Paint bubbles when the coating loses adhesion and pressure or movement lifts it from the surface. Common causes include moisture moving through the wall, painting a damp or hot surface, coating contamination, incompatible layers, or weak preparation. Open a small failed area only after checking for lead or other hazardous old coatings, then identify what is beneath the bubble and correct the cause before repainting.
This guide is written for South Africa, Australia, New Zealand. Always check local codes, product specifications, licences, and site conditions.
Read what the blister is telling you
The layer that separated is an important clue. Do not assume every bubble needs the same primer or repair.
Damp beneath the paint
The wall feels cool or damp, staining returns, salts are visible, or the failure worsens after rain, plumbing use or humid weather.
Next checkTrace and correct the moisture source, then allow the wall to dry appropriately.
Paint lifts to bare wall
The underside of the blister carries several paint layers and exposes plaster, masonry, timber or board.
Next checkCheck surface preparation, porosity, moisture and whether the first coat was suitable.
Only the top coat lifts
A sound older coating remains beneath the bubble.
Next checkInvestigate contamination, gloss, incompatibility or recoating before the lower coat had cured.
Sun-facing exterior bubbles
Failures are concentrated on hot elevations, dark colours or areas painted in direct sun.
Next checkCheck application temperature, trapped moisture and product limits before recoating.
Step by step
Check for an active moisture source
Compare the failure with rainfall, plumbing routes, wet rooms, ground level, window seals and condensation patterns. Repairing the coating before the water source will usually lead to recurrence.
Identify the failed layer
After completing any hazardous-coating checks, lift one loose edge and note whether separation is at the substrate, between paint coats or within a soft plaster layer.
Remove failure to a firm edge
Scrape only loose material, feather sound edges, clean contamination and repair weak substrate. Let repaired and moisture-affected areas reach the condition required by the coating system.
Prime and repaint as a system
Use a primer suited to the exposed material and failure mechanism, then apply compatible coats within the manufacturer's temperature, humidity, spread-rate and drying limits.
Expert tips
- Do not puncture a large water-filled blister near electricity.
- A moisture-resistant topcoat is not a repair for water moving through a wall.
- Test suspect old coatings before sanding or scraping them.
Common questions
Can I pop paint bubbles and paint over them?+
No. Remove loose coating to a sound edge and correct the reason it lost adhesion. Painting only the visible bubble commonly fails again.
Why does paint bubble after heavy rain?+
Rain can enter through roofs, walls, openings or failed seals and push moisture through the coating. Trace the exterior entry path rather than treating the paint alone.
How long should a damp wall dry before painting?+
There is no safe universal number of days. Drying depends on the wall, moisture source, climate and coating; verify the substrate condition against the product specification.
Sources & further reading
We link to official building-code, government and public-health material where a technical or safety claim needs authoritative context. Local rules and adopted code editions can change.
- Sherwin-WilliamsBlistering: causes and preventionCoating-manufacturer guidance on moisture, heat and application-related blistering.↗
- Benjamin MoorePaint bubbling and blistering troubleshootingTechnical troubleshooting guidance emphasising correction of the underlying cause before repainting.↗
- Royal Institution of Chartered SurveyorsDamp and mould consumer guideIndependent surveyor guidance on tracing moisture sources and avoiding common misdiagnosis.↗
Stop if the work involves structural uncertainty, hazardous materials, heights, live services, gas, serious water damage, or regulated work. Local rules differ—use an appropriately licensed professional where required.