A Conversation with Eric Knapp and Yana Valachovic 
Eric Knapp, of the US Forest Service Pacific Southwest Research Station, and Yana Valachovic, from UC Cooperative Extension, came by The Lookout in November to talk with me about their new paper on home losses in the Camp Fire. Our talk is live on Amanda Monthei’s Life With Fire Podcast. Their research paper is available here:
Knapp and Valochovic are both members of the California Fire Science Consortium. More information on this organization can be found here.
Zeke Lunder: Welcome back to The Lookout everyone. Today is November 8, 2021 and that means it’s been three years since the Camp Fire destroyed the town of Paradise. Paradise is about 10 miles from where we’re sitting here in Chico, California. Shortly after the Camp Fire, a couple of my friends who are fire researchers came out with me and we looked at destroyed buildings in Paradise. Since then, they’ve been doing quite a bit of research on some of the factors that helped homes survive, and other factors that took homes out during the Camp Fire.
This image, captured at 10:45 am, shows burning structures (yellow dots) in Paradise, and major spot fires taking off all over town.
Paradise, before the Camp Fire.
Paradise, after cleanup following the Camp Fire.
Zeke Lunder: I want to welcome Eric Knapp and Yana Valachovic to The Lookout. Thanks for coming and thanks for the work you’ve been doing. Can you tell us a bit about the paper you just wrote?
Yana Valachovic: First, it’s a real pleasure to be with you today. I don’t think we planned this to be on the anniversary of the Camp Fire. It was also the 30th anniversary of the Oakland Hills fire just two weeks ago. So it’s kind of timely to be reflective in this space and thinking about what a future adaptive, resilient California looks like. I just want to appreciate you, Zeke, because you took us out, got us behind the lines, and inside the fire footprint of the Camp Fire. Not so much as a study of the experience, but to open the door to a place for learning. It’s uncomfortable to look at communities, look at homes and look at everyone’s lives and treasures, but if we don’t take a moment to reflect a little bit, it’s hard to figure out where we’re going to go. What this paper starts to do is detangle some of the critical issues that have been holding us back, and what I hope we can do through podcasts like this, and through other opportunities, is to start to chart that course forward about what resilience looks like. How can we be more thoughtful in this space and really create an environment, both the landscaping, the forests, the oceans, the rivers, all of it… and where we live in this place, so that we all can survive and thrive?
Eric Knapp: This is obviously a bit of a departure for me. I do most of my work with vegetation, science, forestry and prescribed fire. But when you experience a summer like that, you know… We’re all curious people, and we want to figure out what happened. A number of us, Yan and I included, started discussing what was happening. We wanted to learn about what was threatening the homes, why we were getting a lot of questions from the media about what was going on and we just wanted to learn about what we could do better to live with fire. Part of that understanding comes from a better understanding of the mechanisms by which homes are lost.
Yana: As a scientist, we often get to design experiments, test assumptions, evaluate variables, and look for cause and effect, adding a variable in or taking it out. But when you start looking at community resiliency, it’s something you can’t do easily. You can’t build a community and a replicant community, and then burn one down to see how it performs. Right? That’s something we’ll never allow.
Paradise, as much as it was a tragedy, was also an opportunity to ask some questions about how we build, where we build, what we build with, and whether the time period of construction has an influence on how codes perform. Does slope or aspect or the quantity of vegetation make an effect on building survival? We were able to use those kinds of variables to ask some key questions about the era of construction, survivorship failure, damage in that environment, and really test some questions about whether the new building codes are making a difference.
The Camp Fire spread extremely rapidly, driven by strong east winds. This image shows the fire’s spread in the first 4 hours after ignition. Paradise is in the upper 1/4 of this image.
Zeke: Run me through the key findings of your study.
Eric: We looked at satellite data and aerial photographs after the fire. It was pretty clear, when we were on the ground, that there appeared to be some effect of a neighboring structure burning. We wanted to see how strong that effect was in relation to vegetation variables. Oftentimes with fire we think about defensible space and managing the vegetation around our houses, so we looked at both those variables and analyzed what were best predictors of whether a home survived or not.
