Understanding Home Ignition Zones

What is the Home Ignition Zone?

The Home Ignition Zone is a buffer around your house to reduce the likelihood of wildfire spreading to and igniting your home. Improving and maintaining your Home Ignition Zone can harden your home to withstand ember attacks and create defensible space to reduce the likelihood of flames reaching the home. The Home Ignition Zone combines three separate zones to include the house and the surrounding 100 feet.

The information provided on this page is to be considered best practice for existing homes to reduce the risk of destruction from wildfire. The Poway Municipal Code contains specific requirements for new construction. Homes identified as a hazardous fire area or located in the Very High Fire Hazard Severity Zone have legal requirements regarding vegetation management. 

Zone 0

Zone 0, also known as the immediate zone, includes the structure of the home, decks and patios, and the space within five feet of the house. Decades of research have shown that both the house and the landscape adjacent to it play a critical role in the home surviving a wildfire. It is critical to reduce the combustible materials within the first five feet to create an ember-resistant zone, designed to keep radiant heat or embers from igniting material that can spread the fire to your home. The goal is to have zero combustible material within the first five feet.

To demonstrate the importance of a zero-combustion zone, the Insurance Institute of Business and Home Safety partnered with CAL FIRE to create the timelapse video below. The video shows firefighters simulating how an ember storm can start small fires in ornamental landscaping which can then spread to the home. The home on the left uses mulch as a ground cover immediately adjacent to the wooden fence and structure while the home on the right uses crushed rock and non-combustible building materials.

Harden Your Home

Regular maintenance, small changes, and low-cost retrofits can reduce your home's vulnerability to embers. Home hardening has two goals. First, to prevent embers from entering your home and second, to utilize fire resistant materials to prevent embers from igniting small fires that turn into a destructive structure fire. 

Roofs and roofing components

• Keep roofs and gutters clean by removing all debris, dead leaves, needles, and other combustible waste.
• Check for ember resistant roofing materials and construction. Ensure roofs with asphalt shingles are in good repair and that shingles cannot be lifted by the wind to expose the wooden roof deck underneath. Ensure roofs with barrel tiles are equipped with fire stops at all edges to prevent embers being blown under the tiles. 
• Install an approved spark arrestor on all chimneys and stovepipes.
• Protect roof to wall intersections or elevation changes with metal flashing.
• For older homes that do not currently have a Class A fire retardant roof, the only long-term reliable way to reduce roof vulnerability is to reroof.

Vents

• Cover vents and other openings with 1/8-inch mesh metal screening to prevent embers from entering your home.

Eaves

• For homes with open eave construction, caulk gaps and smooth surfaces to prevent embers and hot gases from reaching vulnerable areas. 
• To prevent the buildup of hot gases and embers, enclose vents with a non-combustible material. Eaves can be retrofitted with ventilated soffit panels to create a flush surface.

Windows

• Dual paned windows with non-combustible frames are recommended to withstand the radiant heat of an approaching wildfire. For older homes that do not currently have dual paned windows, the only long-term reliable way to reduce window vulnerability is a full replacement.

Siding

• Non-combustible siding such as stone, cement board, or stucco are recommended to withstand small fires and the radiant heat of an approach wildfire.
• For homes with wooden or vinyl siding, the addition of a non-combustible skirting of at least 12 inches will reduce your home's vulnerability.

Decks and patios

• All wooden attachments should be considered an extension of the home for ember protection. 
• Ground level decks should have any crawl space or other openings screened with 1/8-inch metal mesh. 
• Elevated attachments including patio covers and second story decks should be treated like eaves. The underside of elevated attachments should be enclosed to reduce vulnerability.

Fencing

• Keep the base of any fencing clear of debris.
• Replace fencing and gates within the first five feet of the home with non-combustible materials.

Zone 0 Landscaping and Defensible Space

The goal of Zone 0 is to create an area with zero combustible materials that will not allow embers to start small fires that turn into destructive structure fires. Research has shown that the hardening of the home and the Zone 0 clearance are the most important components of home survivability during a wildfire. Many homeowners may already have established ornamental landscaping in this zone, use the points below to start making small changes towards the goal of zero combustible materials. 

