Condensation
Condensation is the most common cause of dampness in buildings, accounting for a significant proportion of reported damp problems. It affects both older and modern properties, but is particularly prevalent in buildings that have been upgraded with improved insulation, double glazing or draught-proofing without adequate ventilation.
At Bristol Damp Solution, we regularly assess condensation-related damp and mould issues as part of our professional survey services.
The Link Between Condensation & Mould
Condensation is closely associated with mould growth. Mould is often the first visible sign, typically appearing on decorative surfaces such as walls, ceilings and wallpaper. Over time, this can cause permanent staining and damage to internal finishes.
Mould growth and airborne spores can also contribute to health complaints and are responsible for the characteristic musty odour often associated with condensation problems.
Where Condensation Occurs
Condensation commonly forms on cold surfaces, including:
External walls
Windows and glazed areas
Cold floors
Corners and poorly insulated areas
It can also develop in less visible areas such as roof spaces and sub-floor voids beneath suspended timber floors. In these environments, prolonged moisture can contribute to wet rot or dry rot affecting structural timbers.
What Causes Condensation?
Warm air is capable of holding more moisture than cool air. Condensation occurs when moisture-laden air comes into contact with a colder surface and cools to a point where it can no longer retain that moisture. This temperature is known as the dew point.
When this happens:
On non-porous surfaces (such as glass or gloss paint), water forms as visible droplets
On porous materials (such as plaster or wallpaper), moisture is absorbed into the surface, making the problem less immediately obvious
Identifying Condensation Problems
Condensation is typically a seasonal issue, most noticeable during the colder months from autumn through to spring. During warmer months, symptoms often reduce or disappear, leading to the false impression that the issue has resolved.
Reduced ventilation during winter — caused by closed windows, sealed buildings and draught-proofing — allows moisture from everyday activities (cooking, bathing, drying clothes) to build up indoors.
Common signs include:
Water droplets on windows or painted surfaces
Damp-feeling or discoloured wallpaper
Black mould growth
Mould appearing intermittently at certain times of day or night
In some cases, moisture may evaporate before inspection, leaving mould growth as the only visible indicator.
Professional Condensation Assessment & Control
Effective control of condensation requires identifying both moisture sources and ventilation performance. Simply cleaning mould or redecorating will not prevent recurrence.
Following a professional survey, appropriate solutions may include:
Improved background ventilation
Installation of air vents
Powered extractor fans in kitchens, bathrooms or utility areas
All works are specified based on survey findings and installed by fully qualified tradespeople to ensure effective, long-term results.