Wildfire Home Protection: The First Five Feet

Up to ninety percent.

That is the share of home and business ignitions that embers account for in a wildfire, according to the research the U.S. Fire Administration cites in its briefing on the subject. Not the flame front. The sparks that arrive ahead of it, carried, the same page notes, several miles downwind — in one documented case a quarter of a mile, into vegetation beside a business in Superior, Colorado.

Which rearranges the problem. Wildfire home protection is not really about whether a wall of flame reaches your street. It is about what a glowing splinter the size of a match head finds when it lands on your property at two in the morning.

Better news than it sounds. A flame front is not negotiable. An ember is: it needs something fine, dry and combustible to land in, and nearly all of what it needs sits within five feet of your walls, in your gutters, or under your deck.

So this page is about the house. Leaving has its own clock, and it lives in wildfire evacuation.

Embers, not a wall of flame

The mental picture almost everyone carries is a front of fire moving through trees toward a house. It happens. It is not how most houses are lost.

What arrives is a shower. Burning bark, pine needles, splinters and cones, lofted by the fire’s convection column and pushed downwind ahead of everything else. They land in the hundreds, on every property in a neighborhood at once — which is why a street can lose houses in a scattered pattern that makes no sense until you understand that the fire never reached it.

An ember is a weak ignition source. That is the whole opening. It cannot light a concrete path, a metal screen or a wet lawn. It lights fine, dry, loose material: needles in a gutter, bark mulch, a coir doormat, a cushion, the leaves under a deck. Give it none of those within reach of your walls and it goes out on its own.

The USFA’s briefing sorts the arrivals four ways, which is a good way to walk your own lot: embers land on the structure, enter it through an opening, land on the landscape, or land on nearby fuels — fences, sheds, woodpiles — that burn next to it.

The tool below runs that chain one link at a time. Set each link to the state your house is in, then release an ember.

Ember chain — release one and watch

How far into your house does a single ember get?

Set each link to the state your own house is in this week, then release the ember. It moves inward one link at a time and stops at the first thing that refuses it.

open The extended zone 30–100 ft brush, dead wood, an unbroken canopy open The intermediate zone 5–30 ft shrubs under trees, limbs over the roof, firewood by the door open The first five feet 0–5 ft bark mulch, a shrub on the wall, a wood fence into the siding open Under the deck the underside open underneath, leaves and things stored open The deck boards the surface doormat, cushions, planters, a broom in the corner open Gutters, eaves and valleys the edge needles and leaves packed in open The roof itself the covering shingles loose or missing, debris in the valleys open Vents and soffits the opening unscreened, or screened at a quarter inch

Release an ember Set every link back to open

Run it twice: once honestly, once with the two cheapest links closed. The difference is what a Saturday buys.

Wildfire home protection begins in the first five feet

This is the part that surprises people who have spent years thinking about the tree line.

The Department of Energy’s building guidance describes an immediate zone made of the house and the area within a five-foot perimeter around it, and asks for that strip to be noncombustible: vegetation removed, ground cover of rock, stone, gravel or pavers, no woodpiles, no wood mulch, no dead plants or dried leaves. No branches extend into it either.

Five feet. Not fifty.

The reasoning is mechanical rather than cautious. An ember in bark mulch against your foundation is an ignition eighteen inches from your siding, with the wall as a reflector and the eave above as a chimney. An ember that lands on gravel is an ember on gravel.

Three things live in that strip in most American yards, and all three have to go. Bark or wood-chip mulch, replaced with stone or gravel ground cover^aff. — the Park Service warns off flammable mulches near structures for exactly this reason. Foundation plantings, especially junipers and anything resinous. And whatever has accumulated against the wall because the wall was convenient: the recycling, the spare lumber, the folded tarp, the firewood.

The fourth thing does more damage than any of them: a wooden fence that runs into the siding. It is a fuse with one end at the property line and the other at your house. The USFA’s own mitigation example is five feet of metal or stone where the fence meets the building.

Put gravel in the strip, keep the plants beyond it, and you have done the highest-return thing on this page.

Five to thirty feet, and thirty to one hundred

Past the immediate zone the goal changes. You are making sure that if the ground around you burns, it burns low, slow and separately.

The intermediate zone runs from 5 to 30 feet. The Department of Energy guidance asks for noncombustible landscaping and for vegetation selected and spaced to reduce risk: tree canopies at least 10 feet from the structure and at least 18 feet apart, ladder fuels removed — the shrubs and low branches that carry a ground fire up into a crown — and trees pruned from the ground up, six to ten feet.

The extended zone runs from 30 to 100 feet, and this is where people over-read the instruction and clear-cut their own property. The goal there is not to eliminate fire. It is to interrupt its path and keep flames smaller and on the ground. Spacing widens with distance: canopies at least 12 feet apart from 30 to 60 feet out, at least 6 feet apart from 60 to 100.

