How to Clean Mould on the Wall

Mould on the wall develops when spores meet damp, poor ventilation and a surface they can colonise. Wiping away the visible mark can make a room feel better, but it will only be a short-term fix if the damp source-such as water ingress, a leak or ongoing condensation-remains.

What should you check before you start cleaning?

Start by working out how widespread the issue is and where the moisture is coming from. Small patches on durable, washable finishes can usually be dealt with at home. Larger areas, crumbling plaster, or mould that keeps returning may indicate the need for professional repairs.

• Check for leaks around roofs, pipework and window frames;
• Look for signs of condensation in bathrooms and kitchens;
• Move furniture away to inspect the wall behind it;
• Wear gloves, eye protection and a suitable mask;
• Open doors and windows before using any product;
• Keep children and pets away while you clean.

How do you clean a small patch of mould from a wall?

Dampen the affected area before scrubbing so spores are less likely to become airborne. On a washable surface, use warm water with washing-up liquid, gently rub with a sponge or soft brush, then wipe away residue with a clean cloth. Afterwards, dry the wall thoroughly.

How you tackle mould staining can change depending on the paint and wall covering. Before applying any solution, test it on a hidden spot, as stronger products can bleach paintwork or damage the finish.

Which mistakes should you avoid during cleaning?

A frequent mistake is painting straight over the mark. Paint may cover it briefly, but it does not solve the underlying damp and can peel once moisture continues to pass through the wall. You should also avoid scraping or brushing mould when it is completely dry.

• Do not mix household bleach with vinegar, ammonia or detergents;
• Do not apply multiple products at the same time;
• Do not sand a mouldy wall without protection and proper dust control;
• Do not push furniture back until the surface is fully dry;
• Do not use anti-mould paint to disguise water ingress;
• Do not reuse contaminated cloths without washing them properly.

When can household bleach be used?

Household bleach is not required for every clean, and it may not soak into porous materials effectively. On painted walls and other hard-wearing surfaces, it is better to begin with water and washing-up liquid, physically remove the mould, and then dry the area. Plasterboard, wallpaper and other heavily contaminated materials may need replacing.

If you do use a chlorine-based product, follow the label dilution exactly, keep the space well ventilated and wear protective equipment. Never mix household bleach with any other cleaning product, as the combination can release dangerous gases.

How can you stop mould from coming back?

The key is humidity control. Fix leaks and water ingress, use extraction in bathrooms and kitchens, open windows daily, and leave a gap between furniture and cold external walls. Any damp surfaces should be dried quickly so the fungus does not get the conditions it needs to grow again.

If the patch reappears soon after cleaning, there is a strong damp smell, or the affected area approaches 1 square metre, seek specialist help. Only once the cause has been removed, the surface has been cleaned, and everything is completely dry should you apply a primer/sealer and repaint.