Home decor and other items

• Home decor items placed within the first five feet can collect embers and bring flames closer to your home. 
• Plan to move combustible items away from the home during red flag, high fire risk days or before evacuating. 
• Replace flammable decor with non-combustible items. 
• Relocate garbage cans, boats, recreational vehicles, and personal vehicles to an area outside this zone. 
• Relocate wood piles or exposed firewood to an area at least 30 feet from the home.

Ground cover

• Utilize a non-combustible ground cover such as dirt, gravel, or pavers. The use of landscaping mulch within Zone 0 should be avoided.
• The use of synthetic lawn materials is not recommended.
• Grass or other living ground cover should be irrigated and maintained at a height of two to three inches.

Mature trees - for homes with existing mature trees in the Zone 0 area

• Trim branches to be least 10 feet above the roof and at least 10 feet from a chimney or stove pipe.
• Trim branches away from the eaves of the home and any other vulnerable areas of your home. 
• Remove vegetation from below the tree to create separation between fuels
• Consider removing trees with highly flammable characteristics.

Landscaping - for homes that choose to maintain ornamental vegetation in the Zone 0 area

• Choose plants with an open-growth structure or that are non-woody, plants with thick, fleshy leaves or that have a high moisture content, plants with little odor, and plants that do not shed bark. Refer to the City of Poway Landscape and Irrigation Design Manual (PDF) for a list of specific fire-resistant plants.
• Avoid plants that are dense, thatched, or woody, plants with dry or leathery leaves, plants that are fragrant with a high content of oil or resin, and plants that shed bark or other materials. Refer to the City of Poway Landscape and Irrigation Design Manual (PDF) for a list of specific undesirable plants.
• Keep plants separated from each other and from your home, leaving a space of at least 12 inches or 1.5 times the height of the plant.
• Plants should be limited to 16 inches in height.
• Remove plants from in front of windows or any other vulnerable areas of your home.
• Utilize planters made of non-combustible materials to create separation.
• Keep plants irrigated and maintained.

Maintenance

• Remove dead or dying vegetation including fallen leaves or shedding bark.
• Trim all tree branches to be 10 feet above the roof and at least 10 feet from a chimney or stove pipe. 
• Trim all plantings to maintain the maximum recommended height and the minimum recommended spacing.

Zone 1

Zone 1, also known as the intermediate zone, includes the area from five feet of the home to 30 feet from the home. Proper placement, irrigation and maintenance can reduce the likelihood of fire spreading from your landscaping to your home. Use the points below to create a landscape that can slow or stop the spread of wildfire.

• Remove all dead or dying vegetation from your yard including fallen leaves or shedding bark.
• Keep lawns and other ground cover trimmed to a maximum height of four inches.
• Create islands of ornamental landscaping separated by irrigated or non-combustible ground cover.
• Maintain horizontal separation between islands of landscaping. Spacing between islands of plantings or shrubbery should be two times the height of the shrubs. Spacing between islands of trees should be at least twenty feet. This space should be increased on a slope.
• Maintain vertical separation between tree branches and anything below. There should be a minimum of six feet of clearance between all tree branches and the ground. For trees with plantings below, maintain at least three times the height of the plantings to the lowest branches.
• Maintain plants in this area to a maximum height of 36 inches.

Zone 2

Zone 2, also known as the extended zone, includes the area from 30 feet of the home out to 100 feet or the property line. Proper maintenance of this area can help reduce the size of approaching flames and prevent wildfire from spreading rapidly through your landscape. 

• Remove all dead or dying vegetation from your yard including fallen leaves and other debris.
• Keep lawns, native grasses, weeds, and other ground cover trimmed to a maximum height of four inches.
• Spacing between islands of trees should be at least ten feet. This space should be increased on a slope.

Environmental Regulations

The City of Poway is home to thousands of acres of sensitive habitat and protected open space. The need for fire safety and defensible space must be balanced with the need to protect the sensitive habitat found within our community. Homes adjacent to open space or a biological conservation easement may require a home assessment by the Fire Department and a no-fee brush clearance permit prior to the cutting of any native chapparal.