Anti-mould and anti-condensation paint: what they do

Anti-mould and anti-condensation paints help, but only in certain situations. They make it harder for mould to grow on the paint and can reduce droplets on the wall. They do not fix leaks or rising damp. Before using them, you must deal with the cause and prepare the wall properly.

What an anti-mould paint is

It is a paint with additives that make it harder for mould to grow on the paint film itself. It is usually recommended for bathrooms, kitchens and damp rooms.

What it can do:

help mould take longer to appear on the paint;
give a surface that is easier to clean, depending on the type of paint;
be a good choice in rooms with a lot of vapour, once the damp has been dealt with.

What it does not do:

it does not kill the mould already on the wall underneath;
it does not remove the damp coming from inside the wall;
it does not last forever. The additives wear out over time and with cleaning;
it does not replace ventilation.

What an anti-condensation paint is

These paints usually contain components that make the surface feel less cold to the touch or that help absorb some of the moisture and release it later. The idea is to reduce the droplets that form on the wall when there is vapour.

In practice, the effect is limited. If a wall is very cold and the room has a lot of vapour, condensation may continue. These paints help in mild cases. For more severe cases, you need to improve the ventilation, the heating or the insulation of the wall.

When it makes sense to use them

in bathrooms, once the ventilation has been sorted out;
in corners and ceilings with mild condensation;
on walls where mould appeared and was cleaned, and the cause has been dealt with;
in damp rooms, such as kitchens and utility rooms.

When it is not worth it

if the wall has rain leaking in or a pipe leak;
if there are salt deposits and damp rising from the ground;
if the old paint is blistering and peeling;
if you only want to cover a patch of mould without cleaning it.

In these cases, the paint does not solve it. First you need to repair the source of the water.

How to apply it for the best result

Fix the cause of the damp.
Clean the mould wearing gloves and a mask, and let it dry well.
Scrape off loose paint and repair cracks.
Apply the primer recommended by the paint manufacturer.
Paint in two coats, respecting the drying time between them.
Keep the window open while it dries and for the following days.

Tip: Read the packaging. Each paint states the recommended primer, the time between coats and the type of room it is meant for.

A practical example

In a bathroom with no window, in Lisbon, the ceiling gets mould every winter. Painting with anti-mould paint helps, but only if you also install an extractor fan or open the door after showering. Without ventilation, the vapour continues and the paint ends up stained.

In homes near the sea or in the Sintra area, where the air is damper, the same care applies. The paint is a support, not the solution.

In short, a paint made for damp conditions is a good final step, after dealing with the cause and preparing the wall. If you are unsure about the source of the problem, ask a professional to assess it before painting.