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Most homes lost in wildfires are ignited by embers, not by the fire front. Embers travel ahead of a fire on the wind, land in gutters full of needles, on a wood deck, in a mulch bed against the siding, or blow into an attic vent, and the house burns from that small start. Defensible space is the practice of making sure nothing within reach of the house will carry that ember's fire to the wall, and home hardening is making the house itself resist ignition. FEMA and the NFPA describe both in zones, and the zones are the checklist.
This post is for owners in fire-prone regions, which now include a lot of the West, parts of the South, and suburban areas that never thought of themselves as wildland. It is a fall or spring project, done before the season, and it is mostly yard work.
What are the zones?
FEMA's guide to preparing for a wildfire describes the Home Ignition Zone from NFPA's Firewise program as extending up to 200 feet from a structure, in three zones. Within a minimum 30-foot defensible space: clear leaves, needles, and debris from the roof, gutters, decks, and around the foundation; remove vines from the house; move shrubs away from the walls; prune branches within 15 feet of chimneys and the structure; avoid bark and wood chip mulch next to any structure; remove tree limbs within 15 feet of the ground; and store cushions and other flammable items. From 30 to at least 100 feet: reduce flammable vegetation and create fuel breaks such as driveways, gravel walks, and lawns. From 100 to 200 feet: thin vegetation, keep tree canopies from touching, and stack firewood at least 100 feet from the house. Extend the zones on the downhill side of a slope. Ready.gov adds: use fire-resistant materials to build and repair, have an outdoor water source with a hose that reaches every part of the property, and keep a fire-resistant zone free of flammable material for at least 30 feet.
The NFPA and many state fire agencies now single out the first five feet as its own zone (the "immediate" or "ember-resistant" zone) and treat it as the most important: nothing combustible touching or under the house.
| Zone | Distance | Goal | The work |
|---|---|---|---|
| Immediate | 0 to 5 feet | Nothing that burns touches the house | Replace mulch with gravel or pavers; remove plants against the wall; nothing stored under decks or against siding; move the firewood, the propane tank, the trash cans; clean the roof and gutters |
| Intermediate | 5 to 30 feet | Fire cannot reach the house or climb into trees | Lawn or hardscape breaks between plant islands; shrubs spaced and away from trees; lower limbs pruned; dead material removed; irrigate what stays |
| Extended | 30 to 100 feet and beyond | Slow the fire, keep it on the ground | Thin brush and small trees; separate canopies; fuel breaks; firewood 100 feet out |
How do you harden the house itself?
Defensible space limits the fuel around the house; hardening makes the house resist the ember that lands anyway. FEMA's list for an existing house, in rough order of value: a Class A roof with clean gutters, fine metal mesh over every vent, enclosed eaves and decks, tempered or multi-pane windows, non-combustible siding and fence sections near the house, a spark arrestor on the chimney, a visible address with a clear driveway, and dual-sensor smoke alarms.
- Roof and gutters. A Class A roof (tile, slate, asphalt shingles with the right underlayment). Gutters kept clear of needles and leaves, or fitted with metal guards; the gutter guide is now a fire task as well as a water task.
- Vents. Attic, foundation, and eave vents covered with fine metal mesh (FEMA's guidance says fine wire mesh; many states specify a small mesh size or an ember-resistant vent product). Embers enter attics through ordinary vents. The attic check is when to look at them from inside.
- Eaves and the underside of decks. Enclosed or boxed so embers cannot lodge.
- Windows. Multi-pane or tempered glass; shutters for large windows facing vegetation.
- Siding and fences. Non-combustible siding where the house is close to neighbors or vegetation; a wood fence that touches the house is a fuse, so the last few feet should be metal or masonry.
- Chimney. A spark arrestor, and the chimney inspected.
- Access. The address clearly visible from the road, and the driveway wide and clear enough for a fire engine.
- Alarms. Dual-sensor smoke alarms, tested monthly; the detector guide covers the schedule.
What should you do when a fire is near?
FEMA's list for the minutes before evacuating, if there is time and only if there is time: turn on the lights inside and out so the house is visible in smoke; close every window, vent, door, and fireplace screen; disconnect the automatic garage door opener so the door can be opened by hand without power; move flammable furniture, including outdoor furniture, to the center of the house away from windows; remove flammable window coverings. Then leave when told to, with the five Ps: people, prescriptions, papers, personal needs, priceless items.
The papers are where the home record comes in. The insurance policy, the inventory with photos, and the equipment list are what a claim needs, and they need to exist somewhere other than the house. The storm post makes the same point for hurricanes; the digital copy is the version that survives.
What should you record?
The date the zones were cleared and what was done, photos of each side of the house from the same spots each year, the vent and gutter products installed, the roof class, and the evacuation plan. Set the zone maintenance as a yearly task before fire season, with the gutter cleaning and the roof and attic checks on the same day; in fire country they are the same job.
Common questions
How far does defensible space need to extend?
FEMA's guidance, following NFPA's Firewise program, describes a Home Ignition Zone of up to 200 feet, with the highest priority on the first 30 feet and the most restrictive treatment in the first five. On a slope, extend the zones downhill; fire moves faster uphill. Your local fire agency's rules for your area are the ones that apply.
What are the highest-value changes if I can only do a few?
Clear the first five feet of anything that burns (mulch, plants against the wall, stored items under the deck), clean the roof and gutters of needles and leaves, cover vents with fine metal mesh, and keep the address visible and the driveway clear. Those address embers, which cause most ignitions, and access, which decides whether a fire engine can help.
Does this apply if I do not live in the forest?
Ember-driven fires have burned suburban neighborhoods well inside city limits, house to house, with fences and mulch beds as the fuel path. If your area has a fire season and your house has vegetation or combustible materials against it, the first-five-feet rules apply regardless of what the lot backs onto.
What should you do next?
Walk the first five feet around the house this weekend with a rake and a trash can. Then check the local fire agency's defensible-space page for the rules in your county; many offer a free home assessment, which is the best next step.