Quick answer: Paint peels, bubbles and grows mould when water gets into the wall, or when it was applied over dust, chalky paint or uncured plaster. The lasting fix is to find and stop the water source, let the wall dry, remove loose paint, treat mould, apply a sealer or anti-damp primer and then repaint with two coats of suitable paint.
Every year, after the long rains (March–May) and the short rains (October–December), many Kenyan homeowners find bubbling paint, white powder or black mould on their walls. Repainting straight over it rarely works. Here is how professional painters diagnose and fix it.
Common causes of damp and peeling paint
| What you see | Likely cause |
|---|---|
| Bubbling or peeling at the bottom of walls (up to about 1 m) | Rising damp: missing or failed damp-proof course, soil or paving piled against the wall |
| Damp patches under windows | Leaking window sills or frames, cracked render |
| Stains on ceilings and the tops of walls | Roof leaks, blocked gutters, leaking water tanks |
| Wet patches near bathrooms or kitchens | Plumbing leaks, failed grout or sealant |
| Black mould in corners and behind wardrobes | Condensation and poor ventilation |
| White powder or crystals (efflorescence) | Salts carried out of masonry as water evaporates |
| Peeling paint on dry walls | Painting over dust or chalky paint, no primer, or uncured plaster |
Step 1: Stop the water
No paint can hold back a constant water supply. Depending on the cause:
- Repair roof leaks, flashings and cracked ridge caps, and clear gutters and downpipes.
- Make sure the ground slopes away from the house and that rainwater from downpipes drains away from the walls.
- Lower soil, flower beds or paving that sit above the damp-proof course.
- Fix plumbing leaks and reseal showers, sinks and window sills.
- Fill cracks in external render so rain can’t penetrate.
- Improve ventilation in kitchens, bathrooms and bedrooms with mould.
Step 2: Let the wall dry
Walls can take weeks to dry after the source is fixed. Painting while they are still wet traps moisture. This is why we usually recommend investigating during the rains and repainting in the dry season.
Step 3: Prepare the surface properly
- Scrape off all loose, bubbling and flaking paint back to a firm edge.
- Brush off efflorescence (white salts) when dry. Do not wash it back into the wall.
- Wash mould with a fungicidal solution, leave it for the recommended time, then rinse.
- Rake out and fill cracks. Replace crumbling plaster.
- Sand edges smooth so the repairs don’t show through the new paint.
Step 4: Prime and repaint with the right products
- Anti-damp primer or sealer on walls that have had moisture problems.
- Alkali-resistant primer on new plaster repairs.
- Anti-mould paint in bathrooms, kitchens and rooms with condensation.
- Weatherproof exterior emulsion outside. Read our guide to the best paint for exterior walls in Kenya.
- Two full coats, at the manufacturer’s spread rate.
Peeling paint that isn’t caused by damp
Sometimes walls are dry but paint still peels. Common reasons:
- Painting new plaster too early: it needs to cure, typically about four weeks, before painting. See our guide to painting a new house.
- Painting over chalky or dusty paint without washing and sealing it.
- Watered-down paint that is too thin to bond.
- Emulsion over gloss without sanding or an undercoat.
When to call a professional
If damp keeps returning, covers a large area, or comes with cracks in the structure, get the building inspected. A professional painting company can identify surface causes, carry out the preparation and use the correct primers so the repaint lasts.
BrushMasters handles damp treatment, mould removal and repainting across Nairobi and Kenya. See our interior painting and exterior painting services, or book a free site visit. We’ll inspect the walls and explain the fix before quoting.
