How to clean soot off walls and ceilings, and when not to try.

Soot looks like dirt, but it does not behave like dirt. San José’s fire department warns that it smears easily and can leave oily black stains. Grab a wet rag first, as most of us would, and you can turn a gray film into a dark streak.

The good news is that the order of the steps does most of the work. Here is that order, what to clean with, and how to tell when a job is too big to do yourself. Our sources are the Red Cross, public health agencies, fire departments and restoration companies, and we point out where they disagree.

First, what kind of soot job is this?

Who should stay out of the cleanup

Colorado’s health department says to avoid cleanup if you have heart or lung disease, including asthma, if you are an older adult, or if you are pregnant. Keep children and pets away as well. Stop and call your doctor if you get symptoms such as repeated coughing, wheezing, chest tightness, headaches or nausea.

Before you start

After a house fire, do these first. Do not go in until the fire department says it is safe. Photograph every room before you clean anything, and call your insurance company. Michigan’s fire guide says to coordinate with your insurer before contracting for any service, or it may refuse to pay. Our guide to what to throw away after smoke damage covers the photos and the list your claim will need.

Then get set up:

• Protect yourself. A well-fitted N95 or P-100 respirator, gloves, long sleeves and shoes. Surgical and cloth masks will not protect your lungs from the finest particles. Add safety goggles.
• Turn off the heating and cooling. This keeps soot out of your air ducts.
• Open windows and run fans, as San José advises. Colorado also suggests short sessions with frequent fresh air breaks.
• Protect the room. Move the furniture out if you can, and lay drop cloths or plastic sheeting to catch falling soot.
• Test a hidden spot. ATI Restoration says to try any cleaner somewhere it will not show.

What you will need: a HEPA vacuum, dry soot sponges (also called chemical or dry-cleaning sponges), mild dish soap, warm water, clean sponges or microfiber cloths, towels and a stepladder.

How to clean soot off walls, step by step

1. Vacuum the loose soot. Use a HEPA vacuum if you can. BELFOR warns that other vacuums can blow fine particles back into the air. San José says to skip attachments with brushes or rollers, which can grind soot in, and Sierra says to hold the nozzle about half an inch off the surface.
2. Wipe with a dry soot sponge. Use gentle downward strokes. ATI warns that pressing hard grinds soot into paint and drywall. When the sponge turns black, switch to a clean side or cut off the dirty part. Do not rinse it.
3. Wash what is left. Mix dish detergent with warm water and use a new sponge or microfiber cloth. Work in small sections and wring the sponge often, since it will blacken quickly. Keep it damp, not soaking. ATI says too much water can push soot into drywall and lead to mold.
4. Rinse straight away. The Red Cross says to rinse each area with clear water right after washing.
5. Dry it completely. Use a towel, then keep the windows open and the fans running. The Red Cross says not to repaint until the walls and ceilings are completely dry.
6. Finish up. Clean or replace the filters in your furnace, air conditioner and any air purifiers. Check and clean your vents as well, as Sierra advises.

Top down or bottom up?

The sources disagree. The Red Cross says to wash walls from the floor up to prevent streaking, and to do ceilings last. Portland Fire & Rescue says to work from the ceiling down, and ATI says top to bottom. What they share matters more: one small area at a time, and rinse right away. The dry steps are easier from the top down, since soot falls onto the part you have not cleaned yet.

Cleaning soot off a ceiling

1-800 Water Damage says ceilings often collect more residue because smoke and heat rise, and that ceiling paint is often flatter and more delicate than wall paint. Be especially gentle with texture, and use as little water as you can. Stains that will not move may need sealing and repainting, not more washing.

Do not clean a sagging ceiling at all. The Red Cross says sagging means it got wet, which makes it heavy and dangerous. Stay out from under it and have it checked.

What is the best cleaner for soot?

There is no single winner, so start with the gentlest one that works.

