Mould Problems
Mould is a building-physics problem, not a cleaning one. It grows where surfaces stay cold and humid — so the cure is warmer surfaces and better ventilation.
Why does mould keep coming back?
Mould keeps coming back because cleaning and painting over it treats the symptom, not the cause. Mould grows wherever a surface stays cool and humid for long enough — so until those conditions change, it returns.
Read the guideWhy is there mould behind furniture?
Mould behind a wardrobe or sofa is a classic condensation pattern: a cold external wall, trapped air with no movement, and indoor humidity that climbs against the cold surface until mould takes hold.
Read the guideWhy is there mould in my bedroom?
Bedrooms are one of the most common places for mould because they combine a high overnight moisture load, cold surfaces and often poor ventilation — the exact conditions condensation and mould need.
Read the guideIs black mould caused by condensation, damp or ventilation?
Black mould is almost always a condensation problem — humid indoor air meeting cold surfaces — made worse by inadequate ventilation. Genuine penetrating or rising damp is a far less common cause, though it does happen. Telling them apart is the key.
Read the guideWhy is there mould in my bathroom?
Bathrooms are the highest-moisture room in most homes, so when that moisture is not removed quickly by ventilation it condenses on cold surfaces — the ceiling, the wall above the tiles, the corners and the sealant — and mould follows. Bathroom mould is rarely a cleaning problem; it is a moisture-and-ventilation problem. Stopping it means removing the steam at source and keeping surfaces warm enough not to condense.
Read the guideWhy is there mould on my ceiling?
Mould on a ceiling is usually condensation: the ceiling runs cold — often because the loft or roof above is poorly insulated or air leakage chills it — and humid room air condenses on it, especially in the corners and along the cold perimeter. It can also follow moisture from a room or roof above. Either way, it is a building-physics problem about cold surfaces and moisture, not just a stain to paint over.
Read the guideWhy is there mould on my clothes and belongings?
Mould appearing on clothes, in wardrobes, on shoes and on stored belongings means the air around them is humid and the surfaces are cold and still — usually in a wardrobe against a cold external wall, or in an unheated, poorly ventilated room. The items are not the problem; they are sitting in exactly the conditions mould needs. The fix is to lower the humidity, warm the cold surface and let air move around the belongings.
Read the guideIs black mould in my home dangerous to health?
Black mould can affect health — it can trigger or worsen respiratory problems, allergies and irritation, and the risk is greater for babies, the elderly, and anyone with asthma or a weakened immune system — so it should not be ignored. But cleaning it off treats only the symptom: mould grows because a surface is repeatedly damp, so the lasting protection for your health is to remove the moisture that feeds it. Understanding both the health risk and the real cause is what lets you deal with mould properly rather than fighting it forever.
Read the guideWhy is there mould around my windows?
Mould around windows is almost always caused by condensation: the glass, frames and reveals are the coldest surfaces in the room, so moist indoor air condenses on them, the water runs down onto the sills, frames and surrounding plaster, and those repeatedly damp surfaces grow mould. The reveals and corners around the window are particularly prone because they are colder still and often poorly ventilated behind blinds and curtains. It is a cold-surface and humidity problem, fixed by warming the surfaces and managing moisture, not by cleaning alone.
Read the guideIs mould in my rented home the landlord's responsibility?
Mould in a rented home is, in most cases where it stems from the condition of the building, the landlord's responsibility — but the question turns on what is actually causing it, and that is where tenants and landlords often disagree. If the mould results from a building defect or from inadequate provision the landlord is responsible for — cold, uninsulated walls causing condensation, a leak, or ventilation that does not work — then it is generally the landlord's to remedy. Landlords frequently attribute it instead to 'lifestyle'. The way to resolve that is independent, measured evidence of the cause: showing whether the building, not the occupant's normal use, is producing the conditions in which mould grows.
Read the guideWhy is there mould in my wardrobe or cupboard?
Mould in a wardrobe or cupboard almost always forms for the same reason: it is a still, unventilated pocket of air pressed against a cold external wall, so moist air condenses on the cold surface behind it and mould grows on the back panel, the wall and your belongings. The contents block air movement and trap humidity, while the wall behind — usually an uninsulated external wall — stays cold enough to condense. It is a localised condensation problem, and it is solved by warming that cold surface, letting air move behind the furniture, and reducing the room's humidity, rather than by repeatedly cleaning the mould off.
Read the guideHow do I get rid of mould permanently?
Getting rid of mould permanently means removing the conditions it needs to grow, not just cleaning what you can see. Mould needs a surface that is cold and humid enough for moisture to settle on it; cleaning or painting over it treats the symptom, so it returns within weeks or months because the cold, damp surface is still there. The permanent cure is to warm the surface (so it stays above the dew point) and lower the indoor humidity (so moisture isn't deposited) — usually a combination of insulation, heating and ventilation. Clean the mould, yes, but only as the last step after you have removed the cause.
Read the guideWhy does mould grow in the corner of my room?
Mould forms in the corner of a room because corners are colder than the flat walls around them — they are a thermal bridge — so they fall below the dew point of the room air first and stay humid enough for mould to grow. An external corner has more outside surface losing heat than inside surface to be warmed, and air circulation is poorest right in the corner, so it is consistently the coldest, least-ventilated spot in the room. Add normal indoor humidity and you get the classic patch of mould in the top or bottom corner of an external wall. The fix is to warm that corner and lower the humidity.
Read the guide