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Posts Tagged: Yana Valachovic

What can we learn from the 14,000 homes lost during the Camp Fire?

Shades of brown and grey cast over bricks, cement, remnants of metal roofs and steel beams from manufactured and modular homes, collapsed stucco walls, BBQs, shells of washers and driers, along with an occasional tea pot—that is what you can see in and amongst living, but singed Ponderosa pine and California black oak trees where the Camp Fire burned. How did California's most deadly fire happen and what might be done differently to ensure a better outcome? These are difficult questions that California will wrestle with for a long time to come.

 

Surviving home with recently upgraded roofing, vents, and combustible materials separated from the house. Every home surrounding this house was lost to the Camp Fire.

Last week I was able to tour some of the burned area in Paradise and Magalia to evaluate why some homes survived and others did not. This gave me a chance to look at homes that survived largely on their material selection, design details, the owner's maintenance efforts, and not necessarily with the aid of a fire crew or resident that stayed. Many of the buildings that were burned were lost on the first day or two of the fire while emergency response was focused on evacuating the communities. It will take months to make sense of this mess and tragedy, but during my tour some conditions rang true to me.

  • Wildfire is not uniform. Not all fires are the same and not all houses experience the same type of fire. When you are looking at home losses and survivors, keep in mind that each home may not have had the same fire exposure. Some homes experienced significant ember exposure, while others ignited because their neighbor's home succumbed to fire and the heat of their neighbor's house caught their house on fire, while others were protected from the wind and its deadly embers. Paradise and Magalia have blocks and blocks of nothing but foundations, but amongst these bleak conditions are a few intact or partially damaged homes that have a story to tell.
    Remnants of a burned trailer park in Paradise.
  • We saw homes that survived that had upgraded attic and foundation vents that meet the California building code for construction in wildfire prone areas. Some of these houses also included some extra efforts where vegetation and combustible mulch was virtually eliminated in the area immediately adjacent to the home. Our inspection team included UC's Dr. Steve Quarles, a national expert in fire-safe construction, who interpreted this to mean that meeting the 2008 Chapter 7 A standards, coupled with the enhanced defensible space, likely made the difference to ward off the assault of the ember-driven Camp Fire. We found evidence that burned homes in Paradise had ¼” mesh foundation and under-eave vent screens. Research has shown that these larger size screens let embers penetrate the attic and ignite the house from within. The 2008 California building code standards specify screen mesh size between 1/8” and 1/16”-inch, or vents that demonstrate their ability to resist embers and flames.
    A homeowner holds a foundation vent found in the rubble of her home. Her home was built before the 2008 construction standards and had the larger ¼ inch mesh screen size that may have allowed embers to enter her home.
  • Our tour also confirmed that landscaping plants and wood mulch placed right next to the house creates vulnerability. While looking at the rubble of a home, it can be difficult to tell what happened; however, we saw several surviving houses with broken glass or otherwise damaged dual-pane windows that experienced heat exposures sufficient to crack glass in the windows, but the home still survived during these first two days when fire crews were rightly focused on community evacuation and not structure protection. For the houses that did not survive, we can interpret that in addition to the vulnerabilities in vents or a roof, heat can easily break glass in windows, especially if those windows are single pane, and can likely created a pathway for fire to enter the houses.
    Wood mulch and landscape plants burned adjacent to this newly constructed home. Several windows were broken from the heat from this fire. The home met the new construction standards and survived, but likely would not have been damaged if there had been a 5-foot zone around the home that did not contain combustible plants or other materials.
  • Home placement makes a difference. A home at the top of a canyon or gulch can easily be overwhelmed by wildfire by taking on additional heat as the fire approaches and being blasted with embers. This is not a new concept, but the homes in the broader Paradise region were especially vulnerable when they were located above these gulches and canyons. Enhanced vegetation management is highly recommended that includes a 5-foot non-combustible zone immediately adjacent to the home. 

Our team, which also included Dr. Eric Knapp from the USDA Forest Service Pacific Southwest Research Station, has been able to do a quick analysis of home losses by year of construction in Paradise. This cursory analysis shows that many homes built after the 2008 wildfire standards were adopted were lost during this fire, however, without knowing the specific details of each home (e.g., maintenance practices, proximity to other building, etc.), these statistics can be misleading. We will continue to work through the available data to try to look for patterns, however, in the meantime, it seems clear to me that the new construction standards can reduce the probability of ember intrusion and may have helped for some homes in Paradise. This week a new study reported that complying with these standards was not considerably more expensive. Additionally, the codes that help guide construction in California's wildfire-prone areas are dynamic and will be informed by the 2017 and 2018 wildfire seasons.

