Condensation control and ventilation in London
Condensation forms when warm, damp air hits something cold, such as a window, a bathroom wall or a bedroom corner with little airflow. Scrubbing off the black mould that grows there deals only with the visible part and leaves the cause in place. A lasting fix has two parts. Remove the moisture from the house before it can condense, and get rid of the cold spots where it collects.
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- Engineers who are DBS-checked
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What the job covers
- Fitting and repairing extractor fans in kitchens and bathrooms
- Upgrading to fans run by a humidity sensor or timer
- Positive input ventilation (PIV) systems
- Checking trickle vents and passive ventilation
- Finding cold spots and cold bridging that cause condensation
- Mould treatment after the ventilation fix, never in place of it
Things to check before booking
A few of these points could mean you need no visit at all. We would sooner you knew that.
Moisture causes black mould, and the mould is only the sign
Wipe mould away but leave the humidity behind it, and it is back within weeks. So each job begins by asking why the air is so damp, before any surface gets treated.
The trouble is often a fan that stops when the light goes off
After a shower finishes, steam hangs in the air for quite some time. A fan with a humidity sensor, or a timer that keeps it going once the light is off, clears that moisture instead of cutting out with the switch.
Washing dried indoors adds a lot of avoidable moisture
Just one load of laundry dried inside puts a surprisingly large amount of water into the air. With no garden or tumble dryer, that moisture has to be taken out by good extraction or a dehumidifier. Keeping the window shut does the opposite.
Trickle vents are often painted shut without anyone noticing
The small vents in window frames are regularly painted or sealed during decorating, which quietly takes away the background airflow the room was designed to rely on. It takes two minutes to check they still open, and it is worth doing.
Questions people ask us
How can I tell condensation apart from penetrating or rising damp?
Condensation tends to form on cold surfaces such as windows, north-facing walls and corners where air barely moves. It gets worse in cold spells and with cooking, showers or laundry drying. If it is not clear, a damp survey will decide it.
Is a dehumidifier enough by itself?
In the short term it helps, but it leaves the ventilation problem untouched. Running one all the time also works out dearer over the years than sorting the extraction properly.
Does fitting a new extractor fan also mean calling an electrician?
Only when the job needs new wiring or a switched supply that is not there yet. Plenty of replacement fans run off the existing wiring and are a simple swap.
Do you treat mould as well as fixing the ventilation?
Yes, though only together with the ventilation fix. Mould treatment on its own gives a short-lived result, and we will tell you that instead of selling it as a separate job.
When the cause is plumbing
If a leaking pipe or fitting is behind the problem, not damp as such, these pages explain that work.
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General Plumbing
Radiators, pipework, taps and toilets: the small jobs that keep getting put off.
Read about General Plumbing -
Leak Detection
Acoustic and thermal equipment to trace hidden leaks before any floor is lifted.
Read about Leak Detection
Other damp and condensation pages
Further reading
Looking for condensation control & ventilation in London?
Let us know the problem and your address, and you will hear the cost before any work begins.