One of the main things we found is that both the distance to the nearest destroyed structure and vegetation matter and they matter quite strongly. We were actually surprised how strong these factors were. In a lot of the statistical models, it’s actually the distance to the nearest destroyed structure and the number of destroyed homes you had within 100 metres of your house. Those were the most important factors
Zeke: …suggesting that the houses in the densest neighborhoods, the places that have the smaller lots were more susceptible?
Yana: Yes and no, and I think this is an interesting point. If you sort of step back, it’s really a community effect, this idea that we’re all in this together, and we’re only as strong as our weakest house. When you get a neighboring building ignited, the ability of the surrounding vegetation and buildings to withstand that heat begins to degrade. What we’re talking about is how the proximity to an ignited home affects the neighboring home. Basically, when there’s more homes involved in fire nearby, there’s a greater and stronger prediction that the subject home is going to fail.
I think about COVID. In essence, it’s basically a study of epidemiology: when there’s more people around you that are carrying the disease, the likelihood that you may contract the disease increases significantly. So it’s kind of the same, but what I think this really says is that we all need to work together as a community. Our neighboring homes affect our own survival in a way that we’re maybe not aware of. We can’t really armor our way out of this just by ourselves. We need to lift everybody together.
Zeke: Once a house is on fire, and there’s no firefighters there to put it out, it’s likely it’s going to take out the neighbor’s house.
Photo by Owen Bettis for Deer Creek Resources.
Yana: It has a high potential. There are ways that we can look at those particularly vulnerable elements on buildings to be able to harden them. That’s the home hardening concept, to create greater heat resistance qualities. A regular annealed window can’t handle as much heat as a tempered glass window can. If your garage is detached from your building, or you have a bunch of sheds around your property, where we have windows that face those garages and sheds, those are more likely to fail. I live in a pretty rural area where a lot of people have wood sheds. If that’s close to your house, and you’ve got a window facing it, then increasing the strength of that window and that wall would be warranted.
Eric: One of the things that we found in the statistics is regarding the distance. There was a threshold. If you had a structure burning within 59 feet, you had a much lower probability of survival. That might not necessarily be a house like Yana said. That could be a shed, that could be a garage. Oftentimes with these other structures, we don’t really think of them as something we need to fire harden, but that all can take out a house.
I think what’s important is that, so far, a lot of our focus has been on vegetation, managing the surrounding vegetation and defensible space. But in reality, the homes and the sheds and things that we have on our properties, they dwarf the amount of fuel that’s in the surrounding landscape. It’s important to consider all aspects. Not that vegetation doesn’t matter, because it also was an important factor in the models, but it wasn’t as important.
What we actually measured was the canopy cover of trees, but the way the fire happened, and it’s seen on a lot of fires, in this landscape a lot of the trees survived. It wasn’t so much living green vegetation where the fire was going from crown to crown. The association, probably, was the fact that when you have higher canopy cover, there’s probably more fuel on the ground, which is carrying fire.
Trees play an important role in our landscape and I’ve seen a lot of trees needlessly cut down out of fear of a fire hazard. In understanding how fire burns, the hazard, I think, is what the trees produce: the leaves that fill up gutters and roof lines.
Zeke It’s the pine needles that can carry the fire. You mentioned that when you were out there today, you just saw a ton of leaves on the ground. When we think of the Camp Fire happening in November, there was all this fresh black oak leaf fall and pine needle fall from the windstorm that could carry a surface fire.
The Camp Fire was driven by high winds, dry vegetation, and long-range spotting.
Yana: That’s right. Knowing that one might be rebuilding or might have a house in a forest environment, I’m fine with. The idea is how to look for those places where materials can accumulate and harden them. Or figure out a way to design a building so that you don’t create those accumulation points. When you have roof to wall intersections, you’re asking the roof to perform really well and then you’re asking the wall to perform just as well as the roof, but it can’t unless you do some additional work to make that intersection work better. The simpler the roofline, the less accumulation points. If it were me and I was rebuilding in Paradise, which I would happily do, I would be thinking about creating the simplest structure I could, so I don’t have those places of accumulation.