Remnant charred materials called “embers” found in a lawn were the drivers of the Camp Fire. The larger size shown in this fire suggests that these were embers generated from burning buildings and not from vegetation.

For me thinking about Paradise in the abstraction was easy. Visiting it was different. The name says it all. After my visit I could understand why someone would choose Paradise or Magalia; the views are awesome, the air is clear, the forest and woodlands are amazing. I can only imagine that the community was (almost) perfect. Rebuilding a more resilient community will take considerable thought, effort, and some radical new ideas.

A well-maintained forested area in Paradise that had minimal tree mortality from the Camp Fire.

Posted on Friday, December 21, 2018 at 3:09 PM
  • Author: Yana Valachovic

Why Homes Burn and Why I'm Reminding You

Reposted from the Fire Adapted Communities Learning Network blog

 

I was nine years old when my dad's family home burned in the Oakland Hills Fire. As a country kid from one of the most fire-prone counties in northern California, I was no stranger to wildfire. Still, I remember the shock of driving through his childhood neighborhood in the weeks after the fire, seeing nothing but the skeletal remains of vehicles and homes — so different than the forest fires that I was used to back in Trinity County.

Those images came back to me a few weeks ago when I gave a presentation at a workshop in Redwood Valley, California. That community, which is in Mendocino County, suffered a devastating wildfire in October, during the same week that fires were burning throughout Sonoma and Napa counties. During the Redwood Valley Fire, nine people were killed and more than 500 structures were destroyed. Now more fires are burning in southern California, and in some ways, it seems that the human connection — the loss of lives, the loss of homes — is the defining feature of this year's fire season in California.

Redwood Valley Fire damage

Redwood Valley Fire damage. “In some ways, it seems that the human connection — the loss of lives, the loss of homes — is the defining feature of this year's fire season in California.” Credit: Lenya Quinn-Davidson, Fire Adapted Communities Learning Network

One of my close colleagues at the University of California Cooperative Extension, Yana Valachovic, has no doubt felt the human implications of the 2017 fire season. Her phone has been ringing off the hook for months because of her expertise and experience in home ignitions and home survival: concepts that people are desperate to understand and implement in light of the ongoing losses throughout the state.

In some ways, the research on home survival during wildfire is intuitive; most people understand defensible space concepts and the basics of fuels management. But there are so many ways that most of us could do better — ways that are well illustrated by my own friends, colleagues and family.

Yana talks about how even she — someone who studies this topic — stores paper bags full of her kids' old schoolwork in her attic, right next to the vents. And if you read the literature on this topic, you know that vents represent a major vulnerability during wildfire. Most homes burn from the inside out, meaning that embers make their way into the home through vents and other crevices, and they then ignite fuels inside the house. Once embers infiltrate, it's hard to slow them down — hence the photos we often see of blackened homes surrounded by green trees and intact neighborhoods.

Screenshot of Vulnerability of Vents to Wind-Blown Embers report cover

Click on the image above to access Dr. Steve Quarles' new report, Vulnerability of Vents to Wind-Blown Embers

Current research supports the use of finer mesh vent screens (typically a second screen behind the outer screen), and/or temporary vent covers during wildfire events. There is an impressive amount of information available on home venting and fire, including the desired fineness of screen meshes, the use of ridge vents and the appropriateness of unvented attics (PDF, 213 MB). Much of this work comes from the Insurance Institute for Business and Home Safety (IBHS). Steve Quarles leads IBHS's fire-related research program and has published a number of papers on this topic, including a new report, Vulnerability of Vents to Wind-Blown Embers.

