Condensation and Black Mould
Condensation is the most common cause of damp and mould in UK homes, and it is not fixed by a damp proof course. We find why moisture is building up and cure it with the right ventilation, so the mould stops coming back. Survey-led, with a written guarantee.
Book a Condensation Survey
0300 373 7251Survey-led diagnosis with a clear, written report. No obligation.
What is Condensation?
Condensation happens when warm, moisture laden air meets a cold surface, a window, an external wall, a cold corner, and turns back into water. There is always moisture in the air, and an average household produces a surprising amount of it every day through normal living.
When that water settles on cold surfaces and cannot escape, it dampens them, and over time it feeds black mould, those pinpoint black spots in corners, around windows and behind furniture. It is by far the most common cause of damp in UK homes, and it is worst in the colder months.
It is also the most misdiagnosed. Because it can look like other damp problems, condensation is often wrongly treated as rising damp, with an injected damp proof course that does nothing to solve it. The right answer almost always lies in moisture, ventilation and warmth, which is what we assess with a survey.
Signs of Condensation
Condensation tends to follow the cold spots in a home. These are the signs to look for, especially in winter.
Streaming Windows
Water running down windows and sills, especially first thing on cold mornings, is the classic early sign of condensation.
Black Mould in Corners
Pinpoint black mould in room corners, on ceilings and around window reveals, where surfaces are coldest and air moves least.
Mould Behind Furniture
Mould on walls behind wardrobes, beds and sofas pushed against external walls, where trapped air cannot circulate.
A Musty Smell
A persistent damp, musty smell in a room, on soft furnishings or in wardrobes, even before mould is clearly visible.
Damp, Cold Walls
External and north facing walls that feel cold and damp to the touch, sometimes with peeling paint or wallpaper.
Mould on Fabrics
Mould spotting on curtains, clothes and leather in wardrobes and against cold walls, a sign of high humidity.
Is It Condensation, or Something Else?
This is the question that saves people money. Condensation is seasonal and shows on surfaces and cold spots, around windows, in corners and behind furniture, usually with black mould. Rising damp sits low on the wall with tide marks and salts. Penetrating damp shows as a patch that gets worse after rain.
They can look alike, but the fixes could not be more different. Treating condensation as rising damp, with an injected damp proof course, is one of the most common and costly mistakes in this trade, and it leaves the real problem untouched. Getting the diagnosis right is the whole point of a survey.
The honest version: if your damp is condensation, we will tell you, and we will not sell you a damp proof course you do not need.
The Three Causes
Condensation is almost always a mix of these three things, and lasting control usually means addressing more than one:
How We Fix Condensation
Survey and confirm the cause
We confirm it really is condensation, rule out rising and penetrating damp, and find the cold spots and humidity levels driving it, using moisture readings and where useful thermal imaging.
Reduce the moisture
We advise on the quick wins that cut moisture at source, from venting tumble dryers outside to how laundry is dried, so the air starts off drier.
Improve ventilation
The core of the fix. Extractor fans, trickle vents and often a Positive Input Ventilation unit to keep fresh, drier air moving through the home.
Warm the cold surfaces
Where cold walls and bridging are part of the problem, we advise on insulation and background heating so surfaces stay above the point where moisture condenses.
Treat the mould
Existing black mould is treated and removed properly, not just painted over, so you start from a clean, healthy surface.
Written guarantee
Ventilation installations are backed by a written guarantee, for lasting peace of mind.
Why It Pays to Fix It Properly
Wiping the windows every morning treats the symptom. Fixing the ventilation treats the cause, and that is what makes mould stop coming back.
What Our Customers Say
Genuine reviews from Advanced Damp customers.
"We contacted Advanced Damp to help us with a damp issue on one of our windows. Communication was prompt, easy, friendly and professional. The assessment was carried out thoroughly and competently by Lionel and the report was comprehensive."
"We had damp proofing work carried out recently and I'm really pleased with the service. The team were friendly, professional and explained everything clearly before starting. The work was done efficiently and the property was left clean and tidy afterwards."
"Lionel the surveyor arrived on time and he was very courteous and thorough, he discussed everything that needed doing and was able to reassure us during a very stressful time."
Related Services
Condensation, mould and ventilation all go together. These related services tackle the wider picture:
Condensation FAQs
What causes condensation in my home?
How can I tell condensation from rising or penetrating damp?
Why do I get black mould, and is it a health risk?
How do I stop condensation?
Will damp proofing or a new damp proof course fix condensation?
What is Positive Input Ventilation (PIV)?
Beat Condensation and Mould for Good
Book a survey and get a clear, written diagnosis of what is causing your condensation and exactly how to fix it, with honest advice including the simple steps that cost nothing.
Last updated June 2026 · Advanced Damp Ltd · Condensation and mould control nationwide · 0300 373 7251