Burning Down a House to Show How to Build for Wildfire Defense

By | March 20, 2019

After only a year into his job as CEO and president of the Insurance Institute for Business and Home Safety, Roy Wright is setting the place on fire.

The IBHS conducted a demonstration in early March simulating an active wildfire for media and guests by casting embers at a structure inside its massive test chamber in Chester County, S.C. The test structure was a small house built and landscaped on one side as a wildfire-resistant structure, while the other side was created with common building and landscaping materials used when wildfire resistance is not a consideration.

A set of giant ember generators showered the structure with chunks of hot particles. Within two minutes a flame had ignited. Inside of five minutes ignition of wood mulch occurred, then the next vulnerable layer lit up, moving up the siding into the eaves, inside the attic vent area, and then total desolation of one side of the structure

“What the demos showed is that you can build in a way to defend against these wildfires,” said Wright.

IBHS has learned that during wildfires, as many as 90 percent of homes and buildings damaged or destroyed are first ignited by embers or other fires set by embers, and not the main wildland fire front.

The organization stresses that there are practical, affordable steps many home and business owners can take to help reduce the risk posed by these flying embers.

Wright, who assumed the role as head of the research and information arm for the insurance industry in April 2018, was previously deputy associate administrator for insurance and mitigation at the Federal Emergency Management Agency (FEMA). He’s held posts with the U.S. Department of the Interior and the Bureau of Land Management.

Wright spoke with Insurance Journal about the difference the right building materials and landscaping can make in resisting wildfires. This has been edited for brevity and clarity.

Insurance Journal: Can you talk about your role with IBHS and about the March wildfire demonstration?

Roy Wright: Just under a year ago I joined the Insurance Institute for Business and Home Safety. I have spent, not just this last year, but the preceding couple of decades, focused on the impacts that severe weather have, the way that they disrupt lives, displace families, and drive financial loss, and IBHS offered me an opportunity to join an absolutely amazing team where the science drives that resilience. We do a lot of work on hurricanes and wind-driven rain. I think we, in many ways, are viewed as we’ve written the book on hail.

But this past month, we’ve been focused on the wildfire dimensions. Clearly, we’ve had catastrophic events play out in both 2017 and 2018, largely in the California context. Although, if you go back over the last decade, you would see wildfires from South Carolina to Tennessee, Colorado Springs, Texas all play into that same conversation. So, we had the science. We did quite a bit of the work on ember transport here. We’ve looked at defensible space and how flames spread.

So, this month we looked particularly at what does it look like to see that speed of ignition from embers. Most folks don’t fully realize, because they’ve watched on TV a fire, but flames spread. That flame coming up against the side of your house, that’s only responsible for about 10 percent of building ignitions. The other 90 percent are from embers. Embers can be the size of a fingernail. They can be the size of a whole. But they can also be the size of a hand, or the size of the entire expanse of your hands.

We looked at that, and so this particular event looked at a duplex, built side by side, where on one side we have a well-built home that has made the right choices as it pertains to wildfire defenses, and the other side using more conventional approaches. So, you start down at the very top of the house, the way that the eaves are done. So, on a well-built home, with a fire defense, will have those eaves that are closed versus open eaves.

You look at fiber cement board for siding versus wood shingle. You look at dual-pane tempered glass windows versus a single pane. You look at the way that the decks are constructed. And then you start looking at things related to that defensible space. What do those elements begin to look like?

We put that on full display. We turned on the ember generators, so this test chamber, which is the size of an airplane hangar, with turbines that are each six feet across, we use those to really rev up all the way to a Cat 4 hurricane. In this instance, we kept that down at 12 miles an hour.

IJ: What did the demos show or prove?

Wright: What the demos showed is that you can build in a way to defend against these wildfires. You watch the video of this home, the same amount of embers are hitting the good side, the gray side, of the house, as is hitting the wood shingles. On the good side, that defensible fire approach withstood just as much force of fire as the house that caught on fire.