Zeke: There’s even something as simple as just having a really simple roof without a bunch of dormers and gables.
Yana: Exactly. And not having these weird intersections and roof planes. You know, this is really a complicated look, which is very popular in our modern culture right now, but it’s maybe not setting us up for the best success. I’d also be adding gutter guards of a non combustible material. You want those gutters because they keep your siding in good shape, because otherwise the water runs off and hits the lower siding and begins to rot out the lower portion of the building. But they also accumulate material, so if you can keep all those pine needles and oak leaves and whatever you might have in the environment out of those gutters, the better.
Zeke: What are some other things? We talked a lot about the importance of keeping a clear distance five feet right off of your house. You’re basically saying that a lot of small fires that were moving across the landscape, could catch the houses on fire. And then once the houses were on fire, they’d catch the neighboring houses on fire. I think one thing that was eye opening for me after the Camp Fire was this idea that there won’t be a fire department there when a community burns down. A lot of us have become used to thinking that we just need to prepare enough defensible space so that firefighters can safely save your house. That’s the whole root of the term “defensible space,” is to make it safe for firefighters to come save your house. But you’re saying that we need to assume that during a fire like this, there won’t be any firefighting. The firefighters will be working on saving people’s lives and evacuating people, so we really have to think about those little things like a small fire burning up to your home.
Yana: Exactly. Following up on your idea, defensible space is a California term and it’s written into our code. I think you’re exactly right. I think we thought of it in a defendable space mode, where you would modify fuel behavior such that if there was a fire coming through trees, it would lay down to the ground and you could put an engine and a crew there. And they could have flame links that were something that they could attack directly and it would be safe.
But what we’re realizing with these wind-ignited fires or distributed fires, is that you end up with embers and other material coming over and across your defendable space. Suddenly, the building itself is vulnerable! When you have these extreme events with a lot of wind behind them, where our fire crews are working on evacuation, as they should. That should be the first priority. To get everyone out who needs to get out.
How do we design and retrofit our buildings, so they’re most able to be strong in that moment when there isn’t a crew there. For me, there’s three three main priorities. The roof needs to be in really good shape, it needs to be well maintained, and it needs to have someone regularly looking at it. Then the vents all need to meet Chapter 7A standards, which basically mean they are ember and flame resistant so they can handle heat exposure and embers moving and being thrown at them. So they’re not penetrated and you don’t end up with something inside your house that’s burning. And third, is what we now terming in California “Zone Zero,” which is that the first five feet out from the building needs to be of non combustible material. Underneath the deck and around the building. Sort of flip-flop where you put your gardens. Pull those out a little farther and put your walkways closer to your house, for example. That way, you’ll be able to see your plants better when you’re looking at it from the inside of the house. You can look out and see them as opposed to trying to lean over and look down. It’s kind of a win win. So those three: the roof, the vents and those first five feet. That’s the biggest barrier to your home surviving.
Zeke: It’s a little tough in some of these mountain communities, because where you have snow that comes off your roof, you end up putting all this stuff right up against your house so won’t be buried. This kind of requires us to rethink. I think one of the reasons we end up with so many sheds scattered everywhere is that having covered space is a premium, especially if you can’t put it right up against your house. So I thought it was interesting what you said about the need to build a shed to this fire resistance standard. I think the problem is that a lot of us hillbillies have built sheds out of whatever we had on hand, pallets or leftover barnwood or whatever.
Yana: As long as it’s safe from the elements, that’s how we thought about it. All of that affects our survival, and I think that’s exactly the point. It’s a paradigm shift for us to rethink this moment, in this time and how we build. I field the question a lot, you know, should we not allow for construction in a community like Paradise? Where would we allow construction in California? Every part of California is vulnerable to wildfire at some time or another? What do we do in earthquake country? We adapt, and we build smarter.
