Wall problems
Efflorescence (salitre) on walls
White powder that reappears, paint bubbling low on the wall, plaster crumbling. It is salt carried by moisture, and a coat of paint won't get rid of it.
Get quotesHow to recognise it
- White powder or crust, sometimes fluffy like cotton, that returns after cleaning.
- Concentrated low down, up to about a metre from the floor, or in basements and on façades.
- Blistered paint and crumbling plaster.
- A band of damp with a tide mark.
Where it comes from
- Rising damp from the ground, common in old houses, ground floors and basements.
- Water getting in through the façade or terrace.
- Salts in brick, plaster and cement, dissolved by the water and left on the surface as it dries.
What the painter does
Brush it off dry
No water, so no more salt is dissolved and carried back into the wall.
Remove what is damaged
Blistered paint and crumbling plaster.
Anti-salt treatment
Applied and left to work.
Re-plaster
Where needed, with plaster made for damp walls.
Breathable paint
For example silicate or lime paint, not paint that seals the wall and traps moisture.
What it adds to the job
- Much more time than painting alone: new plaster has to dry before it is painted, which can take days or weeks.
- It may need two trades: one for the damp and one for the painting.
- On the quote, look for: anti-salt treatment, plaster repair (with the area) and the type of paint.
- Ask what happens if the salt comes back.
Photos that help the painter
One close up of the white powder and one of the whole wall from the floor, to show how high it goes.
Frequently asked questions
Does washing it off work?
No: water dissolves the salt and carries it back into the wall, and it comes out again as it dries. Brush it off dry.
Why won't the paint hold?
The salt crystallises under the paint and pushes it off. Paint that seals the wall traps the moisture and makes it worse. Once the cause is dealt with, use paint that lets the wall breathe.
Get quotes with this problem already noted
The request opens with "Damp / mould" chosen as the wall condition and a note for the painters. You can change anything.
Get quotesOther wall problems
- Mould and dampBlack spots in corners and on ceilings that come back every winter.
- CracksFine lines in the plaster, cracks running from doors and windows.
- Peeling paintFlakes, blisters and paint that comes off with tape.
- Smoke stainsCeilings yellowed by smoking, walls darkened above the cooker or fireplace.