So first and foremost, you can build this way. Secondly, the importance of defensible space, that first five feet, how you deal with your mulch, whether you’re dealing pine straw or wood, which is the worst answer, or you’re dealing with rock, but then you also begin to look at where are the bushes, where are the hedges at, because those can feed the fire.

When things lit up, yes, we saw the mulch catch fire, but the piece that really began to fan this flame up was a small hedge bush there at the corner of the house. That corner point is one of the most vulnerable places on the house. The stark relief showing you what you can do from a retrofit perspective, maybe more importantly what you can do for new construction, is on display.

Secondly, we got to show people what happened. So many people who evacuated during these fires in 2017 and ’18, showed back up and had to sift through the ash. And they don’t really understand the story of how that occurred. And I think this has given folks the images they need to be able to understand that. Hopefully, from where I sit, that turns to driving even better behavior, better choices, and better construction.

IJ: You mentioned building materials. Can you give a little bit of depth on that? Better materials, worse materials?

Wright: Yeah, so let’s start from the ground up. First, we deal with the kind of mulch that goes around the house. The best materials from a fire defense perspective are going to be some kind of rock mulch, some kind of rounded rock that can sit around there. You can still grow things with the right kind of space.

Depending on what part of the country you’re in, oftentimes people choose wood mulch, leaf mulch, sometimes even pine straw as the mulch that they lay down. It helps guard against the weeds that they don’t want coming up around their house. Yet, what they don’t appreciate is they’re inviting that ignition to happen right there.

Staying there on the ground, we deal with the bushes and the other kind of hedges and things that you would put around your house. They need to be 5-feet away, not up against the house. If they were to catch, you want them to be able to catch and not ignite the structure.

I look at decks. It has a lot to do with the materials they’re constructed out, how the joists are spaced, because the embers can come in and lodge between each one of those joists or boards. Maybe even more important is what’s directly underneath that deck that can also ignite and fan that flame up through.

I then turn to windows and door closings. You need dual-pane windows. For the same reasons you would need them for energy (conservation), you want to see that also play out because that will also guard against that type of temperature differential and help guard against the window cracking. I look at the door. You want a fiberglass door, not a wood door. The wood door catches.

We then look at the siding. Siding, you’ve got some options that are there. Particularly, in wooded areas, and people look at cabins as well as the way the construction is done quite a bit in the Northeast, folks love that wooded shingle look. It is the worst thing that you can put on the side of your house. You’re far better to put a fiber cement board on the side of your home.

What’s important, and this is important in new construction, that fiber cement board is actually cheaper to install, and a far safer way to approach fire defense. I then go up, you look at the eaves, sometimes called the soffits, that area, that overhang of your roof. You want to see that area closed in so that you’re not seeing the joists protrude out. Those open eaves allow the embers that pick up and move to fly and lodge themselves inside the attic space.

Next, I’m going to look at the attic vents, and, frankly, these are the same things we look at in terms of venting below grade areas as well. What you want on those attic vents is a way that when the heat kicks up, that they literally melt shut so that those embers aren’t coming inside the attic where they can create quite an explosion.

Finally … across the roof itself, you pay attention to the kind of debris, or various kind of organic material, that can gather near dormers, right up against the side there, because as that material sits there over time, it becomes dry and susceptible to catching on fire.

And then finally, those gutters that sit around. Are they metal versus the plastic, PVC approaches? Those PVC approaches will melt in and of their own right. And then secondly, what’s in those gutters? You want to make sure those gutters are cleaned out when you’re dealing with a major rainstorm so that the water flows where it’s supposed to. Similarly, you’ve got to do that. You do not want leaves and other organic material to accumulate there.

IJ: Do you think enough people associate the IBHS with wildfire safety and prevention?

Wright: There’s a set of people who do. Primarily, we act as an amplifier of information. So, we pose these pieces and work first with the insurance industry so that they’re pushing them out through their companies and agents, down to their policyholders. Those agents are usually some of the most trusted actors in a community and supporting homeowners. And so, we want to make sure that they have the information to act on it. We then do push out, through our disastersafety.org website, information to community officials as well as homeowners.


Topics Catastrophe Natural Disasters Wildfire Construction

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