Fix bubbling or blistering paint

Scrape back bubbling paint, find and fix the damp or heat causing it, then reprime and repaint properly.

BP-01Set up your work areaMove furniture clear of the wall and lay dust sheets on the floor. Open a window for ventilation, since scraping old paint creates dust. Wear a dust mask and gloves before you start.

1 each · Dust sheet

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1 pack · Disposable dust mask (FFP2)

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1 pack · Disposable gloves

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BP-02Work out what caused the bubblingBubbling paint usually means damp, heat, grease, or paint applied over a damp surface. Press gently on a bubble to see how it behaves, and check the wall type: on solid brick or block, look for damp patches or a white powdery residue (efflorescence), which points to rising or penetrating damp. On plasterboard, whether on timber or metal studs, a bubble that feels soft or springy can mean a leak behind the board, for example from a pipe near a bathroom or kitchen. On dot-and-dab plasterboard, bubbling near skirting or joints often means the adhesive dabs have failed because water got behind the board. On lath and plaster in a house built before the 1960s, treat the old paint layers as possibly containing lead.

RULES

1 each · Lead paint test kit

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KNOW THE RULES

If the property predates 1960 and has lath and plaster walls or ceilings, HSE guidance says to assume old paint layers may contain lead. Use a lead test kit if unsure, and avoid dry sanding — use wet scraping and a proper mask instead.

BP-03Scrape off the loose and bubbled paintUse a paint scraper to lift off all the bubbled, flaking, or peeling paint, working back to a firm, sound edge. Go slowly and don't force the scraper into the plaster or board underneath. If you suspect lead paint, keep the surface damp while you scrape to stop dust becoming airborne.

1 each · Paint scraper

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BP-04Sand the edges smoothSand the edges where old paint meets bare wall or plaster so there's no hard ridge. Wipe the area with a damp cloth to pick up dust before you carry on.

1 sheet · Medium-grit sandpaper (120 grit)

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1 each · Cloth

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BP-05Deal with the cause before you repaintIf damp caused the bubbling, fix the source first — improve ventilation, sort a leaking pipe, or address a damp-proofing issue — and let the wall dry out fully, which can take days or weeks depending on how wet it is. Repainting over a damp wall just makes the paint bubble again. If the damp keeps coming back after drying out, get a builder or damp specialist to check the wall, since it could point to a building defect rather than a simple painting job.

1 each · Damp meter

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BP-06Fill any dents or holesFill any gouges or holes left by scraping with a multi-purpose filler, pressing it in flush with a filling knife. Leave it to dry fully, then sand it smooth and level with the surrounding wall.

1 each · Multi-purpose filler (tub)

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1 each · Filling knife

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BP-07Prime the bare patchesApply a suitable primer to any bare plaster, plasterboard, or filler. If the bubbling left a watermark or a stain, use a stain-blocking primer so it doesn't bleed through the new paint. Let the primer dry fully before continuing.

1 each · Stain-blocking primer (250ml)

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BP-08Mist coat any bare plasterIf you've exposed fresh plaster on a solid brick or block wall, apply a mist coat first — ordinary emulsion diluted about 70% paint to 30% water. This stops new plaster soaking the topcoat unevenly. Skip this step if you're only priming plasterboard or filler patches.

1 litre · Emulsion paint (for diluting)

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BP-09Repaint the wall or ceilingApply two coats of matching emulsion, feathering each coat out into the surrounding paintwork so the repair doesn't show. Let each coat dry fully before the next, following the tin's drying time.

2.5 litre · Emulsion paint (matching colour)

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1 set · Paint roller and tray

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1 each · Paintbrush (for edges)

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BP-10Clean up and dispose of wasteWash rollers and brushes, and let the room ventilate while the paint cures. Bag up scraped paint and dust sheets for normal household waste. If you tested positive for lead paint, double-bag the scrapings and check your local council's guidance on disposal rather than putting them straight in the bin.

RULES

2 each · Bin bags (heavy duty)

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KNOW THE RULES

There's no single UK law banning DIY removal of lead paint, but HSE and most councils recommend double-bagging scrapings and checking local disposal guidance rather than putting them in general waste.

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