Condensation & mould
Why the mould keeps coming back
Cleaning mould removes what you can see. It doesn't change the conditions that grew it. If a surface keeps getting cold and damp, the mould returns — usually within weeks.
If the problem isn't condensation, we'll tell you straight. We won't sell you a fan to cover up a leak or a building defect.
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The signs
Symptoms we see in Scottish homes every week
These are symptoms, not diagnoses. The same black mould in a bedroom corner can come from more than one cause.
Black mould keeps coming back after cleaning
Wiped down, repainted, and back on the same wall or corner within weeks.
Bathroom ceiling or walls going black
Mould spreading across the ceiling, sealant and grout no matter how often it's cleaned.
Windows soaking wet in the morning
Puddles on the sills and water you have to mop up before you open the curtains.
Condensation running down the glass
Steamed-up windows all winter, with damp frames and blackened beading.
Mould in bedroom corners and behind furniture
On the cold external corner, behind the wardrobe, on curtains, shoes and clothes.
A musty smell that never clears
That damp smell in a bedroom, cupboard or hallway, even after airing it out.
The bathroom stays wet long after a shower
Mirrors and tiles still streaming an hour later — a sign the extraction isn't shifting the moisture.
The extractor fan isn't coping
Noisy, weak, only on with the light, or not properly ducted to outside at all.
What's behind it
Four things we look at
Moisture generated indoors
Showering, cooking, drying washing on radiators and simply breathing all add water to the air. In a well-sealed home with weak extraction, that moisture has nowhere to go.
Cold surfaces
Warm, moist air meets a cold window, an external corner or an uninsulated wall and condenses there. That's why mould appears on the coldest surfaces first.
Inadequate ventilation
Intermittent fans wired to the light switch, crushed or disconnected ducting and missing trickle vents leave moisture in the room long after the shower has finished.
Something else entirely
Plumbing and roof leaks, penetrating damp through failed render or pointing, cold bridging, missing insulation and underheating can all look like a condensation problem. If that's what the evidence shows, we say so.