Zeke: Do you have any idea of some basic costs to take your typical home that might have been in Paradise before the fire, and retrofit it to a standard that might have held up better?
Yana: Sure. There’s a good study that was produced by Headwaters Economics that looks at new construction, because that’s a known environment, right? You can plan out an existing building and be able to evaluate it. It’s about a 3% additional cost to meet these new standards. On a $250,000 home that’s relatively modest overall.
There’s a number of things that people can do to retrofit their existing structures. If they’ve got a little bit of know-how and a little bit of muscle power, much of it is quite affordable and not a huge barrier. If you can implement that non combustible zone around the house, then you may not need those flame resistant vents. You can just use a ⅛” metal mesh screen to upgrade your existing events. That can be tacked on the inside or the outside. It depends on how your vents are set up, but that’s a very low cost kind of retrofit.
Zeke: One thing I noticed when we went out there, after the fire, was just that you just didn’t see a lot of old, shaggy kind of houses. After the fire, almost all the houses we saw were newer or really well maintained older homes. What did you guys find, as far as age of structure in survival?
Eric: We definitely saw the home-age effect. The homes built before 1997, about 11% of them survived and homes built after ‘97, somewhere in the neighborhood of 35 to 45% survived. So there was a big effect of home age and some of that has to do with how our building standards have changed over time. There’s more cement board siding used, just newer…
Yana: The roofs are still in their period of performance. Right? If you put on a new roof right now, you’ll get a 20-40 30-40 year lifespan, right? You’re buying that degree of longevity and durability. Going back to 1997, we’re only 25 years, 30 years out from there, right? That’s still within the period of performance. When you look at older buildings, you don’t know whether or not people had done the appropriate modifications and upgrades that needed to happen to that roofing.
Eric: Just based on what we saw out there and what I saw on pre-fire images, it’s also just our propensity to collect stuff on our properties over time, more sheds, more stuff against the house. And just maintenance. Embers love rotten wood. Over time, these houses became more vulnerable. Also, the older houses in Paradise tended to be closer together.
Zeke: Why do embers love rotten wood? What’s the mechanism?
Eric: Well, it just is much easier for an ember to actually ignite rotten wood.
Yana: Think about it. How do we start a campfire? Do we start with big rounds of wood? Or do we start with small kindling? Right? Well, we usually start with newspaper and some kindling. And then you put the bigger pieces of wood.
When a board is rotten, it’s got a lot more places of penetration. It’s already becoming more like kindling than it is like a piece of firewood itself. There’s more nooks and crannies, there’s a little more air contact, you know, there’s more places for a little bit of dryness to occur so that ember can ignite.
Zeke: One thing that occurred to me after we were driving around in Paradise is that when you have a leak in your house, then the fire can get in. I think a lot about wooden boats. If you have a wooden boat and you don’t maintain it, it’ll leak and it’ll sink. Houses are kind of the same. If you have cracks in the eaves or if you have kind of loose corners on your gutters or your fascia boards, those are just places that the fire can get in and sink your house. Man, all that maintenance is really expensive, you know? So there’s this tie to people’s well being and their ability to afford that. When you buy a house in a place like Paradise, you really have to think about this. This regular maintenance isn’t just kind of a luxury or something that makes your house look good. It’s this necessity to survive.
Yana: I think people are looking for simple solutions right now. My mom will say to me, “Well, I have a metal roof, I’m fine.” Or someone will say, “Well, I’ve got stucco siding or I’ve got Hardie plank.” You can’t really buy your way out of this. Right? It’s between the materials and how they were installed, how you’ve maintained them, and then your attention to all the small details. It’s all of that and a coupled effect with looking at the whole environment. That’s what it takes for us to shift and think about the vulnerabilities that we may experience. Maybe it’s flames coming directly at the building. It may be radiant heat, where you’ve got heat transfer through the air. Or it may be these embers.
