How to remove mould from walls

on Oct 11, 2026

in Building Materials & DIY, DIY Guides & Building Tips

Black or grey spots in a corner of the bathroom, behind the cupboard or above the window: mould on the wall is a common problem, especially in autumn and winter. You can often remove small patches safely yourself. Even more important is finding out why the mould is there. If you do not deal with the cause, it keeps coming back. This blog explains step by step how to tackle it, what protection you need and when it is better to call in a professional.

👷 Calling in a professional is never superfluous. Is it a large area, is the mould in the plaster or behind wallpaper, does it keep coming back or are your airways affected? Have a professional investigate the cause and remove the mould.

Where does mould on the wall come from?

Mould grows where it stays damp for a long time. The most common causes are:

Condensation: warm, moist air condenses on cold surfaces such as outside walls, corners and around window frames. Think of showering, cooking and drying laundry indoors.
Too little ventilation: vents closed, no extractor in the bathroom, windows that never open.
Leaks: a leaking pipe, a broken gutter or a crack in the facade that lets water in.
Cold spots: poorly insulated parts of the wall where moisture keeps collecting in the same place.

⚠️ Do you see damp patches that grow, wet spots after rain or a musty smell without a visible cause? Then there is probably a leak. Have a leaking pipe repaired by a certified installer and a leak in the roof or facade by a professional.

What do you need?

A bucket of lukewarm water and a mild cleaner, for example Fila Brio universal cleaner or Fila Cleaner Pro cleaner. Always read the label and test on an inconspicuous spot first.
A sponge such as the floor sponge, or a soft cloth that you throw away afterwards. Use a clean 12-litre bucket.
Optionally a 2-litre hand pressure sprayer to mist the cleaning solution lightly so you do not have to scrub. Use that sprayer only for cleaning agent.
masking film and blue painter's tape to protect the floor and skirting.
A rechargeable LED work lamp to see clearly whether you have removed everything.
PPE: see below.

Working safely: PPE

You do not want to breathe in mould spores and cleaning agents or get them in your eyes. So always wear:

Gloves: work gloves with nitrile coating protect your hands from the cleaner and the mould. You can read more about the right choice in our buying guide for work gloves.
Safety glasses: safety goggles prevent splashes in your eyes, especially when working overhead.
Dust mask: an FFP2 dust mask or, for more than a few small spots, an FFP3 dust mask limits inhaling spores.
Ventilation: open a window while you work and keep children and pets out of the room.

⚠️ Never mix different cleaning agents. Chlorine-based products combined with ammonia or acids release toxic fumes. Use one product and follow the label.

You can read more about working safely in our blog on safe working on the construction site.

Step by step: removing small patches of mould

Assess the spot. Is it a few separate spots on a painted or tiled wall? Then you can carry on. Is it a large area, is it deep in the plaster or does it keep returning? Stop and call in a professional.
Protect the surroundings. Lay masking film on the floor and tape the edges. Move textiles and furniture away.
Dampen the spot. Never brush or sand mould away dry: that spreads the spores through the room. Lightly moisten the spot with the cleaning solution first.
Clean. Wipe the spot with a sponge and the solution, from the outside inwards, so you do not smear the mould. Rinse the sponge often in clean water.
Rinse and dry. Wipe the wall with clean water and let it dry thoroughly. Open the window or, in a larger room under renovation, use a construction dehumidifier.
Clear up. Put cloths, film and gloves straight into a closed bag and wash your hands.

Hands in yellow household gloves cleaning a wall with a spray bottle and a blue sponge

Refinishing the wall

Is the wall completely dry and clean? Then you can restore it:

If there is loose paint, scrape it off carefully with a paint scraper. Do this damp and with a dust mask.
On an absorbent surface apply a deep-penetrating primer so the new coat of paint adheres well.
Paint with a velour roller and touch up corners with a acrylic brush. How to do that step by step is explained in our blog on painting a wall.

In the bathroom and kitchen choose a paint that is suitable for damp rooms. Painting over without cleaning first is pointless: the mould simply grows through the paint.

Preventing mould

Ventilate every day. Open the vents, let the extractor run for a while after showering and open a window after cooking.
Dry laundry outside or in a well-ventilated room.
Keep furniture a few centimetres from the outside wall, so air can circulate behind it.
Heat evenly. Cold rooms that are occasionally heated a lot get condensation sooner.
Dry the bathroom after showering with a squeegee or cloth.
Check your home before winter. You can find tips in our blog on getting your home ready for winter.

When do you call a professional?

When the mould covers a large area or is in several rooms.
When it is in the plaster, behind wallpaper, in the crawl space or on woodwork.
When it comes back within a short time despite good ventilation.
With a leak, damp walls or rising damp: have a professional establish the cause and a certified installer repair the pipework.
When you or a member of the household has health complaints.

A professional is never superfluous. They find the cause and stop you from cleaning the same spot again and again.

Frequently asked questions

Can I just paint over mould?

No. Remove the mould first, let the wall dry thoroughly and deal with the cause. Otherwise the mould grows through the new coat of paint.

Is mould on the wall harmful?

Mould spores can cause respiratory complaints, especially in people with asthma or allergies. So work with a mask, gloves and glasses and ventilate well. If you have complaints, consult a doctor.

Why does the mould keep coming back?

Usually the cause is still there: too little ventilation, condensation on a cold wall or a leak. If mould keeps returning, have a professional take a look.