Chief Kevin Revilla and Wildfire Mitigation Special Duncan Allard led a tour to teach and demonstrate wildfire risk assessment on Dec 7, 2024.
These are the notes from their tour.
Background introduction
80 to 85% of houses burned in a wildfire are due to embers. In the case of the Paradise fire, the bulk of the houses burned several hours after the wildfire went through the town, because of residual embers.
Our primary danger is a wildfire coming from Tilden Park during strong Diablo (NE) winds, that occur primarily in fire season, Aug through Nov, peaking in Sep and Oct. When a strong Diablo wind occurs, Berkeley Fire sends patrols in the hills. While we cannot expect to withstand a full wildfire directly reaching our houses, it is possible for us, as a neighborhood, to resist the ember fires that will likely be the primary cause for house fires.
So, for us, the biggest danger is ember fires originating from the E or NE during strong Diablo winds, that is, the winds blowing from Tilden Park. At the same time, we live on top of a ridge and fires often spread uphill. Thus there is some danger, not as probable, that during Westerly winds a fire could start in the homes below us and spread to our streets.
When fire departments analyse fire propagation, they find out that the ease of propagation is radically decreased when neighborhoods organize as Firewise neighborhoods. The effect is so strong that it impacts where and how fire departments deploy their resources and fight wildfires. [Implied: if we want the best protection from Berkeley Fire Department, we should be active as a Firewise neighborhood and improve fire prevention around us].
Firewise is not an enforcer, but a persuader. We, the audience, must function as educators and fire inspectors within our neighborhoods, and help our neighbors understand the risks that are present in our environment. In this tour, Chief Revilla and Inspector Allard will give us the tools to understand and assess risks as we walk around a neighborhood, looking at houses around us.
Since becoming aware of the Firewise effect, Chief Revilla has changed the way he looks at neighborhoods and wildfire prevention. Now, as he walks around, he looks at houses and landscapes from a Firewise point of view with a critical eye, from home hardening to gardening and vegetation management.
The wildfire dangers are based on three elements: weather, topography, and fuel. We cannot do anything about weather and topography, but we can remove the fuel. THIS—is our job.
Embers are the main enemy. 80-85% houses burning from wildfire burn from ember fire. If you remove the fuel and control the embers you remove the bulk of the danger from wildfire. Controlling ember fires IS POSSIBLE.
Conducting a Fire Risk Assessment
The way to do risk assessment is to walk around the neighborhood, and to assess each household in a systematic manner, starting from the top (the roof) and go down. Bear in mind that insurance companies have stricter requirements than the Berkeley Fire Department. When you are making repairs or renovations to your home, consider the insurance and fire department standards.
Is the roof a class A (fire resistant) roof? Class A asphalt shingles, metal, built-up gravel, all is class A. But wood/wood shingles roofs, even treated, while pretty, will not resist a fire. Those who tell you they can “treat” it and make it fire resistant, Chief Revilla is very doubtful that it will remain so for more than a few months (same for treating siding).
Is the roof clean of debris?
The eaves: are their undersides enclosed by non-combustible materials? For any houses that have open eaves with roof overhanging, leaves and flammable material that collect underneath may easily ignite them. The regulations require that the eaves be boxed in. Check with a fire safety professional about other options that would follow fire regulations and house insurance regulations.
The gutters: are they metal or plastic? Must be metal.
Are there metal gutter guards on the gutters? Plastic won’t do the job. You also want metal gutter guards.
Are the windows multi pane tempered windows? Anything else won’t likely resist.
Please note that, in the Paradise fire, windows that were all vinyl just melted and fell off, letting the fire invade the house.
VERY IMPORTANT: are the vents screened with metal 1/8" or 1/16” screens? This is critical.
- suggestion Another alternative is Vulcan vents. Vulcan vents melt closed as a feature, but the drawback is that they must be replaced every time they have been approached by high heat and they are costly.
Under the eaves are vents: are they meshed?
Under the eaves are vents: are they meshed?
Please note that, in the next few weeks, the Fire Department will be giving out free metal mesh to all houses East of Grizzly Peak.
Siding: is it concrete (e.g. Hardyboard or concrete board) or combustible, such as wood or vinyl? If combustible, is it in good shape? If combustible, are the bottom 6” to 12” of each wall non-combustible (concrete)?
Note: “fire resistant” paint, like roof treatment, will not last.
Garage doors and doors: are there any gaps under or around? They should have good rubber stripping.
Now a look at vegetation management.