We have to figure out our structures for all those types of fire exposures and on our game all the time thinking about it. We live in earthquake country. We talk about earthquakes and we talk about the things we need to do to be ready for that. But we haven’t, I feel, as a culture gotten to that place where we sort of uniformly talk about fire, and what we do. What’s our game plan for the weekend? How do we invest and make sure that our properties are in the best condition possible? A lot of it is inexpensive. It’s just really paying attention to it and being willing to be proactive when we see something go south a little bit and need some extra maintenance.
Eric: Going back to one of your points you made earlier, is the shift in thinking of living with fire. We need to live as if fire was inevitable. I think in the past, we have lived and built our infrastructure and done stuff around our home without thinking about fire because the fire department is just down the corner,
Zeke: Right? There’s a hydrant on the corner.
Eric: Just that shift, I feel, may lead to people considering fire in their decisions. And some of the stuff, like Yana said, is quite simple. We saw some of that today when we were up in the Camp Fire. There’s just a lot more use of rock rather than bark mulch right up against houses. Instead of people building their new wood fence right up to the house, so that the flames can reach up into the eaves if they catch fire. These fences are sort of ember magnets. They’re using a section of metal, a wrought iron, to disconnect that fence from the house. We definitely saw some positive things today that make me feel better about the rebuilding up there. That’s a good trend.
Yana: Overall, I’m really optimistic that we can do better with a little more knowledge, a little more power. Our building officials being on board with us and our supply companies being available and understanding of what we need and kind of a whole community infusion of thought and idea. How long did it take for us to really figure out how to deal with earthquakes? It took many generations, and in school we all… drop, cover and hold on, and practiced drills and thought all about that. When it comes to fire, we really haven’t done that much. But with that power, that knowledge, I think we can propel ourselves in a really successful way if we just pay a little more attention to these details. People figured out how to live in hurricane country and tornado country. We can figure out how to live in fire country.
Zeke: That’s optimistic. I gotta say. I know you guys’ job is to try to make this stuff accessible. I look at some of these places with your findings where the houses are the fuel and we talk a lot about burning fuels and reducing hazardous fuels. There are some places where that would mean removing houses, if the houses are the fuel that is spreading the fire from house to house. In these places where we have these layouts, I feel that it’s inevitable that we’re gonna burn down a lot more towns like Paradise and that we need to be thinking more about how we rebuild in a more sensible fashion.
Yana: I agree with you. We’re in a period of adjustment. I don’t think the next five years look remarkable. It’s going to take a while to get there. We are seeing a $1.5 billion investment come from the state of California. That is huge. We spent $5 billion on fire suppression in California in 2020 alone. In the last 10 years, we’ve burned down 14,000 structures and 171 lives have been lost. What does it take for us to really make that kind of investment? Well, it’s taken a lot of tragedy and a lot of loss that none of us want to go through again to get to that place of investment in California.
Now, can we do the same with the federal level? What if we just spent dollar for dollar the same amount on suppression as we do on prevention? Right now, we’ve just had crumbs in the toaster in terms of the amount we’ve spent on prevention, right? Not that pouring money at it is the only solution. I mean, pouring money is part of the solution, but even if a bazillion dollars showed up today, we don’t have the qualified workforce. We don’t have the trained professionals, we don’t have the infrastructure it takes to process fuels to make the building products that we need. There’s a lot of room for improvement. I can go down that pessimistic line pretty easily. There’s a million barriers.
On the other hand, what I think we suffer from is a lack of vision of what is possible, and so you see a lot of defeatist discussions. Everybody’s gone like, “Well, hell. I don’t know.” If we can’t chart a course forward, then we’re not going to go anywhere. We’re gonna stay in that same place. I mean, I’ve got kids, you’ve got kids. I want to believe that we’re an adaptive thinking society that can reflect on where we come from and make better decisions.
