Defensible space protects a home from a wildfire’s flame front, embers landing near the home and starting fires, and radiant heat from things burning nearby. It also protects the nearby vegetation from a fire originating within a house. While CA Code 4291 requires all residents to have 100 ft of defensible space (including a 0-30 ft lean, clean, and green zone and the 30-100 ft reduced fuel zone), recent research demonstrates that a fire resistant structure and an additional 0 to 5 ft no fuel zone greatly improve a home’s survival during a wildfire.
Why no fuel within 5 ft of a structure? Embers can land near a structure and catch things on fire. These nearby fires may ignite a home through direct flame contact or radiant heat. Learn more
What is flammable and should be eliminated from 0-5 ft? ANYTHING that can burn, like trash cans, wooden fences, brooms, furniture cushions, mulch, dead and living plant materials, cars, etc.
What is the Home Ignition Zone?
Reproduced with permission from the National Fire Protection Association, copyright © 2019, NFPA, Quincy, MA. All rights reserved. For more information on the referenced subject, please go to www.nfpa.org.
0-5 ft: No fuelAB
5-30 ft: Lean, clean, and green
30-100 ft: Reduced fuels
100- 200ft: Reduced fuels if near slope, or heavy shrub and tree cover
A The 0-5 ft zone also extends along the driveway evacuation route.
B Scientific recommendations are for no fuel in this zone. This may not be possible for some people; a well-maintained irrigated lawn or widely spaced herbaceous plants that are less than 5 inches tall may be acceptable.
The latest research and observations show how homes ignite due to embers and radiant heat. Science shows that it is important to start your efforts with the house, and then to work on your landscaping from your house out to make it a defensible space.
This zone hasn’t been recognized until recently, but is likely the most important zone. Embers can land in this region and catch fuel on fire. This no fuel zone includes attachments to the home, like decks, and extends 5 ft.
- Remove all fuel, like trash cans, wooden fences, brooms, mulch, plants, leaves, needles, wood piles, twigs, stored items, etc.
- If removing all fuel is not possible, remove fuel within 5’ of vents, glass, doors, or deck.
- If plants present, maintain plants free of dead or dying wood, branches, shrubs, etc.
The goal of this zone is to have discontinuous fuel and to limit the total amount of fuel. This reduces the amount of potential radiant heat the structure may be exposed to.
- Remove all dead and dying plant materials
- Keep lawns green and mowed 4” tall
- Create discontinues fuels with driveways, walkways, patios, and groups of a few plants
- Remove ladder fuels under trees, > 3x plant height *
- Prune trees up to 6-10’ from the ground; For shorter trees do not exceed 1/3 of tree height.
- Space trees to have a minimum of 18’ between crowns. *
- Remove branches within 10’ of chimney or stovepipe outlets.
- Relocate wood piles > 30’. While fire resistant tarps are allowed by state legislation, there is little evidence that they work. It is best to move the pile further from the house.
*Additional distance needed on slopes
The goal of this region is to reduce fire behavior by keeping flames on the ground and reducing how quickly the fire spreads.
- Keep lawns and annual plants or grasses mowed to 4” tall
- Reduce ground litter and debris <= 3”deep
- Remove dead plant and tree material
- Space tree canopies >= 12’ apart if in 30-60’ zone*
- Space tree canopies >= 6’ apart if 60-100’ zone*
- Clear 10’ around wood piles to bare mineral soil
*Additional distance needed on slopes
Modifications in this region are only necessary if hazards like steep terrain, dense shrubs, close tree canopies, and/or a lot fuel leading up to tree canopies. Follow recommendations from the 30-100′ zone.
Legally required from house out to 100′:
- Remove logs or stumps, or isolate them from vegetation
- Bare mineral soil 10′ around outbuildings and propane tanks
How to start the 0-5 ft no fuel transformation:
- Removing foundation plantings can be a difficult decision for residents, and there can be disagreements between household members.
- Discuss how this zone is important to prevent home ignition from embers, and acknowledge that this may feel like a big change.
- Bare mineral soil is the cheapest option
- Invest in other landscaping
- Create plantings further away from home
- New 0-5 ft zone landscaping ideas
- A path to easily walk around house and deck
- Portable planters that you can easily remove during fire season
- A well-maintained irrigated lawn is acceptable
- Springs bulbs that are pruned back before fire season
- If you choose to not remove fuel immediately, prioritize the following:
- Remove fuel near windows, vents, and deck
- Remove highly flammable plants and all dead materials
- Make plants non-continuous
- Trim plants away from house gradually to allow time to process the change
- Insurance Institute for Business and Home Safety https://ibhs.org/risk-research/wildfire/
- National Fire Protection Association https://www.nfpa.org/Public-Education/Fire-causes-and-risks/Wildfire/Preparing-homes-for-wildfire
- University of California Cooperative Extension https://ucanr.edu/sites/fire/