Clean mould safely and fix the moisture source before repainting
Wear suitable protection, avoid dry brushing large areas and stop if the mould is extensive, linked to sewage or flooding, or affecting vulnerable occupants.
MOST LIKELY CAUSES
Start with moisture, airflow and cold surfaces
Symptom variations Match the exact location, smell and recurrence pattern. ⌄
- Musty smell when furniture moves
- Black spots on wall or backing
- Damp fabric or timber
- Mould only on external wall
- Problem returns after cleaning
Quick checks Simple checks before cleaning or redecorating. ⌄
- Check whether the surface is cold or visibly damp.
- Look for blocked airflow and furniture against walls.
- Measure humidity if possible.
- Check extractors, vents and recent water leaks.
- Identify whether porous materials are badly contaminated.
Step 1 — Move furniture and inspect fully Clean safely, dry fully and fix the moisture source before redecorating. ⌄
Check the wall, backing, floor and skirting.
Step 2 — Dry and clean both surfaces Clean safely, dry fully and fix the moisture source before redecorating. ⌄
Treat the wall and furniture materials where salvageable.
Step 3 — Improve spacing and airflow Clean safely, dry fully and fix the moisture source before redecorating. ⌄
Leave a permanent gap and avoid overloading the area.
Why mould grows here How this mould pattern develops. ⌄
Mould behind wardrobes, sofas and cabinets usually develops because air is trapped against a cold wall and moisture cannot dry.
Advanced checks Further diagnosis for recurring or hidden mould. ⌄
- Check humidity and wall temperature.
- Inspect for plumbing or penetrating damp.
- Assess insulation behind the wall.
- Check whether mould has entered porous furniture materials.
- Review room ventilation and heating pattern.
Tools and information needed Useful items for safe diagnosis and cleaning. ⌄
- Digital humidity meter
- Suitable mould cleaner
- Protective gloves, mask and eye protection
- Surface-temperature checks
- Inspection of ventilation, insulation and leaks
Parts or improvements that may help Common items linked to this problem. ⌄
- Humidity meter
- Mould cleaner
- Replacement furniture backing
- Ventilation improvements
- Insulation or damp repair materials
When to call a professional Conditions that should end basic DIY treatment. ⌄
- The affected area is large or keeps spreading.
- There is hidden water ingress, sewage or flood contamination.
- Timber, plaster or insulation is badly damaged.
- Occupants have asthma, allergies or other vulnerabilities.
- The source appears structural or inside a wall or roof.
- The smell or mould returns despite ventilation and drying.
Frequently asked questions Common mould questions. ⌄
Can mould-resistant paint solve the problem?
Only after the moisture source is controlled. Paint alone will not stop mould on a surface that keeps getting damp.
Should mould be painted over?
No. The area should be cleaned, dried and the cause fixed before redecorating.
Is bleach always suitable?
No. Product suitability depends on the surface and contamination. Use a cleaner intended for the material and follow its instructions.