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Advocate to the Board of Forestry about clear regulations to protect trees in the “Zone Zero” area within five feet of structures. Send email before Friday-March 6 to PublicComments@bof.ca.gov. Copy suggested paragraphs from this document.
The California Board of Forestry has proposed “Zone Zero” regulations to eliminate all vegetation within five (5) feet of structures, including all tree leaves and branches. With the de facto enforcement of insurance companies, that could lead to removal of many urban trees on private property and the loss of invaluable extensive tree canopy in all our communities. Tree removals will not reduce structure ignitions, so trees would be “sacrificed” for no gain. This page was written by Anne Fege, Certified Urban and Community Forester.
What are “Zone Zero” regulations and why do they matter?
The role of combustible materials within five feet of structures has long been recognized and is now named “Zone Zero.” Trees are not yet explicitly allowed in the Zone Zero elements of this code. At risk is the removal of healthy trees, that would not decrease structure ignitions but would lose shade, wildlife habitat and aesthetic values of trees. An expensive waste.
The Board of Forestry has developed two options for the inclusion of trees in Zone Zero, both with the language, “Well-maintained trees allowed, local tree protections included. Branches must be at least 5 feet away from walls and above roofs and 10 feet from chimneys. View more info about the Board of Forestry proposal and current codes. The final decision has been paused until the Board’s meeting on March 10-11, and comments can be sent to PublicComments@bof.ca.gov.
Options to comment:
- Use the form below to immediately send the public comment shown below.
- Copy and paste the public comment provided (or a customized message with your examples or concerns) and send via email to PublicComments@bof.ca.gov with the subject line, “Trees in Zone Zero” or something similar.
If you have questions before sending your email, contact Anne Fege, Certified Urban and Community Forester, anne@katestrees.org. Thank you for contributing to tree advocacy!
Zone 0 Public Comment
Using the form to the left, the following message will automatically be sent to the Board of Forestry and Fire Protection:
Zone Zero regulations need to clearly allow trees, and we support Option One for Trees “Well-maintained trees allowed, local tree protections included”. Evidence from wildfire research and post-fire assessments demonstrates that mature, hydrated trees do not pose an inherent ignition risk to structures. Large-diameter trunks and primary branches contain substantial internal moisture and require prolonged, high-intensity heat to ignite, conditions not produced by wind-borne embers. The regulations still need to require removing ladder fuels, trimming tree canopy that overhangs the roof, and cleaning leaves and needles from roofs.
Stronger guidance is needed for implementation, as our local fire departments interpret, advise, and enforce tree retention (and removal, if not well-maintained). If accurate code-based local authority is not exercised, there is great risk and already evidence that insurance companies become “de facto” interpreters and enforcers of Zone Zero regulations. Local authorities need effective educational materials for homeowners on how to harden structures.
Unwarranted tree removal will result in unintended losses in the many valued and familiar benefits of trees, including shade, cooling, lower energy use, aesthetics, social pleasures, and canopy goals in Climate Action Plans. At risk is the expensive wasteful removal of trees that don’t ignite in urban ember-driven wildfires and won’t reduce structure ignition risks. So please make it clear that structures can be “firesafe” with well-managed hydrated trees.
How do trees ignite? How do houses ignite?
What does tree biology tell us about how trees ignite? (or not)
- Tree trunks have high moisture content, covered with protective bark, and often 6 to 20 inches in diameter (dbh).
- Primary branches are 2 to 6 inches in dbh and are generally smooth or lightly textured.
- The trunk and branches are like big green firewood logs, which ignite only after burning a lot of kindling and smaller logs. Leaves are green and well hydrated, and in a wildfire would be blowing wind, embers blowing through them without landing or igniting them.
- Current regulations require branches 6 to 12 feet up from the ground to be removed, so they aren’t “ladder fuel” that could be ignited from burning ground plants and then spread to upper branches.
How can trees ignite houses? (or not)
- If the trees are not ignited (trunk, branches or leaves), they can’t and won’t ignite the structure.
- Leaves and needles on a roof can ignite from embers during a wildfire, which then ignites the roof. Existing regulations require that they be removed, and that tree branches growing over the roof be trimmed, as they will drop leaves and needles.
- Palms are a different story. Embers land in the dry fronds at the top of untrimmed palms and ignite the fronds. Winds can break off and blow the burning fronds onto other houses or palms, known as “Roman candles.
What do studies tell us?
- Scientific evidence from wildfire research and post-fire assessments demonstrates that mature, hydrated trees do not pose an inherent ignition risk to structures. References and links here.
- Large-diameter trunks and primary branches contain substantial internal moisture and require prolonged, high-intensity heat to ignite, conditions not typically produced by wind-borne embers alone.
- Observations from recent California wildfire events consistently show that trees are more often damaged by burning structures rather than serving as ignition sources for homes.
- Some studies suggest that tree canopies may intercept or deflect embers, reducing ember deposition on roofs, vents, and other vulnerable building components.
What can homeowners do to protect trees and structures?
Start by viewing two videos.
- California Office of the State Fire Marshal, “Wildfire prepared home, incorporating Zone O,” 2.5 minutes, https://www.youtube.com/watch?v=D1Wwiv4AW1k
- UC Berkeley study: Home hardening, defensible space saves double the homes in wildfires, 3 minutes, https://www.youtube.com/watch?v=iL9o8vVIZGc
Focus on “home hardening” to reduce structure ignition risks.
- Learn about the Safer from Wildfires cooperative effort of CalFire and California Department of Insurance, with Ten Steps that will qualify properties for an insurance discount. Step 2 needs to be clarified, to retain trees that are trimmed, maintained and hydrated.
- Take this Ready for Wildfire Self-assessment that guides homeowners into identifying risks and specific steps to reduce those risks in defensible space, home hardening and firesafe landscaping.
Take care of your trees.
- Keep trees hydrated (before, during and after wildfires), info at Save our Water and Trees.
- Maintain trees property. Hire an arborist.
- Remove lower branches of trees (“ladder fuels”). Remove leaves and needles from roofs. Both of these are in current PRC 4231 and outlined in CalFire’s Defensible space info.
What happens if Zone Zero codes don’t protect trees?
Local implementation is critical, as fire departments interpret, advise, and enforce tree retention/removal.
- There is considerable uncertainty about interpretation, when local authorities serve as “fire experts” in PRC 4291 (1) (C) for insurance companies to set requirements for insuring a structure.
- If accurate code-based local authority is not exercised, there is great risk and already evidence that insurance companies become “de factor” interpreters and enforcers of Zone Zero regulations.
- Locally, fire departments need to promote the Ten Steps in the Safer from Wildfires cooperative Calfire-Insurance effort, in educating residents, communities and fire officials.
Urban tree losses can have state-wide unintended consequences if residents are directed to remove trees.
- There will be great losses in the many valued and familiar benefits of trees, including shade, cooling, lower energy use, aesthetics, social pleasures, canopy goals in Climate Action Plans.
- PRC 4291 (e)(1) clearly states that Board of Forestry guidance “shall permit trees near homes for shade, aesthetics, and habitat….”
- At risk is the expensive wasteful removal of trees that don’t ignite in urban ember-driven wildfires and won’t reduce structure ignition risks.