Editors’ Note: Yana Valachovic is the County Director – Forest Advisor for the University of California Cooperative Extension in Humboldt and Del Norte Counties. Yana is passionate about helping communities learn to live with wildfire. She is a registered professional forester and scientist whose skills and interests cover a broad set of natural resource fields, including fire protection issues for the built environment. Here Yana shares an account of a recent visit to Paradise, California while researching impacts and recovery three years after the Camp Fire.

Without intention, I found myself in Paradise, California, on November 8th, the 3rd anniversary of the start of the Camp Fire. I had planned to spend the day there with my colleague Eric Knapp, USDA Forest Service Fire Ecologist, to take a few photos and look at how the rebuilding process is going.

The sun was out, and the skies were dotted by pre-storm altocumulus clouds sending their warning that a storm was on the way. As we drove into town, the street was lined with American flags in anticipation of Veterans Day. The flags added to the day’s significance as there is much to remember and grieve. Most of the signs of the fire are gone, dead and hazardous trees are removed, damaged buildings have been repaired. Places, where destroyed businesses and homes have been cleared, are marked by shallow depressions exposing the red soil where foundations once sat and contractors and trucks are everywhere. The air was clear and there was an ever-present hum of saws, hammers and people working in the background.

Burned homes, debris and damaged trees have been removed throughout the town. Lots are vacant, rebuilt, occupied with manufactured homes or people are using motor homes and other temporary structures to start to build back lives destroyed by the fire. Before the fire, coast redwood trees were commonly planted as landscape trees. These trees sprout and form new branches giving a sense of renewal, as shown in this photo. (Photo credit Y. Valachovic)

Paradise had numerous mobile home parks that were particularly vulnerable to wildfire. This 2018-2021 photo comparison shows the amount of materials that had to be removed. These locations now wait for a new future while landscape plants such as St. John’s wort (in the foreground) begin to grow back. (Photo credit Y. Valachovic)

Eric and I recently finished an analysis of the factors that influenced home survival in the single-family homes in Paradise during the Camp Fire, and our paper was published in the October edition of Fire Ecology. Eric said to me on the drive yesterday that when we started this analysis project, he wondered whether strong effects would be found, given the inherent randomness of fire and the many variables at play. We were frankly surprised that we did in fact find strong statistical signals that can help us all adapt our homes and environments to fire exposures.

This led us to a good discussion point—does this give us a reason for hope? We both concluded that having clear scientific evidence does fill our optimism buckets. Still, we know that the challenges to change are significant. However, between growing public awareness of the risks, increased state and federal funding, changing policies and codes and human interest in self-preservation, adaptation and survival of our built environment to fire has a much better chance now than it did just a few years ago.

Paradise is like many western towns. It was built over many decades, with the bulk of its homes developed during the 1950s to the 1980s when the cognitive risk of wildfire was much lower. Paradise is a retirement town, a bedroom community to Chico, and a place I would choose to live. The views are amazing, and the region’s Ponderosa pine and California black oak stands provide shade and comfort.  Paradise had had some close calls with wildfire in the past, and Butte County’s Fire Safe Council and other groups were working hard to reduce understory forest fuels. All of this work made a difference, especially in the evacuation process as some streets were safer to travel on, and there was a planned refuge area where evacuees sheltered as the fire passed around them.

From a researcher’s perspective, what caught our eyes about Paradise were the 2018 Camp Fire’s burning conditions. The fire passed through and around the town in a very short period of time under sustained winds. With emergency response centered around saving lives, a home surviving was in large part the result of the condition of that home, its immediate surroundings and luck, rather than firefighters intervening. This made it more like a controlled experiment where the fire variables were held relatively constant. Additionally, the large number of homes (140) affected in this tragedy were constructed after the 2008 adoption of exterior building codes for homes located in the wildland-urban-interface (WUI). While we are acutely aware that to study Paradise involves studying real people’s loss and grief, we did not want to miss the learning opportunity that this fire provides all of us to better prepare our homes, towns and communities for future wildfire exposures.

Key lessons from our study of the Camp Fire

We are all in this together

Our study found a strong community effect. One of the biggest drivers of home loss in the Camp Fire was the heat radiating from the large number of structures that burned. Over 73% of homes destroyed in Paradise had a structure burn within 18 m (59 feet).

Distance to nearest destroyed structure and the total number of destroyed structures within 100 m (328 feet) were consistently the strongest predictors in our analyses. This photo shows how adjacency affects building survival. Burning structures produce substantial radiant heat, igniting adjacent homes or breaking glass in windows, allowing flames and embers to enter the home. Nearby burning structures can also be a significant source of embers. (Photo courtesy of Waldo Air)

The distance to the nearest destroyed structure or the total number of destroyed structures within 100 m (328 feet) was a primary predictor of home loss. This is because the exposure to the heat of a nearby burning structure can easily break glass in a window. Once the glass is broken, embers or flames can enter the house. This means that the condition and proximity of an outbuilding or a neighbor’s home can have a significant influence on a building’s survival, given the radiant heat exposure from a neighboring building burning.

This finding suggests that while denser developments, built to the highest standards, may potentially protect subdivisions against direct flame contact of a vegetation fire, density becomes a detriment once buildings ignite and radiant heat loads increase.

Homes are fuel too

Most of our work towards managing fuels has been focused on wildland fuels, but the homes themselves are fuel too, and our defensible mitigations need to address the vulnerabilities to this fuel source as well. In the Camp Fire, burning homes appeared to catch neighboring trees on fire more than flaming trees directly impacting homes.

