How to Get Rid of Black Mould on Walls: A UK Homeowner's Guide

Black mould is one of the most common — and most unpleasant — problems in UK homes. It's not just unsightly; it can also cause health problems, particularly for people with asthma or allergies. The good news is that in most cases, you can tackle it yourself.

What Causes Black Mould?

Black mould (Aspergillus niger or Cladosporium) grows in damp, poorly ventilated areas. In UK homes, it's most commonly caused by:

• Condensation — the most common cause, particularly in bathrooms, kitchens, and bedrooms
• Rising damp — moisture rising up from the ground through walls and floors
• Penetrating damp — water getting in through the roof, walls, or windows

Before you treat the mould, it's important to identify and fix the underlying cause — otherwise it will just come back.

How to Identify the Type of Damp

Condensation

Condensation mould typically appears in corners, on cold external walls, and around windows. It's usually black or dark grey and appears in patches. You'll often notice it in bathrooms and kitchens, or in bedrooms where there's poor ventilation.

Rising Damp

Rising damp appears on lower sections of walls, usually within 1 metre of the floor. You'll often see a "tide mark" — a horizontal stain — and the plaster may be damp to the touch or crumbling.

Penetrating Damp

Penetrating damp can appear anywhere on walls or ceilings, often in patches that correspond to external defects (cracked render, blocked gutters, etc.).

How to Remove Black Mould Safely

Safety first: Wear rubber gloves, a face mask, and old clothes. Open windows for ventilation.

1. Mix a cleaning solution — a solution of 1 part bleach to 4 parts water works well, or use a proprietary mould remover spray
2. Apply to the affected area — use a sponge or cloth to apply the solution to the mould
3. Leave for 15–20 minutes — allow the solution to kill the mould spores
4. Scrub gently — use a stiff brush to scrub away the mould
5. Rinse and dry — rinse with clean water and dry thoroughly
6. Apply anti-mould paint — once the wall is completely dry, apply an anti-mould paint to prevent regrowth

How to Prevent Black Mould Coming Back

Improve Ventilation

The single most effective thing you can do to prevent condensation mould is improve ventilation. Open windows daily, use extractor fans in bathrooms and kitchens, and consider installing a whole-house ventilation system if condensation is a persistent problem.

Reduce Moisture

• Always use extractor fans when cooking or showering
• Dry clothes outdoors or in a well-ventilated room
• Keep lids on pans when cooking
• Avoid drying clothes on radiators

Keep Your Home Warm

Cold surfaces attract condensation. Keep your home at a consistent temperature — even a low background heat is better than letting it get very cold.

Fix Structural Issues

If you have rising damp or penetrating damp, you need to address the underlying cause:

• Rising damp: install or repair a damp-proof course
• Penetrating damp: fix the external defect (cracked render, blocked gutters, damaged roof tiles, etc.)

When to Call a Professional

If mould covers a large area (more than 1 square metre), if it keeps coming back despite treatment, or if you suspect rising or penetrating damp, it's worth getting a professional damp survey. A surveyor can identify the exact cause and recommend the right treatment.

Browse our damp solutions products or contact us for advice on your specific situation.

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