About CondensationCheck
CondensationCheck is a free, independent website that helps people in UK homes understand condensation, damp and mould — and work out what will actually fix it.
Why we built it
Search for "damp" and most of what you'll find is written by companies selling damp treatments. Some of that advice is good. But condensation, rain penetration, leaks and ground moisture need different fixes, and getting the diagnosis wrong is expensive. We wanted a tool that starts with the cause, shows its reasoning, and is honest about what it doesn't know.
How we work
- Independent. We don't sell damp-proofing, ventilation or insulation, and nobody pays to appear in our results.
- Transparent. Every equation and default value is on our methodology page, with a version number and changelog.
- Evidence-led. Our guidance follows UK sources including Historic England, the Energy Saving Trust, the UK Health Security Agency and the relevant building standards.
- Private. The tools run in your browser; your answers aren't sent to us.
How the site is funded
The site is funded by advertising, shown in clearly labelled spaces. Advertisers have no influence on our tools or content. Where we link to measuring equipment we may earn a commission, which is always disclosed.
Corrections
If you spot an error or think a calculation is wrong, please tell us. We correct mistakes promptly and note significant changes in the methodology changelog.