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The Woodsman: Wildfire: The Woodsman’s Home Gets a Defensible-Space Assessment

By Steve Wilent

The Woodsman: Wildfire: The Woodsman’s Home Gets a Defensible-Space Assessment

When I came across an announcement from the Oregon State Fire Marshal’s office offering free assessments of defensible space around homes and businesses, I signed up right away. But before I hit “send,” I hesitated, wondering if I really wanted to know just how well my home is, or isn’t, prepared to survive a wildfire. Being familiar with the idea of creating a defensible space, I knew the assessment would show that I have some work to do. To be honest, I like the natural landscape on my property, the 120-year-old trees and the variety of green vegetation, such as vine maple, rhododendron, sword fern, and salal. I have a five-foot or wider clear area on all sides of the house and I’ve removed small trees and shrubs near the house and tree limbs that hung over or near the structure. Would the assessors recommend doing more?

I had the answer in early April, when two folks from the fire marshal’s office visited my property: Ron Parvin, Deputy State Fire Marshal for Clackamas, Multnomah, and Washington Counties, and Alison Green, Defensible Space Coordinator. They gave me a copy of a flier, “Oregon Defensible Space For Homeowners & Renters” (you can download it and other resources at

According to the flier, “Defensible space is the buffer you create between your business or home and the grass, trees, shrubs, or any wildland area that surrounds it. Proper defensible space can slow or stop the spread of wildfire and help protect your home or business.” Or apartment building, church — any structure.
Parvin, Green, and I walked around my house and discussed their findings for eight defensible space guidelines. They later sent a report with recommendations for my property (my comments are in italics):

1) Flammable vegetation is removed from growing directly under the eaves. A minimum of five feet from the structure is recommended. Parvin and Green noted that I meet this guideline.

2) Leaves, conifer needles, deadwood, bark mulch, and other debris removed from the surface of, around, and below decks and fences. Recommend removing any needles etc. from around and, if possible, below decks.

3) Trees spaced and pruned following the example on page 2 [of the flier]. Recommend removing any tree that is feasible that doesn’t meet the guidelines. [The diagram that accompanies this article, from page 2 of the flier, shows 10 feet of space between the crowns of trees. Meeting this standard in our area is impractical in our heavily forested area: Green and Parvin noted that many local property owners would need to remove far too many trees than is feasible or aesthetically desirable. Thus, they didn’t recommend that I cut down any of my trees.]

4) Leaves, conifer needles, deadwood, bark mulch, and other debris removed from within 100 feet of the structure or to the property line. Recommend following question 2 and work further away from structure if possible.

5) Fire-resistive plants are spaced within the designated defensible space area. Grass is mowed to less than four inches. Recommend using fire resistive plant guide to replace any plants that are not. [The “Fire-resistant Plants for Home Landscapes” publication that you can download at lists several of our common native plants near my house, such as Oregon grape, salal, Pacific rhododendron, vine maple, and Woods’ rose.]

6) Firewood piles and lumber at least 30 feet from any structure. Recommendation: If possible, move firewood piles 30 feet away — currently about 20 feet. [Having firewood or lumber piled against your house during wildfire season is an invitation for a wildfire to spread to your house.]

7) Combustible vegetation 10 feet away from permanent propane tanks. Recommend removing vegetation and wooden fence away from propane tank.

8) Small BBQ tanks, not in use, are stored at least 30 feet away or in an outbuilding. Meets guidelines.
Parvin also recommended that I remove two large vine maple limbs that hang over my driveway and could obstruct a fire engine. Phew! With relatively little effort, I can significantly boost my home’s resistance to wildfire. For example, I might remove some of the shrubs out to 100 feet or more from the house. These are not highly flammable plant species, but they can burn, of course. Adding space between them, and keeping dead leaves and other debris to a minimum, would help slow any low-intensity ground fire. This is one of the most common recommendations.

“The biggest thing is keeping things that can burn away from the home—fir needles, decorative bark mulch—which is definitely flammable—and keeping some space between ground cover, between shrubs and trees. That means removing ladder fuels that could help a fire move up into the trees,” Parvin said.

Green added that defensible space assessors consider fuel continuity both vertically and horizontally. Adding space between plants and trees in both dimensions makes it harder for a wildfire to move through the area. Green said she and her colleagues do a fair amount of wildfire myth-busting.

“No matter what eco-type we go into, the first thing many people say is that they don’t want to cut down their trees. And we say, ‘well, we’re not going to make you cut down your trees,’” she said. “There is a misconception that a defensible space has to be a rock doughnut—a house surrounded by nothing that can burn, a moonscape. It really comes down to making some strategic decisions with plants, with the goal of breaking up the fuel bed to reduce the intensity of a fire.

“At the end of the day, fire-resistant does not mean fire-proof,” Green said. “We’re trying to prevent high-intensity wildfire from moving either across the landscape or up into the trees.”

Parvin said that the agency’s defensible-space assessments provide recommendations, not requirements, to manage vegetation around homes — there are no fines or penalties for failing to do so. Note that the Oregon state legislature may one day enact regulations requiring creating and maintaining defensible spaces around homes. Rest assured that The Woodsman will inform you of any such developments.
Although they didn’t include it in their assessment report, Green and Parvin recommended that I keep my gutters and roof clear of fir needles, cones and other debris. Wind-blown embers from wildfires can travel long distances and fall on homes far away. If those embers fall in gutters or roof valleys filled with dry fir needles and other materials, the house may burn even though the wildfire is miles away.

“Seventy-five to eighty percent of homes that are lost to wildfire catch fire because of ember cast. It’s not the wall of fire that people have in their minds,” Green said.

The fire marshal’s office received nearly 300 requests statewide for assessments in the first three weeks after the initial announcement on March 11.

“That’s great, but it has kept us extremely busy — in the best possible way,” Green said.

The agency, which makes frequent use of social media and public-service announcements in English and Spanish, intends to continue offering to do assessments through the month of May, which happens to be Wildfire Awareness Month in Oregon.

Want to know more? The Mt. Hood Corridor Wildfire Partnership is holding a Mt. Hood Wildfire Ready Homeowner Workshop at Welches Middle School on May 19, 2024, from 9 a.m. to 2:30 p.m. Lunch will be provided starting at 1:15 p.m. You’ll need to register at

Have a question about defensible space? Want to know how far embers from a wildfire can travel? Let me know. Email:

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