 A Guide to Damp & Mould Prevention
Damp and mould have one main cause: excess moisture in the air. Everyday activities like cooking, showering, and even breathing all add moisture. When warm, damp air meets a cold surface like a window or external wall, it condenses into water droplets. Left unchecked, this leads to damp patches and mould growth.
To prevent this, CCS install whole-house ventilation systems that continuously remove excess moisture. This guide explains how it works and what you need to do to keep it running properly.
How Your Ventilation System Works
This section applies if CCS has fitted a ventilation system in your home.
Your system has two key components:
- Continuous extractor fans. Fitted in wet rooms (kitchens, bathrooms, WCs) where most moisture is produced.
- Door undercuts. Gaps under your internal doors allow air to move freely around the home.
The fans pull damp, stale air out of wet rooms. This draws in drier, fresher air from the rest of the home through the door undercuts, creating a constant cycle that prevents moisture from building up. The whole house is designed to work as a single system. All elements work together to create a fresh and safe environment in your home.
Understanding Your Extractor Fan
Your fan is designed to run continuously — 24 hours a day, 7 days a week. It uses very little energy (less than a low-energy lightbulb), but it's essential for keeping your home free from damp.
Do not turn it off at the isolator switch.
Trickle speed — The fan runs constantly at a very low, quiet speed. This is normal and provides background ventilation for the whole home.
Boost speed — The fan automatically switches to a higher speed when it detects increased moisture. This happens in two ways:
- An internal humidity sensor boosts the fan during activities like showering or cooking, then returns it to trickle speed once the moisture clears.
- In bathrooms, the fan is often linked to the light switch. It boosts when the light is on, then continues running for a set period after the light is switched off to clear any remaining steam.
Why the Gaps Under Your Doors are Crucial
The undercuts beneath your internal doors are essential as they allow drier air to flow towards the fan in the bathroom or kitchen, replacing the damp air being extracted.
If these gaps are blocked, the system can't work properly. Airflow is restricted, and moisture will build up in wet rooms.
Do not block door undercuts with rugs, towels, or draught excluders.
What to do if you suspect a problem
If you're seeing condensation on windows or early signs of mould, the ventilation system may not be working correctly. Here are the most common causes:
The fan has stopped completely
- Check the isolator switch (often a pull-cord in the same room, or a fused spur outside the door), it should be permanently switched ON.
- Check your fuse box for any tripped switches and try resetting once. If it trips again, call for maintenance.
The fan doesn't seem to be clearing steam
- The fan may be blocked with dust. Clean it regularly using the steps below:
- Turn the fan OFF at its isolator switch.
- Remove the front cover (usually an anti-clockwise twist).
- Use the soft brush attachment of a vacuum cleaner to gently remove dust from the blades and grille. Wipe the cover with a damp cloth.
- Refit the cover and switch the fan back ON.
Airflow feels restricted
- Check that door undercuts are clear and unobstructed.
- If your windows have trickle vents, make sure they are open.