An aerial image from Paradise illustrating the amount of heat released when buildings burn and nearby trees. Houses built amongst wildland vegetation (intermix) survived at a higher rate (29%) than houses built in more of a subdivision arrangement with wildland fuels nearby (interface, 16%). Average pre-fire overstory canopy cover within 0–30 m (0-98 feet) was similar for intermix and interface homes (42% and 43%, respectively), but pre-fire overstory canopy cover within 30–100 m (98-328 feet) of the structure was higher for intermix than interface homes (49% vs. 42%, respectively). If proximity to wildland fuels had been the dominant driver, we would have expected a greater percentage of loss in the wildland urban intermix. (Photo courtesy of Deer Creek Resources)

That being said, our analysis found that tree canopy cover was also associated with home survival, with a higher probability of home survival where tree cover was less than 53%. We speculate that this was because trees drop leaves and needles; these deposits can be in places where spot fires from ember ignitions can ignite homes. More trees means more debris.

Being in Paradise on November 8th, we noted that the fall colors were in full display, and the oak leaves were falling everywhere.

Oak leaves drop in the fall and collect on roofs and gutters and are easy to ignite when embers are moved through the wind. Noncombustible gutter guards can be installed to help keep the leaves out of the gutter, protect the vulnerable roof edge, and prevent fire from impinging on the roof’s decking. This newly constructed home in Paradise has effective use of cement walkways around the home to create a 5-foot noncombustible zone to protect the house from future ember exposure and direct flame contact. (Photo credit Y. Valachovic)

Trees provide critical shade from the summer heat, but have gotten a bad rap when it comes to fire safety. To have the amenities trees provide without undue fire hazard, the key is to clean up the leaves and dead wood trees produce. This includes keeping roofs, gutters and garden beds adjacent to the structure and spaces under attached decks, free of leaves. Perhaps easier said than done, but there are some tools to help, such as installation of noncombustible gutter guards, as well as ensuring that combustibles such as woodpiles, landscape mulch, wooden planters and woody plants are away from the 5-foot perimeter of the house and attached decks, both to make it easier to clean up the leaf and needle drop, but also to make sure there is little for embers to ignite, giving a home a fighting chance to survive.

Construction practices are helping

We also found that the age of the home was a significant factor in predicting survival. Only 11% of single-family homes built in or before 1996 survived, compared with 39% of homes built after 1996. But to our surprise, the key year wasn’t 2008, when California Build Code for Wildland Urban Interface (WUI) construction standards was adopted. We did not detect a significant increase in survival for homes built from 2008 to 2018, under the new building code, compared to homes constructed during an equal time period (1997 to 2007) immediately preceding the adoption of the new code. However, houses built during the last two decades (and on both sides of the code adoption) resisted wildfire better than older homes, indicating an overall improvement in common construction standards and the performance of building materials.

Home survival increases with time. Homes built before 1997 fared poorly, with only 11 % surviving, compared with 39% for homes built after 1996. Our research found a 73% probability of survival when homes more than 18 meters (59 feet) away from a destroyed structure, had < 53% canopy cover in the 30-100 m (98-328 feet) zone around the building, were built after 1973, and were on slopes < 8 %. Only 7.5% of single-family homes in Paradise met this condition.

As our colleague in the research, Steve Quarles, reminded me, “It is important for Californians to understand that homes and immediate surroundings need to be well-maintained to resist embers, survive extended radiant heat exposures and minimize direct flame contact. The findings from this study will help California’s Building Code evolve. Building codes get better with time and new data.”

So, where is the hope in all of this?

To me, it is critical that we think and work together. We need to look out for each other, especially when we live in the WUI. If a neighbor’s home is lost to wildfire, my home may go down as a result, or if my home succumbs, my house may take the neighborhood down.

I know I have work to do on my house and yard, but I also know it’s time to get the community together to help each other out! It’s time for a work party to harden our homes by installing vents that protect the house from flames and embers, putting on gutter guards to better protect the roof edge, upgrading windows to tempered glass to resist radiant heat exposures and cleaning up combustibles around our houses and outbuildings. I know that sounds like a lot all at once, but we have to start somewhere, and at least we have a pathway forward of actions that we know can make a difference.

I am frequently asked if I would build in Paradise or other locations with recent fire activity. My answer is yes, we have a lot of good evidence to show us how to build wildfire-resistant homes, which restores my faith in living in a landscape with frequent fire!

For more information:

• Knapp, E.E., Valachovic, Y.S., Quarles, S.L. et al. Housing arrangement and vegetation factors associated with single-family home survival in the 2018 Camp Fire, California. Fire Ecology 17, 25 (2021). https://doi.org/10.1186/s42408-021-00117-0
• Reducing the Vulnerability of Building to Wildfire: Vegetation and Landscaping Guidances: https://anrcatalog.ucanr.edu/pdf/8695.pdf.
• Fire Resources and Information from University of California Cooperative Extension: https://ucanr.edu/sites/fire
• Insurance Institute for Business & Home Safety’s Disaster Safety Hub: https://disastersafety.org/wildfire/
• NFPA Firewise USA Information: https://www.nfpa.org/Public-Education/Fire-causes-and-risks/Wildfire/Firewise-USA/Firewise-USA-Resources/Research-Fact-Sheet-Series

California Building Code Chapter 7A WUI construction

• http://www.fire.ca.gov/fire_prevention/fire_prevention_wildland_codes
• https://osfm.fire.ca.gov/divisions/fire-engineering-and-investigations/building-materials-listing/bml-search-building-materials-listing/

* * * *