Peeling paint or blown plaster

Peeling Paint or Blown Plaster

Flaking, bubbling or crumbling finishes are a sign of trapped moisture behind the wall.

OxfordshireDamp · Remedy · Restore

Field note

Category: Wall symptoms
Likely cause: Rising Damp
Guarantee: 10-year written

CSRT-accredited survey

Schematic · Plate 04

AP/DAMP

Flaking, bubbling or crumbling finishes are a sign of trapped moisture behind the wall.

The cause

What causes it

When paint flakes off a wall in sheets, or plaster sounds hollow when tapped and crumbles to powder, the cause is almost always trapped moisture in the wall behind the finish. As damp tries to evaporate through the surface, it pushes paint film away from the substrate and breaks the bond between plaster and brick. The underlying water source is most often rising damp, but penetrating damp from a defective gutter, cracked render, or failing pointing can produce the same symptoms higher up the wall.

Presentation

What to look for

Look for paint that lifts in flakes rather than peeling cleanly, leaving a chalky residue underneath. Plaster may feel cold to the touch, sound drum-like when knocked, or shed a fine white powder onto the skirting. In bad cases whole sections of plaster bulge away from the wall and detach when pressed. The damage often follows a tide line — a clear horizontal boundary above which the wall is sound — which helps distinguish ground-source damp from a localised leak.

Why it matters

If it is left alone

Once plaster has blown, redecorating over it never lasts — the new paint will peel within weeks because the substrate behind it is unstable. Beyond cosmetics, blown plaster is a sign that the wall has been wet for a long time, which in older properties means the lime mortar joints, embedded floor timbers, and skirting boards are likely to be deteriorating too. Acting promptly limits the repair to plaster and decoration; waiting can pull joinery and structural timber into the scope.

The remedy

How we treat it

A proper survey establishes whether the source is rising damp, penetrating damp, or a hidden leak, since each requires a different fix. Where rising damp is the cause, we install a chemical damp-proof course and replace the failed plaster with a salt-resistant render that contains residual contamination. For penetrating damp, the external defect — pointing, render, gutter, or flashing — is repaired before any internal replastering, otherwise the new finish will fail again. The full specification is provided in writing and the work carries a 10-year guarantee.

Recommended treatment

Rising Damp Treatment

Every treatment begins with a CSRT-accredited on-site survey, is delivered to a written specification, and is backed by a 10-year guarantee against recurrence.

Written specification 10-year guarantee

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