The first 5 ft, around the house, typically referred to as zone zero, are the most critical. A state-wide ordinance is coming out soon and will be very strict. Chief Revilla used to be pretty tolerant of what could be done in this zone, but, after having seen the research (check IBHS literature), he has also become really strict. In Zone Zero you want absolutely no combustibles.
Do everything you can do to limit fuel in zone zero. Absolutely remove all dead and dying vegetable matter: that is the MOST important. Do not leave wood mulch. Do not leave plants. Remove absolutely everything combustible.
Wood mulch: Replace with pea gravel, volcanic rock or regular rock.
Wood fences: most of our houses have wood fences coming all the way to the house. Remove them away from the house, at least for the first five feet. Change them to metal if you can.
If you have doormats or combustible furniture, remove them whenever Diablo winds are blowing, and open your wood gates to limit the ladder effect.
Do whatever you have to do to keep zone zero, 0-5 ft, in good shape. If you have plants growing in there, try to keep only plants with broad, thick, waxy leaves: they are likely to have a lot more water and be less combustible. Keep the low limbs cut to make sure the fire cannot easily go from ground to plant, and clear the ground under everything. But most important is dead and dying matter: remove it! Remove anything that could be used for kindling to start fire.
Decks: most likely your deck is attached to the house. It is considered part of the home, probably a wood deck. You want to replace all wood boards with non-combustible surfaces, such as concrete, hard landscaping or interlocked metal surfaces. Do not store anything combustible under the deck. You could also put flashing where the deck is attached to the house to limit fire risk.
Note: tropical IPE wood deck is less combustible but it is still nixed by IBHS and best to retrofit with metal flashing or non-combustible boards
Next zone is zone 1, or intermediate zone: 5-30 feet.
You want your plants to be healthy, and have them in clusters, and have nothing in between, not wood mulch. You want clusters because you want to break the continuity of fire: break ladder fields.
Ivy: if fire gets into Ivy it will smolder. Same for wood or rubber mulch. It slowly burns then eventually gets to your house and burns it up, so best remove it.
Big valuable trees that you cannot remove: limb up your trees at least 8 ft, so as to stop the vertical fire ladder. Take out combustible vegetation under shrubs or trees.
Zone 2, 30-100 ft out: that is where you want a woodpile if you have one. If you have a woodpile, think how you can make it more resilient? Maybe non-combustible cover etc?
Looking at Michel’s house (1030)
the biggest vulnerabilities:
In the 0-5 ft zone: wood fences coming right to the house
is in the 5-30: wood fences covered with climbing vegetation (jasmine) that goes all the way to the ground. Climbing plants, even over metal mesh, are a significant vulnerability
Discussions
Hedges: limb your hedges to as to remove the bottom 4” and be able to see and remove dead material at the bottom
Tree discussion: what trees are more or less vulnerable? Inspector Allard discussed the fact that, in many cases, such as oaks and eucalyptus, it is not so much the tree itself but the very high need for constant maintenance that is the issue: both oaks and eucalyptus constantly drop burnable material that is critical to keep on removing all the time to destroy fuel on the ground. With these kinds of trees, what we need to do is limb them well so that they are not close to the house, limb them up so that they are no within 8 ft of the ground, and constantly remove the accumulated burnable material.
Inspector Allard asked us to look at a house next door, and come up with a fire assessment: Greg W did a great job! Inspector Allard then discussed bang for the buck, suggested different possible approaches, and compared their cost effectiveness. It was quite remarkable to see his very cost effective choices. His three first targets were (a) a small woody shrub laddering from the ground to an unprotected window, wood mulch in the 0-5ft area, and tucking stucco chimneys where the shingles leave a bit of space around them.
Fire Mapping: again, with Firewise there is an incredible decrease in the probability of fire getting into the city, so we are being strategic in doing that together. “You guys” (that is us) paying attention to that as a group makes a big difference to whether we as a fire department are able to allocate resources to defend this neighborhood.
Other notes
- When doing rodent control consider what can be done for fire screening at the same time
- When you do any remodel, consider the impact on fire. You may be able to do things very cost effectively that will greatly increase your fire hardening
- Use the city chipper program which is free most of the year to get rid of green combustibles
- Cheryl Drinkwater of Diablo FireSafe Council is a great source for home hardening tips
- Have a look at the City of Berkeley website for fire hardening contractors, as well as the Berkeley Fire site, which also has some links to the Berkeley Firesafe Commission.
When we get together: have an outside hangout, do group prevention activities, talk Firewise and build this group!
Appendix: Chief Revilla’s handout in PDF format
CONDUCTING_A_FIREWISE_USA_WILDLAND_RISK_ASSESSMENT_KevinRevilla.pdf (60.9 KB)