Ready.gov’s version is shorter and is the floor to work from: a zone free of leaves, debris or flammable materials for at least 30 feet from the home.

Two notes the diagrams never include.

Most suburban lots are not 200 feet wide. Your extended zone crosses the fence at about the point it starts to matter, which means part of your defensible space belongs to a neighbor. That is a conversation, not a chainsaw.

Then the woodpile, the most common single mistake on a rural property. The Park Service asks for firewood stacked at least 15 feet from the house, and that is a minimum rather than a target: a woodpile is the most efficient ember trap ever invented, hundreds of square feet of dry split surface with air between every piece. A steel firewood rack with a cover^aff. at the far end of the yard fixes it permanently, which matters more than fixing it once — the pile creeps back toward the door every February.

From the same page: keep grass in the safety zone cut to about two inches, and know that clearance requirements vary from state to state and county to county.

The openings: vents, gutters and the space under the deck

This is where an ember stops being a landscaping problem and becomes a building problem.

Vents, at one-eighth of an inch

Vents are the entry the fire wants. Attic and foundation vents exist to move air, they are open by design, and a fire two streets away makes its own wind. The specification is one-eighth-inch metal mesh on all vents, and eaves enclosed with a horizontal soffit cover. A quarter-inch screen — what a great many houses already have — passes an ember. Fiberglass insect screen melts.

A roll of mesh, tin snips, an afternoon. It closes the route that puts fire straight onto attic insulation, in the part of the house nobody looks at until smoke comes out of it.

Gutters, twice a season

A gutter packed with needles is a trough of ignition material running the length of the roof, pressed against the fascia board. Ready.gov’s list has cleared gutters on it and the Park Service’s does too. Doing it twice a season is the job; doing it once and then screening with a stainless micro-mesh gutter guard^aff. is how you stop doing it in August at 104 degrees.

If the roof edge is high, a telescoping gutter tool worked from the ground^aff. handles most of a single-story house without anyone leaving the lawn — for many households the only version of this job that gets done every year.

The space under the deck

The one people forget, and the worst of the three. Shaded, full of leaves, invisible, and where households put whatever has nowhere else to go. An ember that rolls under there is already under the house. Screen the perimeter in metal mesh, sweep it out, store nothing under it. Nothing.

The roof and the siding: the decisions you make once

Everything above is maintenance. These two are purchases, made at replacement time rather than in a panic.

The roof is the largest ember-catching surface a house owns, and its covering decides what happens when a hundred of them land at once. Ready.gov’s instruction is to use fire-resistant materials to build, renovate or make repairs. The practical version: the class of roof covering matters, loose or missing shingles are gaps rather than cosmetic flaws, and debris sitting in the valleys turns a good roof into a bad one for free.

Siding follows the same logic one step lower. The DOE guidance asks for fire-resistant or noncombustible materials on roofs, siding and decks, and the vulnerable detail is always the bottom edge — the last few inches where the siding meets the ground, the strip a burning mulch bed works against. Decking is that argument again, on a horizontal surface that collects everything.

If you are replacing none of them this year, at least know which one is your weak link. A decision made in advance costs nothing and gets made correctly.

What comes off the deck in July

Every list of this kind ends with a sentence about “removing combustible materials.” Here is what that means on a real deck, in the month it matters.

The doormat, if it is coir or natural fiber. Seat cushions and the outdoor rug. Plastic and resin planters, and anything holding dry potting mix. The broom in the corner. Cardboard that came with a delivery and stayed. Kindling. The bag of charcoal. Citronella candles. The folded umbrella and its cover.

All of it holds a glowing ember long enough. None of it is worth the house.

The failure mode is not ignorance, it is friction: a deck gets cleared in May and is full again by July because there is nowhere for any of it to go. A weatherproof deck box^aff. solves a preparedness problem by solving a storage problem, which is usually how these get solved.

Then walk the rest of the structure: under the stairs, behind the AC unit, the gap between shed and fence where leaves pile up every autumn.

Smoke: the part that lasts after the fire has moved on

A fire you can see is a short event. Smoke from a fire two counties away can sit over a town for a week, and it is what most American households actually get.

The EPA’s guidance starts somewhere unglamorous: the most effective way to protect yourself during wildfires is to limit your time outdoors when there is smoke in the air. Reducing physical activity and running portable air cleaners indoors come next.

Why a cloth mask does nothing

On masks the agency is blunt. Do not rely on dust masks or bandanas for protection from smoke. A respirator has to be tested and approved by the National Institute for Occupational Safety and Health, with NIOSH and either N95 or P100 on the packaging; it has to fit over the nose and under the chin and seal tightly to the face; and the EPA warns specifically against a mask with one strap, or two straps that loop around the ears, because neither is designed to seal.

