Cracked Paint from Moisture

Paint that cracks, bubbles, blisters or flakes away is often written off as poor decorating. Sometimes that is the case, but when it keeps happening in the same area, or appears alongside staining or a musty smell, moisture in the wall is the usual explanation.

Why moisture damages paint

Water moving through masonry and plaster carries dissolved salts with it. When the water reaches the surface and evaporates, the salts crystallise behind the paint film and push it away from the wall. Moisture vapour trying to escape through a non-breathable paint can also form blisters. The result is the familiar bubbling and powdery, flaking surface.

Where it appears tells you a lot

• Low on the wall, with a tide mark: possible rising damp or a bridged damp proof course.

• High on external walls or around windows, worse after rain: likely penetrating damp from pointing, render, gutter or window defects.

• On chimney breasts: rain entry through the stack or salts in the old flue.

• On cold corners and ceilings with mould spots: condensation.

Why repainting doesn't solve it

Painting over the damage only hides it for a while. As long as moisture and salts are still moving through the wall, the new coat will fail in the same way – sometimes faster, if a less breathable paint has been used. In older solid-walled properties, modern plastic-based paints and gypsum plasters can make things worse by trapping moisture that would otherwise evaporate.

Fixing it properly

The cause of the moisture needs to be identified and dealt with first, whether that is an external repair, improved ventilation or damp proofing. Salt-contaminated plaster is often removed and replaced with a suitable replacement plaster. The wall should then be given time to dry out before redecorating, using a breathable finish where appropriate.

We can carry out the treatment and the replastering and redecoration afterwards, so you are not left with bare walls once the damp work is complete.

Related help

If this sounds like your home, our damp and mould surveys service explains how we diagnose and treat it in practice. You may also find Damp Patches on an Interior Wall and Signs You Need Damp Proofing useful.