Homes can also burn from the outside in, thanks again, in large part, to embers. A few years ago, when a wildfire came within a half mile of my mom's house, I found her gutters packed with dry leaves. This is a classic problem, and one that I was surprised to see at my own mom's house. How did we let the gutters fill up like that, knowing what we know? Gutters full of debris, if ignited, will provide direct flame and ignition to the edge of the roof; if the roof is not adequately protected by metal flashing, or if the gutter is below the roof edge exposing the vulnerable roof sheathing, it can be difficult to keep fire from spreading from the gutter into the house. In 2010, when Quarles was with University of California, he co-authored a great publication that discusses rain gutters, vents, roofing, decks and other home vulnerabilities (PDF, 4.87 MB).

There is also a fair amount of research on features adjacent or attached to the home — features like decks, fences and landscaping (PDF, 416 KB). Still, on a recent trip to a research station in southwest Georgia (a place known for its fire science research and active fire management), I was surprised to see that the landscaping around every building had a thick mulching of longleaf pine needles — literally one of the most flammable types of leaf litter in the world. It looked great but wouldn't be particularly helpful if a fire came through. And IBHS wildfire demonstrations, like this one from 2011, have shown that mulches and other near-home landscaping can become serious points of weakness during wildfire. (I highly recommend checking out their video demonstrations if you haven't before; they have a lab where they actually burn down full-sized homes.)

Now I know that this information is likely old news to many of you; I hesitated to write about this topic because our readership is probably fairly fluent in the research on home ignitions and survival. But the images of Yana's attic full of well-cured paper, my mom's gutters full of leaves, and the pine needle mulch at the research station in Georgia reminded me that we all have more we can do — even if we're well-versed in how homes burn. Home hardening is, of course, only one facet of fire adaptation, but this year's fires reinforced the importance of all efforts at all scales, from the vent and the gutters to the community wildfire protection plan and the prescribed burn.

Posted on Tuesday, January 9, 2018 at 4:15 PM
  • Author: Lenya Quinn-Davidson

Houses likely burned from the inside out, says UCCE forest advisor

Reposted from UCANR News

 

Fire damage from the 1991 Oakland Hills fire. Buildings can burn quickly if embers get inside and fall on flammable materials.
 

Preventing embers from getting inside may save homes

Photos and video of the Northern California communities that have been hit by wildfires this week show buildings reduced to ash. How could so many homes and businesses burn so quickly in Wine Country fires? Many houses that burned to the ground in the Northern California fires likely burned from the inside out, says Yana Valachovic, UC Cooperative Extension forest advisor for Humboldt and Del Norte counties.

Red hot embers carried on the wind can enter the attic via the venting. “In the case of the wind-driven fires on October 8, these fires created ember storms that blasted little coals into everything in their pathway,” Valachovic said. These embers also create small spot fires near the home that fuel new sources of embers.

Weather played a large role in these fires and generated a fire storm of embers that ignited grass, shrubs, trees and anything in its path. “While the landscape can be the fuse, the homes really can be the most burnable part of the landscape,” Valachovic said. “These embers likely lodged in the small spaces and openings of homes and buildings. A common location is for the embers to enter via attic venting or HVAC systems distributing little fires into the buildings.

“Embers also landed on receptive leaves, outside furniture, and other flammable materials outside the buildings that created fires adjacent to the buildings. Once enough buildings were engulfed in fire, the radiant heat of each building fire led to exposures on the neighboring buildings, creating a house-to-house burn environment.”

Embers carried on the wind can ignite dry plant material like pine needles and create more embers that may enter homes through vents.
 

Residents can reduce the risk of embers setting their house on fire by removing dry plants around the structure.

“These fires remind us that everyone in California could help the fire situation by managing the vegetation, leaves in the gutters and decks, newspaper piles, brooms and other flammable sources near to their houses now before they get the evacuation call,” Valachovic said. “If you are likely to have to evacuate soon, temporarily covering or sealing up the vents with metal tape or plywood can help harden your home to an ember storm.”

Steve Quarles, UC Cooperative Extension advisor emeritus, who spent his career studying fire behavior on building materials and around homes, created an online Homeowner's Wildfire Mitigation Guide at http://ucanr.edu/sites/Wildfire. Quarles, who now does research for the Insurance Institute for Business and Home Safety, demonstrates how embers can ignite and quickly engulf a house in flames in a video https://www.youtube.com/watch?v=IvbNOPSYyss. After the 3-minute mark, video shows embers drifting up and flying through a screened vent into the house, where they could ignite combustible materials in the attic resulting in fire starting on the inside of the home.

