Resources · 5 min read
Black stains in a corner, a crumbling wall, a whitish powder (saltpetre): these are signs of damp. Painting over them solves nothing — here's the right approach.
Identify the cause
- Condensation (lack of ventilation, thermal bridges)
- Infiltration (roof, façade, faulty joints)
- Rising damp (ground moisture, saltpetre at the bottom of walls)
Treat before painting
Paint is only the final step. You first have to remove the source of damp, clean up and treat the mould, let it dry, then apply suitable products (anti-mould, anti-damp undercoat).
The right everyday habits
- Air several times a day, especially the kitchen and bathroom
- Don't block the ventilation grilles
- Heat the rooms regularly
When to call in a professional
If the stains come back, if the saltpetre persists or if large areas are affected, a proper diagnosis is needed. We assess the situation and propose a lasting treatment before repainting.
A painting project in Geneva?
Estimate your work online or request a free, no-obligation quote.
Frequently asked questions
Can you paint straight over mould?
No: you have to treat it and remove the cause, otherwise it reappears under the new paint.
Is saltpetre serious?
It signals rising damp that needs treating. Left as it is, it gradually damages the walls.