How to protect your home from wildfires’ windblown flaming debris

<span class=A photographer stands in the rain of blazing embers during a fire in California in 2019. Josh Edelson / AFP via Getty Images“src =”–/YXBwaWQ9aGlnaGxhbmRlcjt3PTcwNTtoPTQ3Mw–/ – ~ B / aD05Njc7dz0xNDQwO2FwcGlkPXl0YWNoeW9u / https: // /YXBwaWQ9aGlnaGxhbmRlcjt3PTcwNTtoPTQ3Mw–/–~B/aD05Njc7dz0xNDQwO2FwcGlkPXl0YWNoeW9u/”/ >

When firefighters tried to protect homes near Lake Tahoe from one of the largest fires in California, they fought the wind-blown embers that kept starting small fires some far from the line of fire.

Also known as a fire blight, this ember was a powerful and dangerous reminder that protecting homes is more than avoiding a wall of flames.

Fires are pieces of burning material that break off from burning vegetation or structures and are carried through the air. They become a problem especially when heat and drought dry out grasses and trees and the wind increases. Homes and other buildings are at greater risk if dry fuels such as leaves, needles, or wood chips are on or near the building.

This risk, and how it can easily be overlooked, crystallized for me in September 2020 when my parents were told to prepare for evacuation when a fire approached their Oregon home. I have studied forest fires for years, especially how they spread through arsonists. But she carried out this threat.

This is what house protection looks like

I wasn’t worried about a wall of flames reaching my parents’ house – they had a lush and green garden that was unlikely to ignite. Instead, what worried me was whether my parents were prepared to be ignited by fires.

Fires can travel over a mile in the wind and can be a major cause of fire spreading. In the Tahoe region, for example, firefighters were not only able to concentrate on the main line of fire in the summer of 2021 – they also had to patrol after point fires.

I used a leaf blower to remove possible sources of ignition from my parents and some neighbors. I removed dried leaves in gutters and needles in roof valleys and watered the dry mulch near houses.

I wondered if a burning match or matches could start a fire in one place? If so, the potential fuel must be removed. In every home I visited, I found places where arsonists could ignite potentially combustible materials despite the homeowners’ best preparations.

The story goes on

What surprised me at the time was how little time people spent preparing for arson, even though they went to great lengths to protect their homes by watering the site. I realized that my parents and their neighbors, like many of us, envisioned protecting homes to prevent a wall of flames from reaching their homes. Little did they know that in some cases the greater threat could be blown in by the wind.

Three steps to arson-triggered fires

Fire scientists speak of point fires, which occur in three steps: how fires are created, how they are carried by the wind, and how they land and ignite fuel. Firefighting scientists, including those in my research group, are actively studying each of these steps to better predict and ultimately reduce the risks posed by arsonists to communities.

Fire burns are created by burning vegetation or structures. The sizes of the fires can vary, but can be as little as a few millimeters square.

Fire blight can come from burning pieces of bark, branches, cones, or needles when the source is forest fires. In city fires, brand marks can come from roofs, cladding, chipboard or other combustible materials.

Often times, over the past two decades, efforts to study the origins of fires have focused on quantifying the number of fires that land in particular locations when trees or other plants are burned. More recently, researchers have been working to estimate the total number of fires that are set free when objects are burned.

A burning fir tree with a white square around it.

In order to estimate how many fires a fire could cause, we placed fireproof squares around burning trees and shrubs such as Douglas fir and mugwort and collected the fires that had landed. By determining the total number of fires burns per unit of mass of the tree or shrub on fire, we can incorporate data into computer models to estimate the total number of fires started in a fire and how they spread. Ultimately, we hope that these models can be used to better understand the risks associated with forest or city fires.

Much research has focused on developing models that will capture the physics of firebright transport, or where fires are most likely to land. The manner in which arson burns in transit is an important factor. Fires can flames or smolder. Both can cause new fires.

The third step is igniting fuels – such as fences, mulch, and needles – after the fires land. Researchers are studying the warming potential or temperature of fire fires. Understanding this information is critical to implementing building codes and standards, as well as best practices to better protect homes. We’re also working to better understand what properties of fuels determine if they ignite.

The scatter plot compares the number of fires per mass with the tree height.  Taller trees had fewer fires.

How can homeowners reduce the risk?

So what can homeowners do to protect themselves from the risk of point fires?

First, start by changing your attitude towards preparation, not if but when a fire will occur nearby. I admit that as a homeowner who lives near a forest, I allow pine needles and leaves to pile up on my roof. I apologize for having time to prepare in a real fire. However, when I consider preparing for “when a fire” is around me rather than “if,” it makes me feel more urgent and responsible.

Second, people in areas at risk of fire need to educate themselves about possible sources of ignition. Note that fire-prone locations are expanding. My parents’ home has not been at risk of fire in the 30 years they lived there – until 2020. One source for finding out how to check a home’s risk is from the National Fire Protection Association.

Certainly, at least humans must remove combustible material from or near homes. In addition, they should consider sources of ignition from structures such as decks and ensure that arsonists cannot be drawn into homes through ventilation ducts or other methods. Attaching grilles to windows and over ventilation ducts with 1/8 inch holes can be a simple, inexpensive, and highly effective way of preventing arsonists from entering a home.

Third, act consistently to monitor and eliminate sources of ignition, such as needles or leaves, which may gradually build up over time. It is often possible to remove the debris with little effort, but it requires constant monitoring and prioritization of the removal.

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Certainly, actions to investigate, test and then remove sources of ignition from arson will not prevent all fires from spreading to homes. But these steps will save many homes and help reduce the risk for firefighters and communities.

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

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

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