How to Clean Soot Off Walls (and When Not To)

Short answer

Vacuum loose soot with a brush attachment, then wipe walls with a dry chemical soot sponge in straight strokes before using any water. Only after dry cleaning, wash with a degreasing cleaner and rinse. Wet or greasy soot, large areas and smoke odor are best left to a smoke damage professional.

Room with soot-blackened walls and furniture covered in ash after a fire

Before you start

Ventilate the room and wear gloves, eye protection and an N95 or better mask.
Cover floors and furniture with drop cloths.
Test on a small area first. If soot smears into a gray streak, stop; you'll spread it deeper into the paint.

Painted walls and ceilings

Vacuum loose soot with a HEPA vacuum and a soft brush attachment, without pressing into the wall.
Wipe with a dry chemical soot sponge in straight, overlapping strokes. Don't scrub in circles. Cut to a clean face or replace the sponge as it blackens.
Wash with a degreasing cleaner or a trisodium phosphate (TSP) substitute, working from the bottom up to avoid streaks, then rinse with clean water.
Let it dry fully. If stains or odor remain, seal with an odor-blocking primer before repainting.

Brick and fireplaces

Brush off loose soot, then scrub with a stiff nylon brush and a degreasing cleaner or a paste of baking soda and water, and rinse. Avoid wire brushes on soft or old brick, and don't use acid cleaners without testing a hidden spot.

When to call a professional

Call a crew when soot covers more than one room, is oily or sticky (from burning plastic or food), is on electronics or HVAC vents, or when smoke odor keeps coming back. See smoke and soot cleanup.

Questions

What is soot?

Soot is fine black or brown particles of unburned carbon, along with acids and other chemicals, left when materials burn incompletely. It's acidic and can stain and corrode surfaces if it isn't cleaned promptly.

Can I use water to clean soot off walls?

Not first. Water on dry soot often smears it into the paint. Remove as much as possible with a vacuum and dry soot sponge, then wash.

This guide is general information, not professional, legal or insurance advice. Follow your insurer's instructions and local codes, and put safety first.