When a veld fire runs across the mountain, the smoke doesn't stay on the slopes. The southeaster carries fine soot down into the surrounding suburbs, and by morning walls, windows and roofs across the neighbourhood are wearing a grey film with dark streaks running off the eaves. Grab a hosepipe or a rented machine and you'll likely smear it deeper. This is what soot actually is, why it needs a different approach, and how a proper clean can save you a full repaint.
Why ordinary washing makes it worse
Soot isn't ordinary dirt. It's the oily, carbon-rich residue of incomplete combustion, and it carries a slightly acidic edge from everything the fire consumed. That oiliness is the problem. Wipe it with a wet cloth or blast it with a pressure washer set too hard and you don't lift it off the wall, you grind it into the paint film and drive it into porous plaster where it sets like a stain.
The acidity matters too. Left sitting on paintwork and render, soot slowly etches the surface, and the longer it stays the harder it bonds. The real deadline is the first proper rain. Once a wet winter front rolls through, water pulls the oily residue deeper and locks it in. That's why we always tell people the same thing: the fresher the soot, the better the result.
Act fast, but act right
If your home was in the smoke path, the first few weeks are your best window. That doesn't mean rushing out with whatever's in the garage. A rented machine in the wrong hands strips paint, forces water behind cladding and turns a cleaning job into a repair job. The goal is to break the soot down chemically first, then rinse it away gently, not to power it off by brute force.
How we approach soot-stained walls
Every fire leaves a different mess depending on what burned and how the wind sat, so we don't treat two homes the same. The process runs in three stages:
- Dry assessment: before any water touches the wall, we look at how heavy the deposit is, what surfaces are affected, and where the soot has already started to stain versus where it's still sitting on top. This decides the products and the pressure.
- Pre-treatment: we apply a degreasing, soot-specific solution that breaks down the oily film and lifts it off the surface chemically. This is the step a hosepipe can't do, and it's what stops the smearing.
- Controlled low-pressure rinse: once the residue is broken down, a soft, low-pressure rinse carries it away without driving it into the plaster or stripping the paint. On delicate surfaces we drop the pressure right down and let the chemistry do the work.
Different surfaces, different handling
The wall material changes everything about how we treat it. What's safe on face brick would ruin a freshly painted wall.
- Painted plaster: the most vulnerable. Too much pressure lifts the paint and any soot ground into it stays as a shadow. This is soft-wash territory: strong pre-treatment, gentle rinse, patience.
- Face brick: tougher, but porous, so soot soaks into the pores and pointing. It handles more, yet still wants the right cleaner rather than raw pressure, or you open up the mortar joints.
- Natural stone: the fussiest of the three. Acids and harsh chemicals can etch or discolour it permanently, so it needs pH-appropriate products and a careful hand from someone who's cleaned it before.
Soot doesn't only land on walls. It settles just as heavily on roof sheeting and tiles, and streaks down from there every time it rains, so it's worth having the roof looked at in the same visit. Our roof cleaning service handles that, and both fall under our wider exterior cleaning work.
Insurance and saving the repaint
If the smoke damage is significant, it's worth phoning your insurer before anything gets cleaned. A quick set of dated photos and an assessment can support a claim, and some policies cover fire-related soot cleaning. We're happy to walk the property with you and give an honest read on what a clean will and won't fix. More often than not, catching it early means a thorough soot removal saves the wall, and that's a few hundred Rand against the cost of repainting the whole house.
Frequently asked questions
Can I just pressure wash soot off myself?
You can, but it's the fastest way to make it permanent. Without a degreasing pre-treatment the soot is oily, so a plain water blast smears it into the paint and forces it into porous plaster. On painted walls it also strips the paint. If it's a light dusting on face brick you might get away with it, but on painted or stone surfaces get it assessed first.
How quickly do I need to act after a fire?
Within the first few weeks, and ideally before the first proper rain. Fresh soot sits on the surface and lifts fairly easily. Once rain soaks it in, or it's baked on through a hot dry spell, it bonds far harder and the result is never quite as clean.
Will soot removal save me from repainting?
Very often, yes. If we get to it while it's still surface soot, a proper pre-treatment and soft rinse brings the wall back without a repaint. Once it's been ground in by DIY scrubbing or left through a wet winter, the staining can be permanent, which is exactly why acting early pays off.
Does soot damage the roof as well as the walls?
It does. Roofs catch the heaviest fallout and then bleed soot down the walls with every shower, so cleaning the walls alone is a half job. We usually check the roof and gutters in the same visit and treat it all together.
Been affected by smoke or soot? The sooner it's treated, the more we can save. See our exterior cleaning services, get a free assessment, or call us on 079 616 7761.