How To Protect Your Home From Burning Debris From Forest Fires

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<p>As firefighters tried to protect homes near Lake Tahoe from one of the biggest fires on record in California, they battled windblown embers that kept starting new small fires, some well away from the line of fire.</p>
<p>These embers, also known as brandons, were a powerful and dangerous reminder that there is more to protecting homes than avoiding a wall of flames.</p>
<p>Brandons are pieces of flaming matter that break away from burning vegetation or structures and are carried through the air.  They become particularly problematic when heat and drought dry out grasses and trees and the wind picks up.  Houses and other structures are at greater risk when they have dry fuel, such as leaves, needles or wood chips, on or near the structure.</p>
<p>That risk, and how it can easily be ignored, crystallized for me in September 2020 when my parents were ordered to prepare to evacuate as a fire approached their home in Oregon.  I have studied forest fires for years, especially how they spread through brandons.  Yet this threat made it real.</p>
<h2>What does the protection of a house look like?</h2>
<p>I wasn’t worried about a wall of flames reaching my parents’ house – they had a lush, green yard that was unlikely to ignite.  Instead, what worried me was whether my parents were ready to be ignited by embers.</p>
<p>Burning embers can travel more than a mile in the wind and can be a major cause of the spread of fires.  In the Tahoe area, for example, firefighters couldn’t focus only on the main fire line in the summer of 2021 – they also had to patrol for spot fires.</p>
<p>In my parents and many of their neighbors, I used a leaf blower to eliminate potential sources of ignition.  I removed the dried leaves in the gutters and the needles in the roof valleys, and I watered the dry mulch near the houses.</p>
<p>I wondered if a lit match (s) fell in one place, could it start a fire?  If so, the potential fuel had to be removed.  In every home I have visited, I have found places where the brandons could potentially ignite flammable materials, despite the owners’ best preparations.</p>
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What surprised me at the time was how little time people spend preparing embers, although they go to great lengths to protect their homes by watering the land. What I realized was that my parents and their neighbors, like many of us, were planning to protect homes like preventing a wall of flames from reaching their homes. They did not understand that in some cases the greatest threat could be carried by the wind.

Three stages for fires started by brandons

Fire scientists speak of point fires as occurring in three stages: how brandons are generated, how they are carried by the wind, and how they land and ignite fuel. Fire scientists, including those in my research group, are actively studying each of these steps to be able to better predict and ultimately reduce the risk to firebrand communities.

Brandons are generated by the combustion of vegetation or structures. The sizes of the brandons can vary, but can be as small as several square millimeters.

Embers can come from pieces of bark, branches, cones or burning needles if the source is a forest fire. For urban fires, brandons can come from the roof, siding, particle board or other flammable materials.

Over the past two decades, efforts to study brandon generation have often focused on quantifying the number of brandons that land in particular places when trees or other vegetation burn. More recently, researchers are trying to estimate the total number of brandons that are released when objects burn.

A burning fir surrounded by a white square.

To estimate the number of brandons a fire generates, we placed squares of fire-resistant fabric around burning trees and shrubs, such as Douglas-fir and sagebrush, and collected the brandons that landed. . By determining the total number of brandons per unit mass of the burning tree or shrub, we can incorporate data into computer models to estimate the total number of brandons released in a fire and where they spread. Ultimately, we hope that these models can be used to better understand the risks associated with forest or urban fires.

Much research effort has focused on developing models that capture the physics of how embers are transported or where embers are most likely to land. The nature of the burning of embers during transport is an important factor. Brandons can be flaming or smoldering. Both can cause new fires.

The third step is the ignition of fuels – such as fences, mulch and needles – after the brandons have landed. Researchers are studying the heating potential or temperature of brandons. Understanding this information is essential to implementing building codes and standards and best practices to better protect homes. We are also working to better understand what characteristics of fuels determine whether they ignite.

The scatter plot compares the number of embers per mass to the height of the tree.  Larger trees had less brandons.

How can homeowners reduce the risk?

So what can homeowners do to protect themselves from the risk of one-off fires?

First, start by changing your mindset regarding preparedness, not if, but when a fire occurs nearby. I admit that as a homeowner living near a forest, I let pine needles and leaves pile up on my roof. I make the excuse that I will have time to prepare myself in a real fire. Yet as I consider preparing for “when a fire” is near me, rather than “if”, I feel more of a sense of urgency and responsibility.

Second, residents of fire-prone areas should educate themselves about potential ignition sources. Note that fire prone locations are expanding. My parents’ home had not been threatened by fires in their 30 years of living there – until 2020. One resource for determining how to audit a home’s risk is the National Fire Protection Association.

Certainly, at a minimum, people should remove flammable materials from or near homes. In addition, they should take into account ignition sources from structures such as decks and ensure that brandons cannot be carried into homes through ventilation ducts or other methods. Placing screens on windows and ventilation ducts, using 1/8 inch holes, can be a simple, inexpensive, and very effective way to keep embers out of a home.

Third, act consistently to watch for and eliminate sources of ignition, such as needles or leaves, which can build up gradually over time. Often it takes little effort to remove debris, but it does require constant monitoring and priority removal.

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Of course, taking steps to educate, audit and then eliminate the sources of ignition of brandons will not prevent all fires from spreading through homes. But these measures will save many homes and help reduce risks to firefighters and communities.

This article is republished from The Conversation, a nonprofit news site dedicated to sharing ideas from academic experts. It was written by: David Blunck, Oregon State University.

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David Blunck received funding to study branding and ignition from the Joint Fire Science Program (project number 15-1-04-9) and the National Institute of Science and Technology (70NANB19H164 and 70NANB17H281).


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