Under Fire: How We Rebuild After Wildfires

A blaze in the Nadina-Verdun wildfire complex in British Columbia, Canada. Like many other places across the world this summer, residents of B.C. will be facing a colossal rebuilding challenge when the wildfire season is done. (Image courtesy of Tracy Calogheros, CBC News.)

In 2017, wildfires swept across Europe and North America, causing record land loss and property destruction. The 2018 wildfire season is shaping up to be just as bad. Observers, like Canadian politician John Horgan, are starting to worry “that this may be the new normal.”

For people building or rebuilding in fire-prone areas, it could be a difficult normal to adjust to. In the wake of these fires, the question is: How do we rebuild stronger after wildfires? Even more importantly, should we?

World on Fire

An infrared image of Earth, stitched together from NASA satellite footage. The red represents areas of forest fire. (Image courtesy of NASA).

The summer of 2018 has been the summer of the wildfire. Fires have swept across western Canada and the U.S. California’s Mendocino Complex Fire is now the largest in the state’s history. Outside of North America, fires have caused devastation in Russia, United Kingdom, Greece and even above the Arctic Circle in Sweden.

Why have fires become such a problem? Global climate change is one possible cause. A 2016 PNAS study showed that increasing temperatures have increased fuel aridity, or how dry a forest’s organic material is. The drier the fuel is, the easier it is for fires to start.

There is another, more direct cause: We’re building closer to the source.

Last year, California’s Tubbs Fire followed almost the same path through Sonoma County as the Hanley Fire in 1964. The damage from the Tubbs Fire was much greater because there were more people living in the area. Sonoma County is an example of the rapid expansion in the wild land-urban interface (WUI)—the area where houses border on natural vegetation. Between 1990 and 2010, the WUI in the U.S. went up by 33 percent. The number of homes in the area increased by 41 percent.

The higher number of homes in the WUI delivers a one-two punch in terms of wildfire damage. Not only does it increase the amount of damage caused to houses, it heightens the risk that they will start in the first place.

With all this working against them, how do contractors and architects go about building homes that can withstand fire?

The “Fireproof” Home

To build fire-resistant buildings, the builder first needs to understand how wildfires behave.

“Driven by strong winds, [a wildfire] will reach peak temperatures in seconds and may pass over your site and be gone within minutes, as soon as all the standing fuel is consumed,” said Murray Milne, UCLA Architecture research professor. “The problem then is secondary spot fires started on and within your home by wind-driven flames and embers. If you can design your home to withstand this massive but brief exterior attack, it has a good chance of survival.”

The first line of defence is keeping the fire from spreading to the house in the first place.

Any house in fire country needs a defensible space—an area around a building that has been cleared of vegetation and other debris that could catch fire. If there are any trees in the area, the crowns should be pruned so they aren’t touching each other or the house. FEMA’s guide to fire proofing housing suggests (heavily irrigated) grass, rock gardens, stone patios and metal patio furniture. It also recommends using hardscape features, like driveways, walkways or gravel patios, to act as a possible fire break.

FEMA’s proposed design for a defensible space. (Image courtesy of FEMA.)

After the area around the house, builders need to pay special attention to the roof. Because of its size and orientation—fire moves easily up sloped surfaces—it can be very friendly to the spread of flames. The builder needs to ensure they’re working with Class A fire resistant materials and that there are no cracks or gaps in the tiles for a hungry fire to slip through. They also need to pay special attention to any eaves, overhangs and soffits, the underside of the roof. Often, the materials used for these elements aren’t fireproof. This can be a problem since flames can get trapped under them and run particularly hot.

Best-practices materials for exterior walls include concrete, stucco, brick masonry and metal. Windows are the weakest point. Fire can either shatter the glass with its heat or dislodge flaming chunks of wood, firebrands, from the surrounding environment and send them crashing through the pane. FEMA recommends automatic roll-down metal fire doors over the windows. The doors would be held in place by a mechanical fusible link. The heat of a potential fire would melt the alloy in the link and allow the doors to roll down over the windows, even if nobody’s in the house.

Experts recommend roll-down metal doors over windows, which can be built so that they’re automatically released by fire. (Image courtesy of Owen Geiger.)

Sprinklers, both interior and exterior, are recommended. The most safety-conscious experts will advise residents to consider their own backup power generator so that, in case the power goes out, the sprinklers will still be functional.

So, we know how to build for fire. Why isn’t it always happening, especially in areas with serious fire risks?

Why We Play With Fire

Part of the reason is that fire-resistant building methods can be expensive. Fire-rated wood can cost up to twice as much as conventional wood. Tempered glass can cost up to a fifth more. For some people, especially those who are in denial about the possibility of a forest fire or who simply can’t pay to build to those standards, it can be a serious barrier.

One case study is the rebuilding of Canada’s Fort McMurray after devastating fires destroyed 1,595 buildings in 2016. A 2017 review by KPMG suggests that the rebuilding efforts are happening too quickly and don’t contain enough fireproofing measures. While the city started out with the intention to “build back better,” the push for quicker and cheaper construction overwhelmed them. Since insurance companies won’t pay for improvements over pre-fire conditions, most owners would be forced to pay for any fireproof upgrades themselves.

“This financial burden represents a significant barrier to residents, as many are unwilling or unable to pay out-of-pocket for upgraded and less flammable materials,” the report concludes. “Consequently, it is unlikely that most structures will be built back better.”

Even if houses are completely fireproofed, there’s a growing chorus of voices saying that it’s not enough.

Volker Radeloff, a forest ecologist at the University of Wisconsin–Madison, is one of those voices. He was one of the scientists behind the 2018 study that measured growth of the WUI through a combination of census data and satellite images. He believes that certain fires are inevitable and thinks municipalities should prevent building on risky lots rather than just try to perform damage control afterwards.

“We know that fires will continue, and climate change will bring weather conditions conducive to large fires more frequently in the future,” Radeloff told Scientific American.

The data backs him up. A 2016 study of wildfire patterns in the continental U.S. found that topography and building patterns were the factors most consistently related to building loss during wildfires, across all 50 states. The authors concluded, “Although [factors like] vegetation may be the most obvious and manageable aspect of wildfire risk that managers can address, fuel treatments are only a partial and short-term solution, and insufficient to address the other sources of fire risk to buildings.” Instead, they recommend government planners get involved in the process before areas are built on.

What about homeowners who have already built on risky land? Many of them are deeply conflicted about the choice of what to do next.

Vicky Spitzer was one of the Californians who lost their house in last year’s Tubbs Fire. She’s planning on rebuilding on the same site. The empty lot would have fetched too low a price, especially with the abundance on the market recently. That doesn’t mean Spitzer is entirely happy about her decision, “I think we’re kind of stupid,” she told ClimateWire. “It’s going to happen again. I think it’s kind of stupid to do it again.”