Home Ignition Zone

What is a Home Ignition Zone?

The concept of the home ignition zone was developed by retired USDA Forest Service fire scientist Jack Cohen in the late 1990s, following some breakthrough experimental research into how homes ignite due to the effects of radiant heat. The HIZ is divided into three zones.

The Home Ignition Zone is a buffer of up to 200 feet around your house. It is the defensible space that you can cultivate as a safety bubble to protect your home. Maintaining the Home Ignition Zone can slow or stop the spread of wildfire, defend your house from fire and embers, and protect firefighters who are working to save your home.

The National Fire Protection Association (NFPA) divides the Home Ignition Zone into three sections: the Immediate Zone, the Intermediate Zone, and the Extended Zone. Other sources may refer to these sections differently; for example, FEMA refers to these areas as Zone 1, Zone 2, and Zone 3.

To view and download the Western Fire Chiefs Association’s Home Ignition Zone Preparation Checklist providing key elements in all three zones.

Home Ignition Zone (HIZ):

The NFPA (National Fire Protection Association) Firewise USA program provides a framework for homes to survive wildfires by focusing the Home Ignition Zone (HIZ), a system of three (3) zones that manage ignition risks from radiant heat and embers. Check your home using the “Reducing Wildfire Risks in the Home Ignition Zone” and the “Home Ignition Zone Checklist” to ensure your safety.

Facts: Experiments, models, and post-fire studies have shown homes ignite due to the condition of the home, and everything around it, up to 200 feet from the foundation.

Homes and the surrounding area are vulnerable to these three ignition sources:

Embers: These burning pieces of airborne wood and/or vegetation can be carried more than a mile through the wind. They can cause spot fires and ignite homes, debris, and other objects. Embers can penetrate and smolder in woodpiles, patio/deck items, vents, roofs, and debris-filled gutters.
Surface Fires: These can be low or high intensity fires that burn through live or dead grass, ground debris, and small trees and shrubs. They can ignite houses and attachments like fences, decks, and porches.
Crown Fires: This extreme type of wildfire burns in the tops of trees, spreads by radiation and convection, and is heavily influenced by wind. Crown fires generate embers that can travel more than a mile and create spot fires beyond the main fire.

Immediate Zone (0-5 feet) – Zone 1

The first area of the Home Ignition Zone is the house itself and the space within 0-5 feet of the structure. The Immediate Zone is the most important area to protect when your home is at risk of a wildfire. A fire does not have to be close to flammable materials to spread. If the fire is large enough, radiant heat can ignite combustible materials from as many as 100 feet away.

Make sure there are no flammable materials in the Immediate Zone during wildfire season. Clear out plants, firewood, propane, paint cans, or anything stored against the house or under the porch.
Clear debris from roofs and gutters, as embers can land and ignite these areas.
Explore some of the ways to ‘harden’ your home against wildfires.

The home and the area 0-5’ from the furthest attached exterior point of the home; defined as a non-combustible area. Science tells us this is the most important zone to take immediate action on as it is the most vulnerable to embers. START WITH THE HOUSE ITSELF then move into the landscaping section of the Immediate Zone.

This is the most critical area and requires the highest level of non-combustible materials to prevent ignition from windblown embers, which are a major cause of home fires during a wildfire.

The house itself: Cover any openings with 1/8-inch metal mesh screening, including attic and crawlspace vents, and areas under decks and porches.
The roof: Clean gutters and roof surfaces regularly to remove flammable debris like leaves and pine needles. Ensure all shingles or roof tiles are intact.
Ground cover: Use non-combustible landscaping materials like gravel, pavers, or concrete. Replace flammable mulch with rock.
Vegetation: Remove all plants, dead leaves, and pine needles.
Combustible items: Relocate any flammable items, such as firewood piles, outdoor furniture, and garbage cans, to a safe distance outside this zone.

What to do:

Clean roofs and gutters of dead leaves, debris and pine needles that could catch embers.
Replace or repair any loose or missing shingles or roof tiles to prevent ember penetration.
Reduce embers that could pass through vents in the eaves by installing 1/8 inch metal mesh screening.
Clean debris from exterior attic vents and install 1/8 inch metal mesh screening to reduce embers.
Repair or replace damaged or loose window screens and any broken windows Screen or box-in areas below patios and decks with wire mesh to prevent debris and combustible materials from accumulating.
Move any flammable material away from wall exteriors – mulch, flammable plants, leaves and needles, firewood piles – anything that can burn. Remove anything stored underneath decks or porches.

