Cleaning Wildfire Ash and Smoke Residue From Your Home's Exterior

The short answer: wet it, don't stir it

Wildfire ash is fine, light and easy to lift into the air. The worst thing you can do is grab a broom or a leaf blower. Instead, mist the surface lightly so the ash clumps and stays put, then wash it away with a gentle rinse or a low-pressure soft wash. Do this only after local officials say the air is safe and the fire threat has passed.

Most ash on walls, windows and patios comes off with water and a mild detergent. Smoke residue, the oily gray film that clings to stucco and trim, takes a cleaning solution and some dwell time. Neither one needs high pressure.

Why ash is different from ordinary dust

Regular dust is mostly soil. Ash from a wildfire can include burned plant material, and when homes or vehicles burned nearby, residue from building materials too. Public health agencies generally advise treating it with care for that reason, and they note that wet ash can irritate skin.

Ash particles are also very small. Dry sweeping, blowing or blasting with a hard spray sends them back into the air you breathe and onto surfaces you just cleaned. Water is your friend here, but only as a gentle mist first and a controlled rinse second.

Protect yourself before you start

Check your local air quality and any guidance from county public health before doing outdoor cleanup. Agencies commonly recommend a well-fitted N95 respirator rather than a cloth or paper mask, plus gloves, long sleeves, long pants and eye protection. Keep kids and pets inside while you work, and keep windows closed.

When you finish, take off your work clothes outside or right inside the door and wash them separately. Rinse your boots before walking through the house. If you have asthma, heart or lung problems, this is a job to hand off.

A gentle washing method that works

Start by misting the area with a hose on a soft shower setting. You want the ash damp, not running. For patios and walkways, scoop or squeegee heavy deposits into a bag rather than washing piles of ash into the yard or street.

On walls, work from the top down so dirty water never runs over a clean section. Apply a mild detergent or house-wash solution with low pressure, let it dwell a few minutes without drying in the sun, then rinse thoroughly from the top. Smoke film on stucco often needs a second pass. Windows come clean with ordinary glass-cleaning methods once the grit is rinsed off first, which keeps you from dragging abrasive ash across the glass.

Do not use a narrow, high-pressure tip on stucco or wood to speed things up. Ash is not stuck by force; it is stuck by film. Chemistry and time remove film. Pressure just drives grit into porous surfaces and can damage the finish.

Keep the runoff out of the storm drain

Ash-laden wash water should not flow down the driveway into the gutter. Los Angeles Municipal Code section 64.70.02 prohibits discharging untreated wash water from paved-surface washing and mobile operations into the storm drain system unless a permit allows it. Storm drains in LA carry water to creeks and the ocean without treatment.

In practice, that means using as little water as the job needs, blocking or berming the low edge of a driveway, collecting heavy ash dry before washing, and letting small amounts of rinse water soak into landscaped areas where it can. Our guide on where wash water goes covers the rules in more detail.

When to wait, and when to bring in help

Wait if the fire is still active anywhere nearby, if winds are still carrying smoke, or if officials have issued cleanup guidance for your area that you have not read yet. Ash keeps falling during a fire, and cleaning too early just means cleaning twice. In LA, fire season often overlaps with Santa Ana wind events, so give it a few calm days.

If your property was close to burned structures, follow official debris and hazardous-material guidance before any washing. That cleanup is a specialized process and is not a pressure washing job.

For homes that simply have ash and smoke film on walls, eaves, windows and hardscape, a professional low-pressure house wash is a reasonable next step. At Say Wash It we soft wash walls top down and contain rinse water on paved areas. House washing runs $0.35 per square foot of exterior wall as of October 2026, and you can check your number with the instant quote on this page. Be realistic about one thing: smoke can leave a faint tint on very porous, unpainted surfaces that lightens with cleaning but may not fully disappear.