Does anti-damp paint fix a damp problem?
No. It helps in some cases, but it does not fix damp. The paint holds back surface mould for a while, and the cause is still there.
What the paint does
Anti-damp or anti-mould paints usually contain additives that make it harder for mould to grow on the paint film, and some cope better with damp rooms such as bathrooms. That can be useful as a finishing coat, once the cause has been resolved.
Be wary of packaging promises too. Phrases such as "stops damp" or "waterproofs the wall" describe how the paint film behaves, not the whole wall, and they depend on the surface being dry, clean and free of an active cause. Always read the manufacturer's instructions and, if the label seems to promise more than a paint can deliver, take that as a sign to look for the source of the water first.
What the paint does not do
It does not stop water getting in, does not repair a pipe or a façade, and does not dry a wall that is damp inside. If the water comes from inside the wall, through ingress or a leak, the stain comes back and the paint blisters.
In practice the result is much the same as painting over the stain: for a while the wall looks fine, then the mould returns, the paint bubbles and you end up paying twice, for the paint and for the repair.
When it can help
- In rooms with mild condensation, as a finish after improving ventilation.
- As a final coat, after repairing the cause and letting the wall dry.
- In bathrooms and kitchens, where vapour is frequent, as a complement to ventilation.
When it will not solve it
- When there is water ingress from the roof, façade or a window.
- When there is a leak in a pipe.
- When the wall is wet to the touch or the earlier paint has already blistered.
- When the mould returns in the same place, a sign the cause is still there.
What to do now
- Find the cause. Photograph the stain, see when it grows and whether it worsens with rain or cold.
- Repair the cause. Fix the ingress, the leak or the ventilation, and let the wall dry.
- Choose the paint afterwards. With a dry wall, a suitable paint can be a good finish.
Cause first. Paint after.
If you are in a rented flat, check with your landlord (senhorio) before repainting, and keep the photos of the stain from before.
When to call a professional
Get help if the stain came back after painting, if the paint is blistering or peeling, or if the wall is wet. Look for a plumber (canalizador), a builder (pedreiro) or a roofer (telhador) depending on where the water comes from, and a painter (pintor) for the finish once the cause is resolved.
Frequently asked questions
Does anti-damp paint stop mould?
It makes mould harder on the paint surface but does not remove the moisture feeding it. If the cause persists, the mould can return.
Can I apply it on a damp wall?
It is not advisable. A damp wall should dry before it is painted, and the cause should be resolved.
Is it better than ordinary paint?
In damp rooms it can be a good choice of finish. It does not replace repairing the cause.
Does Cuidasa recommend a paint?
No. It can suggest the likely cause from photos, so you know what to fix before painting. It does not replace an inspection by a professional.
Related
Still unsure?
A stain that keeps coming back? Photograph it and Cuidasa suggests the likely cause. Join the waitlist on the Cuidasa homepage.
Join the waitlistInformational content only. The causes mentioned are likely, not certain, and do not replace an inspection by a qualified professional.