Mould on the bathroom ceiling: why it keeps coming back
Why it keeps coming back
Ceiling mould returns because cleaning deals with the growth but not with the steam. Every shower sends warm, wet air straight up, it gathers against the ceiling, and if that surface is cold the moisture condenses there again within days of a clean. Mould also roots a little way into paint and plaster, so a wipe that leaves the ceiling looking clear can leave enough behind to regrow, which is why mould so often returns after cleaning. Until less water reaches the ceiling, or the ceiling stops being cold, the spots will be back.
Why that particular spot
Look at where the mould sits. A cluster directly over the shower shows where the steam hits hardest. A line along the edge where the ceiling meets an outside wall marks the coldest strip of the room. A patch in a corner far from the fan shows air that never gets drawn out. In top-floor flats under a flat concrete roof, the whole ceiling can turn cold in winter, which is why mould there often appears once the weather turns and fades in summer (see why mould grows in winter).
Is your extractor doing its job?
Most recurring ceiling mould comes down to extraction. A few quick checks:
- Hold a single sheet of toilet paper against the grille while the fan runs. If it isn't pulled flat, very little air is moving.
- Clean the grille; a coat of fluff and dust can choke a small fan.
- Notice whether it stops as soon as the light goes off. A fan that runs only while you're in the room leaves most of the steam behind.
- Look at the mirror and ceiling a little while after a shower. If they're still dripping, the fan is too weak for the room or the duct is blocked.
- Listen for a fan that hums but barely turns, which usually means it's worn out.
If there's no fan at all, open the window wide as soon as you finish and leave it open until the glass has cleared.
Leak or condensation?
Condensation mould is usually black or grey speckling with no staining around it. Brown or yellow rings, a patch well away from the shower, bubbling paint, or a soft, sagging area point to water coming from above, whether from a bathroom upstairs, the roof, or a water tank or solar heater on top of the building. That needs tracing and repairing the leak before any cleaning, because no amount of ventilation will dry it.
Cleaning it overhead
Use a steady step-ladder, and wear gloves, a mask and eye protection, since anything you loosen will fall towards your face. Put the mould cleaner on a cloth or sponge rather than spraying it upwards, wipe gently, and rinse the cloth often. Keep the fan running and the window open while you work, and let the ceiling dry completely afterwards. Don't paint straight over it: painting over mould only hides it for a while. Once the ceiling is clean and dry and the cause is fixed, an anti-mould paint helps it stay that way.
Fixing the cause
Run the fan throughout the shower and well after it. If it's wired to the light, a model with an overrun timer or a humidity sensor keeps it going once you've left. Where the ceiling is cold because it sits under the roof or against an outside wall, better ventilation may never be enough on its own. A report will usually point to one or more of three fixes: a stronger extractor, insulation for the cold spot, or an anti-mould coating, depending on which is the weak link.
When to get help
If the mould has come back more than a couple of times, the paint is flaking, or the plaster feels soft, it's time to find out why. A check of the bathroom ceiling and the rooms around it includes moisture readings in every affected room and a room-by-room moisture map sent to your phone. Where moisture has got into the plaster, removing mould from a damaged ceiling means the growth is removed, the cause repaired and the surface finished in an anti-mould system.
Ceiling mould keeps coming back? book an inspection from €75 or call +357 99 759144.