the state they have to disclose this number when they sell their house.”….

“The ignition zone is usually on private property, and that changes the social dynamics,” Cohen said. “We don’t have the authority to go in and tell people to make changes or to make changes ourselves. We have to have homeowner agreement, engagement and participation in reducing their vulnerability.”

In other words, labeling people from space won’t save any houses next summer. Stewart, at the Montana Homebuilders Association, had a similar observation.

“I think incidents like Hurricane Sandy, the Oklahoma tornadoes, the wildfires in Colorado – they’re going to become a bigger part of the public discussion in new construction standards,” Stewart said. “But there are things people can do without creating another level of government. That’s a nice thing about living in Montana. We don’t need to reinvent the wheel every time there’s a storm or fire. We can find a solution that isn’t heavy handed and gets the job done. There may be a big national debate, but the tenor is different as a result of where we live. It would help everyone if a few more homeowners would take care of a few simple things on the to-do list before we enter that debate.”

See also:

Fire Prevention Plans: “Almost impossible unless we have a different mindset”

CO Task Force: Homeowners should pay to live in burn zones; developers/real estate industry oppose parts of plan