Never mix ammonia with bleach. On Dawn: it is a dish soap, and dish soap is what these sources name for the washing step. We found no reliable source recommending WD-40 for painted walls, so we would not use it.

If the stain will not come off

Stop scrubbing. 1-800 Water Damage says repeated scrubbing can wear down paint or texture without fixing a deeper stain. The next step is usually a smoke sealer or stain-blocking primer, then paint.

Is your home older than 1978? The EPA says about three-quarters of U.S. homes built before then still contain some lead-based paint, and any renovation, repair or painting project can easily create dangerous lead dust. Think twice before scraping or sanding. The EPA recommends hiring a lead-safe certified contractor, and anyone you pay to disturb that paint must be certified. If you do it yourself, use lead-safe work practices. The National Lead Information Center is at 1-800-424-5323.

Is it really soot?

Soot or mold

The two can look alike. Servpro’s test is to look at where the marks are. Near an outlet, candle, fireplace or heating vent, or along the bottom of a door, they are more likely soot. Mold grows where there is moisture, such as between shower tiles or on a bathroom wall. If you are not sure, see our guide to how mold grows after water damage before you scrub.

Soot or char

Soot is a residue that smoke leaves on a surface. Char is the material itself, burned by fire or intense heat. No sponge fixes that. 1-800 Water Damage says drywall that is charred, warped, deeply stained or affected by firefighting water may need repair or replacement. The Red Cross adds that drywall and insulation soaked by fire hoses cannot be dried out and keep their strength.

If you can see blistered, cracked or burned material, leave that area alone and have it looked at. The U.S. Fire Administration warns that floors and walls may not be as safe as they look.

Is soot dangerous?

It deserves respect. The National Cancer Institute says soot may contain carcinogens including arsenic, cadmium and chromium, and that people can be exposed by breathing it, swallowing it or through the skin. The National Toxicology Program lists soots as known human carcinogens.

That needs some context. The human evidence those agencies describe comes largely from chimney sweeps, who worked around soot for years. It does not tell you the risk from one afternoon of cleaning. It is a good reason to wear protection and keep the job small.

The nearer-term concern is what is in the air. Colorado’s health department says smoke, ash and soot can leave particles and chemicals such as benzene on walls, floors and furniture. Those chemicals keep being released over the following weeks, and reduce over time. It recommends:

• Airing the house out when you can.
• Running air cleaners with HEPA and activated carbon filters until the smell goes away.
• Using a MERV 11 or higher furnace filter if your system can take one.
• Avoiding dry sweeping and dusting, which stir particles up.
• Not using ozone generators in occupied homes, because ozone is toxic to breathe.

That page seems aimed mainly at homes hit by smoke and ash from a nearby fire, not a fire inside the house, but it does cover cleaning soot and ash inside buildings. For health questions, talk to your doctor.

How to clean candle soot off walls

This is the easy version. Servpro says to open a window, wear gloves and goggles, cover the furniture, and start with a dry soot sponge. For a small smudge, a cloth dampened with rubbing alcohol is often enough. Test it somewhere hidden first.

To stop it coming back, Servpro says to trim the wick before burning and keep candles out of drafts. Keep them away from anything flammable, and never leave one burning unattended.

When to stop and call a professional

Sierra and 1-800 Water Damage list much the same signs:

• The stain comes back soon after cleaning.
• The smell stays. See our guide to getting rid of smoke smell after a fire.
• Paint is peeling or the drywall is damaged.
• Soot covers several rooms, large areas or the ceilings.
• The film is oily or heavy.
• Soot has reached the heating and cooling system.
• Materials were soaked by firefighting water.

A restoration crew starts with an inspection and a small test area, then removes dry soot before using any liquid and chooses a method for each surface. On a bigger job, BELFOR says crews use HEPA vacuums and air scrubbers to catch fine particles. If you had a house fire, ask your insurer whether the cleaning is covered before you spend your weekend on it. In Grand Rapids, our fire damage page covers what to expect locally.

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