What kills black mould on walls permanently?

A bleach solution (1 part bleach to 4 parts water) kills black mould effectively. For permanent results, you must also address the moisture source and redecorate with anti-mould paint. Without fixing the cause, mould will return.

Can I paint over mould on walls?

Never paint directly over mould — it will grow through the paint within weeks. Always kill and remove the mould first, then treat with an anti-mould primer before repainting.

Is mould on walls covered by house insurance?

Standard buildings and contents insurance typically doesn't cover mould caused by condensation. Mould resulting from a sudden water leak (burst pipe, roof leak) may be covered. Check your policy and contact your insurer.

How do I stop mould coming back in a bathroom?

Run the extractor fan during and for 15 minutes after every shower. Keep a window open where possible. Wipe down shower walls after use. Wash towels and bath mats regularly. Use anti-mould bathroom paint when redecorating.

When should I call a damp specialist instead of a decorator?

If mould returns repeatedly despite treatment, if there are tide marks on walls, if skirting boards are soft or damaged, or if you see efflorescence (white chalky deposits) on walls, you likely have rising or penetrating damp which needs specialist treatment.

How to Get Rid of Mould on Walls

In This Guide

Is Black Mould Dangerous?What Causes Mould on Walls?Safety First Step 1 — Kill the Mould Step 2 — Scrub and Remove Step 3 — Dry Thoroughly

Is Black Mould Dangerous?

Black mould (Aspergillus niger and Stachybotrys) produces spores that can cause respiratory problems, allergies, and aggravate asthma — especially in children, the elderly, and people with existing health conditions. Always take mould seriously and remove it promptly.

What Causes Mould on Walls?

Mould grows where there is moisture, warmth, and poor ventilation. Common causes in UK homes include condensation from cooking and bathing, inadequate ventilation, cold bridges in poorly insulated walls, and underlying damp from leaking pipes or rising damp.

Safety First

Before tackling mould, protect yourself. Wear rubber gloves, an N95 or FFP2 respirator mask, and safety glasses. Open windows for ventilation. Never mix bleach with other cleaning products.

Step 1 — Kill the Mould

Mix one part bleach with four parts water in a spray bottle, or use a proprietary mould spray (HG Mould Spray or Dettol Mould and Mildew are effective). Spray directly onto the mould and leave for 10–15 minutes.

Step 2 — Scrub and Remove

Scrub the treated area with a stiff brush or old toothbrush for grout lines. Wipe clean with a damp cloth. Bag and dispose of the cloth immediately — don't reuse it. Rinse the area with clean water.

Step 3 — Dry Thoroughly

Dry the area completely with a clean cloth or fan heater. Mould returns wherever moisture remains. Ensure the room is well ventilated for several hours after cleaning.

Step 4 — Prevent Regrowth

Apply a specialist anti-mould paint or primer to the cleaned area. Ronseal Anti-Mould Paint and Zinsser Mold Killing Primer are widely available and effective. Address the root cause — improve ventilation, fix leaks, or add insulation.

When to Call a Professional

If mould covers a large area (more than 1 square metre), if it keeps returning despite treatment, or if you suspect rising damp or penetrating damp, call a specialist. Decorators can repaint with anti-mould paint after treatment.

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