Preparation & Problems
Wall Preparation Before Painting in Kenya
What a wall needs before painting in Kenya: dry, sound and clean surfaces, damp and cracks to resolve first, peeling and chalky paint, and when skimming is a choice.
- Evidence reviewed
- October 2026
- Surface methodology
- FGS-1
Most painting problems start before the paint goes on. Paint applied to a damp wall, over loose old paint or onto a powdery surface can peel or fail early, however good the paint is. Preparation decides how long the finish lasts.
This guide explains what a wall needs before painting, in the order FinishGrid checks it, and where to go next for your own walls.
Check your own wall
Answer a few questions about one area and FinishGrid will show what it may need before painting. It's a guide, not a diagnosis.
First: moisture and cracks
Two things come before any painting decision, because paint can't fix either of them.
- Damp or a leak. Painting over damp doesn't fix it, and paint applied over moisture tends to fail early. Find and fix the source, let the wall dry, then prepare it. See Damp Walls Before Painting: What to Do First.
- Cracks whose cause is unknown or concerning. Have them assessed before decorating. Filling and painting over a crack hides it; it doesn't fix what caused it. FinishGrid doesn't judge cracks by width, because there is no Kenyan evidence for a safe threshold.
Cracks that a professional has already judged cosmetic can be opened, cleaned and filled as part of ordinary preparation.
Dry, sound and clean
Kenyan paint manufacturers' technical guidance is consistent: whatever the wall, before finishing it should be
- dry: no moisture held in the plaster or coming from behind it;
- sound: nothing loose, flaking or powdery left on the surface;
- clean: free of dust and dirt, with any shine dulled by light sanding so new paint can grip.
If you're unsure whether a new paint suits the existing coating, test a small patch first.
New plaster or previously painted?
The rest of the preparation depends on what the wall is now.
New plaster
- Make sure it is dry
- Smooth or rough?
- If rough: skim for a smooth finish, or paint the texture directly
- Preparation coat and finish coats
Previously painted
- Remove anything loose or flaking
- Sound, or chalky and powdery?
- Fill local defects
- Clean, dull the shine, repaint
Smooth or rough: is skimming needed?
Skimming covers a wall with a thin layer of filler to make it smooth. Kenyan technical data shows that unskimmed wood-float plaster can be painted directly; it simply uses more paint. So the real question is the finish you want:
- A smooth finish on rough plaster: skim first, then paint the skimmed wall like smooth new plaster.
- The plaster's texture is acceptable: paint it directly.
Skimming fillers sold in Kenya include cement-based and gypsum products, and they behave differently, so follow the product's own guidance. For filler quantities and what skimming costs, see Wall Skimming Cost in Kenya.
Peeling and chalky surfaces
Peeling or flaking paint is a symptom with several possible causes, so it isn't a preparation method on its own. Rule out moisture first, then remove all loose paint back to a sound edge and look at what remains. See Why Is My Paint Peeling?.
Chalky or powdery surfaces, often old cement paint, distemper or limewash, need the loose material removed and a penetrating primer to bind the surface before emulsion. Emulsion applied straight onto such a surface tends to lose adhesion. FinishGrid doesn't yet calculate paint quantity or cost for this kind of area.
Different areas, different needs
One house can have sound walls, a few damaged patches, a damp corner and new plaster in an extension. FinishGrid treats each area separately rather than labelling the whole house.
- Areas that are ready can be planned and calculated.
- Areas on hold (damp, a crack being assessed, plaster still drying) are left out until they're resolved.
- If one cause could affect several areas, such as a roof leak above several rooms, hold all of them.
- Work may still need to wait: a room is often repainted in one go, so one held wall can hold up the room.
Who to involve
The right first person depends on the cause, not the symptom. A painter is the right first call once moisture and structure have been ruled out.
| Situation | Appropriate expertise |
|---|---|
| Damp near bathrooms, kitchens or pipe runs | A plumber, to find and repair any leak first |
| Damp near the bottom of ground-floor walls | A damp-proofing or waterproofing specialist, or a building professional |
| Water from a roof, terrace or external wall | A roofing or waterproofing specialist |
| Cracks that may be structural | A building professional, such as a structural engineer or architect |
| Not sure what is causing it | A professional assessment before anything is quoted |
| Sound walls, local defects, chalky surfaces, skimming, new plaster once dry | A competent painter or painting contractor |
Planning quantities and cost
Once you know which pathway an area is on, you can plan it. The Paint Calculator works out how much paint to buy, and the Project Estimator gives a planning budget for the work. Neither calculates areas that are on hold or chalky surfaces.
Frequently asked questions
Can I paint straight over a wall that was painted before?
Often, if the old paint is sound: clean it, dull any shine and repaint. Loose, flaking or powdery paint needs more preparation first, and damp needs fixing before anything else.
Does every new wall need skimming?
No. Skimming gives rough plaster a smooth finish. If the texture is acceptable, the plaster can be painted directly.
Will anti-damp paint let me paint over a damp wall?
No. Anti-damp coatings are not a substitute for fixing the moisture source.
How FinishGrid built this guide
This guide follows the FinishGrid Surface Methodology v1 (FGS-1), the same rules behind Check My Wall. Its firm rules come from Kenyan paint manufacturers' technical information. Guidance from outside Kenya is used only as qualified context, never as a universal rule. It is general guidance, not a diagnosis of your wall.