Keeping a Basement Free From Damp & Mould – A London Homeowner’s Guide

Keeping a Basement Free From Damp & Mould – A London Homeowner’s Guide

3rd July, 2025

Many London homes have below ground living space, especially with older Victorian properties; a time when cellars were all the rage and as London sits on a low-lying area, damp-proofing is essential. In this short blog, we offer a London homeowner’s guide to keeping a basement free from damp and mould.

Inspect all seals regularly

You should be actively looking for any signs of water penetration, closely inspecting all seals on floors, walls and ceilings. Any signs of water penetration should be immediately investigated; using a silicone sealant, you should repair any breaches and if that is not something you are happy doing, there are competent damp-proofing services in London. If you would like your basement inspected by a professional damp surveyor, we at London Damp Surveys cover all London Boroughs.

Ensure good ventilation

Using extractor fans, you can ensure good ventilation in your basement; if you do not have extractor fans, we advise you to install at least two, with reversable directions, so that you can control the airflow. Of course, there should be a series of air vents that were installed during the build and these should always be open.

Monitor humidity levels

Investing in a hygrometer is wise and if the relative humidity is above 70%, you should use a dehumidifier to dry out the space. You can buy a portable dehumidifier and that can be used in all rooms of the house, which is a very effective way to remove excess moisture. Try not to allow the basement to get cold, as condensation could form and if it does, it should be wiped up as soon as possible.

Inspect exterior drainage

Downpipes and guttering should be checked often to ensure there are no blockages; if the ground slopes towards the house, consider grading to slope away from the building, as this will reduce the risk of water penetration. If the ground holds water, it might be best to have a drainage ditch dug and filled with shingle to aid water drainage.

Pipe insulation

All pipes should be insulated to avoid condensation forming, especially in the cold weather; you can buy pipe insulation from your local hardware store or better still, search online and place an order. The best insulation material is special foam that is thick enough to be a thermal break.

The importance of keeping a basement clean

It is very important to maintain a clean environment in a basement; we recommend using a chemical cleaning product mixed with hot water and carrying out a thorough clean at least twice a year. Whether you use it for storage, a wine cellar or a man cave, keeping the space clean is important if you wish to prevent mould from forming.

If you would like a professional damp inspection of your basement, call London Damp Surveys on 0207 395 5997 or fill in the form on this website.