A cloth mask fails both tests: it does not filter fine smoke particles and it does not seal. A NIOSH-approved N95 respirator^aff. does both, at the right size and with nothing under the seal. Buy a box, in sizes that fit the faces in the house, in a quiet month — the week the sky turns orange is the week there are none.

The clean room, which costs almost nothing

The EPA’s clean room page takes ten minutes to act on.

Pick a room big enough for everyone and comfortable to spend time in — the agency’s example is a bedroom with an attached bathroom. Close its windows and doors, without doing anything that makes it hard to get out. Run a portable air cleaner sized for that room, continuously, on its highest setting — which makes the delivery rate against the room’s square footage the only number to compare, so a true-HEPA air purifier rated for that floor area^aff. rather than the biggest box on the shelf. If a purifier is out of reach, the same page gives the alternative: furnace filters attached to a box fan with tape, brackets or a bungee cord.

Then keep the room free of what makes particles indoors: no vaping, no gas or wood stove, no aerosols, no frying, no candles, and no vacuuming without a HEPA filter.

For the rest of the house, Ready.gov and the EPA agree: high-efficiency filters^aff. in the central air conditioning, set to recirculate rather than drawing outside air in. On a window unit with a fresh-air option, close the intake.

The board below sorts what you plan to do into the part that works and the part that is doing nothing. Most households find two lines in the second column.

Smoke day — what is working and what is not

Tick what you plan to do. Some of it is doing nothing.

Every action here has conditions, and two of them have another action as a condition. Tick an action and its conditions appear underneath.

Tie a bandana or a cloth mask on before going out

Wear an N95 outside

The packaging says NIOSH, and N95 or P100 Two straps that go behind the head, not ear loops It covers nose and chin and seals against bare skin

Keep every window and outside door shut, day and night

Nothing is drawing outside air in — no whole-house fan, no window unit on fresh air

Run the central air

A high-efficiency filter is in it It is set to recirculate and the fresh-air intake is closed

Spend the smoke days in one room picked in advance

It is a room the whole household can actually sit in all day Nobody cooks, fries, vapes, vacuums or burns a candle in it

Run a portable air cleaner

It is the right size for the room it stands in It runs continuously, on its highest setting

Tape furnace filters to a box fan instead

They are furnace filters, held on with tape, brackets or a bungee

Open the house up at night to cool it down

Sweep or vacuum the ash off the porch and the floors

The vacuum has a HEPA filter A sealed respirator is on my face while I do it

Knowing when to bother is free. The Air Quality Index runs in six bands: 101 to 150 is where sensitive groups begin to feel it, 151 to 200 reaches some of the general public, 201 to 300 is a health alert for everyone, and 301 and above is a warning of emergency conditions.

If smoke arrives while the power is out — common when a utility de-energizes lines in high wind — the clean room and the air cleaner disappear at the wrong moment. That case runs on the logic of an extended power outage, and it argues for a way to hear official instructions that does not need the grid, compared in emergency weather radio. In summer it also collides with the heat: getting through a heat wave without AC works by opening the house at night, the one thing you cannot do in smoke.

What does not help, including things that sell well

The exterior sprinkler kit first. It depends on water pressure, on a pump, and on someone being home to start it — and the water system in a fire area is often depressurized by demand at the hour it is wanted. Away, it is a gamble. Home while embers fall, you should be in a car.

Gels and foams sprayed on siding are that problem one layer worse. They get applied in the window where you should be leaving, and the decision to stay and apply them is the decision that kills people. Ready.gov’s instruction when authorities say to go is to evacuate immediately.

The “fire-resistant plant list” gets more attention than it deserves too. Plant choice matters, but dry is dry: a fire-resistant species nobody has watered or pruned burns like anything else. Distance beats botany.

Then the pre-assembled “wildfire kit” in a bucket, which contains a dust mask — the section above explains why that is the wrong object. The correct spend is unglamorous: a roll of metal mesh, a box of respirators, a gutter tool, a Saturday.

One more, and it is the one I would argue about: the idea that any of this substitutes for an evacuation plan. It does not. The work on this page raises the odds that a house survives an ember shower with nobody in it. That is its whole claim. The plan for the people, the animals and the paperwork lives in the go bag guide and in important documents in an emergency, and that is the one that saves what cannot be rebuilt.

The one question this leaves you with

Walk the five feet around your house this week with a bucket, and count what you take out of it.

That number is the honest measure of where you stand — not the acreage of your lot, not the class of your roof, not how much you have read about defensible space. If the bucket comes back full, you have just found the most valuable hour of your season, and the rest can wait for winter.

The wider ranking of what threatens your particular address sits in natural disaster preparedness, and the supplies that carry a household through the days afterwards are counted out in the 72-hour emergency kit. If you want to know who writes this and why, that page is short.