Part of Ward Property Services UK LtdCondensation
How To Prevent Black Mould For Good
What mould needs to grow
Mould needs moisture, a food source and a tolerable temperature. In homes the food source is everywhere — dust, paint, wallpaper paste, plaster — and the temperature is nearly always suitable. Moisture is therefore the only variable you can control, and it is the one that matters.
The threshold is surface humidity rather than room humidity. A wall corner at 14°C in a room at 55% relative humidity can easily sit above 80% humidity at the surface, which is ample for growth. That is why mould appears in specific spots rather than evenly.
Removing it safely
Do not dry brush or vacuum with a domestic cleaner — both disperse spores through the house. Wipe with a proprietary fungicidal wash, allow the product its stated dwell time, and dispose of cloths afterwards. Wear gloves, eye protection and a mask, and ventilate while you work.
Soft furnishings, heavily affected wallpaper and mould-stained sealant are usually best replaced rather than cleaned. Where growth has been present for years, plaster may be contaminated and need removal.
Stopping it returning
Reduce moisture at source with proper extraction in bathrooms and kitchens, then add background ventilation so the whole house exchanges air steadily. Raise surface temperatures where cold bridging is severe — insulated reveal boards, thermal linings or improved cavity insulation.
Finally, redecorate with a breathable, fungicidal system rather than a vinyl paint, and keep furniture clear of external walls. Where a household has vulnerable occupants, a small humidity monitor is a worthwhile purchase so problems are spotted before growth appears.
Common questions about this topic
Is black mould a landlord's responsibility?
Where mould results from a disrepair issue such as a leak, defective ventilation or failed damp proofing, it is generally the landlord's responsibility to remedy.
Does anti-mould paint work on its own?
It slows regrowth but does not remove the cause. Used alongside ventilation and insulation improvements it is very effective.
Need professional advice?
Book an independent damp survey and get a written diagnosis for your property.