Soot isn't just dirt
Smoke is a mix of gases and fine particles, and what's left behind depends on what burned and how. Wood and paper burning hot and fast leave a dry, powdery soot. Plastics, foam and rubber smoldering at lower heat leave a sticky, smeary residue that's much harder to clean. Kitchen fires that burn food leave a nearly invisible protein residue that discolors paint and holds a strong odor. A furnace malfunction can blow oily soot through the whole house. Each needs a different cleaning approach, so the first step is identifying what you're dealing with.
Soot residue can also be corrosive. Left on metal, stone, grout, appliances and electronics, it can etch and stain surfaces, and damp conditions make that worse. That's one reason cleaning is time-sensitive.
Don't wipe it yourself
It's natural to grab a sponge. On dry soot, wiping with a wet cloth often smears residue deeper into paint and textured surfaces, making the job harder. Don't run the heating or air conditioning either until the system has been checked: it can pull soot into the ducts and spread it to rooms the smoke never reached.
How the cleaning is done
- HEPA vacuuming. Loose soot is vacuumed with equipment fitted with high-efficiency particulate filters, so the fine particles are captured instead of blown around.
- Dry cleaning sponges. Chemically treated dry sponges lift dry soot from walls and ceilings before any liquid touches them.
- Wet cleaning. Degreasing cleaners matched to the residue are used on surfaces that can take it. Wet and protein residues usually need this.
- Air filtration. Air scrubbers with HEPA filters run while the work goes on, capturing particles stirred up by cleaning and demolition.
- Duct cleaning. If the heating and cooling system ran during or after the fire, the ducts and air handler usually need cleaning, and filters need replacing.
Odor: remove the source first
Smoke odor comes from residue, and residue hides in places you can't see: inside wall cavities, in insulation, on the back of trim, in carpet pad and in the ducts. No spray, fogger or machine can permanently remove odor while the residue is still there. The reliable order is to remove badly damaged materials, clean what remains, and only then treat the odor that's left.
Treatments that come after cleaning include:
- Sealing. Cleaned framing and surfaces that will be covered up are coated with an odor-blocking primer, so any remaining odor stays locked in.
- Thermal fogging. A deodorizer is heated into a fine fog that reaches the same places smoke did.
- Hydroxyl generators. Machines that break down odor molecules and can run while people are nearby.
- Ozone. Ozone generators can break down odors, but ozone is a lung irritant, so they're used only in unoccupied buildings, with people, pets and plants kept out until it clears. Ask how the company plans to use it and when the building will be safe.
Testing the result
A trained nose is still the main test of odor, but ask how the company will decide the work is finished. A good company walks the building with you after treatment, room by room, before walls are closed or painted.
Questions to ask
- What kind of residue is this, and how will you clean each surface?
- Which materials will you remove rather than clean, and why?
- Will you clean the ducts and the heating and cooling system?
- Which odor treatments will you use, and is the building safe to enter while they run?
- Will you seal framing before walls are closed?
- How will we decide together that the odor is gone?