How to Remove Mould on Walls Safely

Mould on walls develops when spores encounter moisture, limited airflow and a suitable surface on which to grow. Removing the visible patch can improve the room, but the effect will be short-lived if the damp penetration, leak or condensation feeding the fungus remains unresolved.

What should you check before starting to clean?

Begin by assessing the scale of the issue and finding the source of the moisture. Small patches on durable surfaces can usually be dealt with at home, whereas extensive areas, damaged walls or recurring mould may require professional repairs.

• Check roofs, pipes and windows for leaks;
• Look for signs of condensation in bathrooms and kitchens;
• Move furniture away to inspect the concealed wall area;
• Wear gloves, eye protection and a suitable mask;
• Open doors and windows before using any product;
• Keep children and pets away while cleaning.

How do you remove a small patch of mould on a wall?

Dampen the affected area before scrubbing so that spores are less likely to spread around the room. On a washable surface, use water and detergent, gently scrub with a sponge or soft brush, then wipe away the residue using a clean cloth. Finally, dry the wall thoroughly.

The method for removing mould stains can differ according to the paint and wall covering. Test any solution on an inconspicuous spot first, as harsh products may bleach the paintwork or damage the finish.

Which mistakes should be avoided during cleaning?

The most frequent mistake is painting straight over the stain. Paint only conceals the issue for a while and may peel if moisture is still coming through the wall. You should also avoid scraping or brushing the fungus when it is completely dry.

• Do not mix bleach with vinegar, ammonia or detergents;
• Do not use several products at once;
• Do not sand a mouldy wall without protective equipment and dust control;
• Do not put furniture back before the surface is dry;
• Do not use anti-mould paint to conceal damp penetration;
• Do not reuse contaminated cloths without washing them properly.

When can bleach be used?

Bleach is not needed for every cleaning task and may not soak properly into porous materials. For painted walls and hard-wearing surfaces, it is best to start with water and detergent, physically remove the mould and dry the area. Plasterboard, wallpaper and other heavily contaminated materials may need replacing.

If you use a chlorine-based product, follow the dilution instructions on the label precisely, keep the area ventilated and wear protective equipment. Never mix bleach with another cleaning product, as this combination can release dangerous gases.

How can you prevent mould from returning?

The essential measure is moisture control. Repair damp ingress, use extractor ventilation in bathrooms and kitchens, open windows every day, and leave a gap between furniture and cold walls. Dry wet surfaces quickly so the fungus cannot find the conditions it needs to grow again.

If the stain comes back soon afterwards, there is a strong damp smell, or the affected area approaches one square metre, seek specialist assistance. It is only advisable to apply a sealant and repaint once the cause has been removed, the surface has been cleaned and it has dried completely.