“If you have time to prepare your home, use the wildfire last-minute check list at http://disastersafety.org/wp-content/uploads/2016/07/IBHS-Wildfire-Last-Minute-Checklist.pdf,” Valachovic said.

Valachovic has co-authored publications in home survival in wildfire prone areas http://anrcatalog.ucanr.edu/pdf/8393.pdf and how landscape plants near homes can create more vulnerability to wildfire http://anrcatalog.ucanr.edu/pdf/8228.pdf.

Once these fires are extinguished, a more detailed analysis will be possible.

“Past wildfire events have shown that this is the common way homes in the wildland urban interface (WUI) burn, and this scenario was likely translated to the urban environment,” she said.  

Posted on Tuesday, October 17, 2017 at 9:04 PM
  • Author: Pam Kan-Rice
Tags: embers (2), home loss (1), wildfire (44), Yana Valachovic (4)

Five-foot zone free of plants can help rural homes’ fire survival

California law requires homeowners in wildfire-prone areas to create 100 feet of defensible space around their dwellings. UC Agriculture and Natural Resources (UCANR) experts suggest going a bit farther by creating a five-foot buffer immediately surrounding the home completely devoid of plants and anything that can burn. 


A foothill dwelling landscaped with a five-foot non-combustible zone. The building is also equipped with an extra large rain barrell that collects water during storms for irrigating plants.
 

Few people think about creating the non-combustible zone, said UC ANR Cooperative Extension advisor Yana Valachovic, because they are so accustomed to foundation plantings. “Plants are used to anchor the house visually on the landscape. Without them, a house can look naked,” Valachovic said.

But the non-combustible space adjoining the house may be the difference between losing it and all the contents to a wildfire versus returning to the property with the home unscathed. This extra precaution can be important, Valachovic explains, because, “embers from a distant wildfire can land on or adjacent to your house and ignite combustible items.”

In the five-foot non-combustible zone, even such common items as firewood, deck furniture, a wooden ladder, , brooms and other wooden tools should be absent during the fire season.

Rock mulch, decorative stone “hardscape,” and concrete paths can be aesthetically pleasing alternatives.

“We have to simplify our landscapes and accept less vegetation to improve fire safety,” Valachovic said.

UC Agriculture and Natural Resources is involved in fire research and education statewide, helping enhance understanding of fire's role in human communities and natural areas. A range of UC ANR publications and online tools address wildfire riskfuels impacts of forest diseases and home wildfire mitigation. UC ANR is part of the California Fire Science Consortium, a network of fire science researchers, managers, and outreach specialists tasked with improving the availability and understanding of fire science and management knowledge.

Valachovic, the UC ANR forestry advisor in Humboldt and Del Norte counties, recently hosted a webinar (recording available online) for homeowners in areas at wildfire risk, during which she said a five-foot non-combustible zone around the home increases the likelihood of home fire survival and provides several additional benefits to rural homeowners.

“If you have five feet of non-combustible area immediately next to the house, you don't have to cut back plants for siding maintenance and there's ample space for placement of a ladder to clean the gutters,” she said. “The open space also provides access for cleaning up any accumulation of pine needles and leaf litter, also a significant fire risk.”

Ten years ago, California extended the defensible space rule from 30 feet to 100. The area within 30 feet of the home should be maintained in a way authorities call “lean, green and clean.” Dry grass, leaves, brush and dead wood should be cleared. Open areas should be left between islands of vegetation in the 30-foot-zone to disrupt the path of a fire to the home. Trees within six feet of the house should be cut back or removed entirely.

Beyond 30 feet, in the extended 100-foot reduced fuel zone, fire officials ask that landowners remove dead wood, debris and low tree branches. Small trees and plants growing under trees should be removed, as they act as ladders giving ground fires access to tree crowns.

Valachovic said “fire resistant” plants can be characterized as having low growth, open structures, not holding on to dead leaves and having leaves with high moisture content. But she said no vegetation is truly fire safe.

“Landscape maintenance is essential,” Valachovic said. “All plants can burn under the right conditions.”

An initiative to maintain and enhance healthy families and communities is part of the UC Division of Agriculture and Natural Resources Strategic Vision 2025.

Posted on Thursday, March 19, 2015 at 10:19 AM
  • Author: Jeannette Warnert
 
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