Intermediate Zone (5-30 feet) – Zone 2

The second area of the Home Ignition Zone is between 5-30 feet from the house. In the Intermediate Zone, you can build out your home’s defensible space with landscaping to prevent fire from spreading from your yard and plants to your house.

Create breaks in vegetation with patios, flowerbeds, and walkways.
Cut back overgrown areas, especially beneath trees, and remove ladder fuels, which are low tree branches, taller shrubs, or climbing plants that can carry fire from the ground and up into trees.⁵ Prune trees so branches are 6-10 feet from the ground.
Any tree canopies should end at least 10 feet from the house itself, and trees should have more space between them the closer they are to the house.⁶

5-30’ from the furthest exterior point of the home. Landscaping/hardscaping- employing careful landscaping or creating breaks that can help influence and decrease fire behavior

The goal in this area is to use strategic landscaping to create “fuel breaks” that slow and interrupt the spread of fire.

Ground cover: Keep lawns and grasses mowed to a maximum height of 4 inches.
Tree spacing: Prune trees to create both horizontal and vertical separation. Create at least 18 feet of spacing between tree crowns, which should be increased on steeper slopes.
Shrub and tree placement: Limit shrubs and trees to small, well-spaced clusters to break up continuous vegetation.
Pruning: Remove “ladder fuels” by trimming the lower branches of trees up to 6–10 feet from the ground to prevent a ground fire from climbing into the tree canopy.
Propane tanks: Clear vegetation from beneath large, stationary propane tanks.

What to do:

Clear vegetation from under large stationary propane tanks.
Create fuel breaks with driveways, walkways/paths, patios, and decks.
Keep lawns and native grasses mowed to a height of four inches.
Remove ladder fuels (vegetation under trees) so a surface fire cannot reach the crowns. Prune trees up to six to ten feet from the ground; for shorter trees do not exceed 1/3 of the overall tree height.
Space trees to have a minimum of eighteen feet between crowns with the distance increasing with the percentage of slope.
Tree placement should be planned to ensure the mature canopy is no closer than ten feet to the edge of the structure.
Tree and shrubs in this zone should be limited to small clusters of a few each to break up the continuity of the vegetation across the landscape.

Extended Zone (30-100+ feet) – Zone 3

The third Home Ignition Zone is 30 feet from the house and may extend up to 200 feet away. This Extended Zone is the area where you can interrupt fire, reduce the size of the flames, and keep fire lower to the ground, to keep it from spreading as rapidly.

Clear debris from the ground and reduce dead plants, trees, and leaves.
Keep the area between large, mature coniferous trees clear of smaller trees. Leave at least 12 feet of space between tree canopies when the trees are 30-60 feet from the house, and at least 6 feet of space between tree canopies when trees are 60-100 feet from the house.
If there are any outbuildings in the Extended Zone, keep them clear of plants and vegetation.

This outermost zone aims to reduce the overall fuel load and interrupt a fire’s path, keeping flames smaller and closer to the ground.

Thinning: Reduce the density of vegetation and space out trees. The recommended spacing between tree canopies decreases as you move further away from the house.
Ground cover: Remove heavy accumulations of ground litter, such as dead leaves, pine needles, and fallen branches.
Outbuildings: Clear vegetation away from storage sheds and other detached structures.
Collaboration: Working with neighbors to manage vegetation across property lines can increase the effectiveness of the extended zone.

What to do:

30-100 feet, out to 200 feet. Landscaping – the goal here is not to eliminate fire but to interrupt fire’s path and keep flames smaller and on the ground.

Dispose of heavy accumulations of ground litter/debris.
Remove dead plant and tree material.
Remove small conifers growing between mature trees.
Remove vegetation adjacent to storage sheds or other outbuildings within this area.
Trees 30 to 60 feet from the home should have at least 12 feet between canopy tops.*
Trees 60 to 100 feet from the home should have at least 6 feet between the canopy tops.*

*The distances listed for crown spacing are suggested based on NFPA 1144. However, the crown spacing needed to reduce/prevent crown fire potential could be significantly greater due to slope, the species of trees involved and other site specific conditions. Check with your local forestry professional to get advice on what is appropriate for your property.