Zeke: I agree. I think that people need to understand the seriousness of the challenge ahead, in places like Nevada City and Grass Valley, where we’ve got huge concentrations of old structures. In places where the physical layout of the town makes it impossible to achieve vegetation management at the scale necessary. People need to understand that they need to do everything possible. It’s not something that we can just kind of sit back and think, “Okay, we’re gonna put some new screens on our vents and gonna be alright.” You know, there’s not anything fundamentally different about Nevada City than there is from Paradise,
Yana: Or coastal towns. All of California is in a vulnerable situation and really all of the Pacific Northwest is. Look at Sedona, Arizona. There are so many communities that have challenges.
Eric: I tend to be more of an optimist than a pessimist, but I think the data that we found gave us reason for some optimism. If it was just a random thing up there, if nothing really would have mattered, we wouldn’t have seen such a strong effect of the simple variables in the model. The fact that there were some really strong explanatory variables gives you the sense that there’s things that can be done to change the outcome.
Zeke: Not being pessimistic, but being realistic… if the critical factor is the spacing between houses, then there’s not a lot we can do about that. We can harden each house and make sure that it’s less likely they’re going to catch on fire, but we can’t really thin houses.
Eric: You can prevent them from catching fire or make that such a low probability that it’s no longer an issue… as the housing density.
Zeke: I think it points out that we need to address that a lot of the problems we have that make these neighborhoods susceptible to wildfire are social problems of poverty and lack of capacity to cut brush or hoarding. Or just this deep poverty that results in people with five cars in their yard and 20 years worth of recycling on their deck.
Yana: Let’s come back to the fact that we’re all in this together, right? How do we help us become a more resilient and healthy community? I think this may become a conversation point. Maybe this is the point where we actually are not divided by politics, and not divided by socioeconomic class, but understand that there’s a lot we can do to support each other.
I grew up in very rural California, where everybody was an individualist but yet we all still had some social norms in terms of looking out for each other and making sure so-and-so was still getting food and whatever they needed. We looked out for each other. I think fire is something that can unite us. For those that can’t, then there’s a whole other side, right? There’s those that can’t and so what can we do to help them? Make sure that they have a better alert system, that they have ways to get in and out, that they have someone looking after them.
Paradise has a lot of that story, about people that didn’t get alerts and couldn’t get out. How do we also lift those folks up and help them to the best of our abilities? There’s a lot of work to do in that space and that’s not what this paper talks about, necessarily. But for people that are not in a place where they’re ready to embrace these kinds of changes, then they need to figure out an alternate strategy about when to leave early. So is it those red flag warnings that are frequent? You live in a place where you get them a lot, but that puts you on notice that today might be the day. You go through that mentally every day, when you’ve got a red flag warning. Okay, today might be the day and I’m ready to go, and maybe I’m ready to go early.
Zeke: I think one thing that stands out in Paradise is that even though defensible space didn’t necessarily help save all the homes, all that cumulative defensible space that people have done saved thousands of people from dying in their cars. When you look at how much vegetation grows on the ridge and how much reduction had happened, just from everyone cutting a little bit of brush, we really did change the outcome of the fire.
This image shows by 10:45am, every major route out of Paradise was being impacted by the Camp Fire. Many of the homes destroyed in Paradise weren’t taken out by a wall of flame, rather, they burned when embers from other burning homes started small fires next to them, or the radiant heat of a nearby burning building caused them to catch fire.
Yana: You got safe evacuation routes out for the most part. I think what both Eric and I were struck by today is driving around and realizing how many trees are still there and that it still feels like a forested community, for the most part. There’s a few places where it got a little hot and took a few trees down more than I would have expected, but it’s pretty much continuous vegetation cover. A lot more than I would have expected.
Zeke: Do you have any closing thoughts on how we get this kind of information out to people and make it less academic and more approachable?
Eric: Well, we wrote a scientific paper, but we hope that it was written in a way that is accessible to a broader audience. Part of that is to come on shows like The Lookout and try to explain our results, not in a scientific way, but more of a conversation.
Zeke: I appreciate you coming on and talking about it.
Yana: We appreciate the invitation. Thank you.