Do dehumidifiers actually stop mould?
They stop new mould forming, not the mould you already have
A dehumidifier draws damp air in, takes water out of it and returns drier air to the room. Mould needs a surface that stays damp, so lowering the moisture in the air means less condensation on cold walls and windows, and fewer places for growth to start. For mould driven by condensation and everyday humidity, that makes a dehumidifier one of the most useful things you can own.
It has two limits. It won't kill or remove growth that is already on a wall, and it can't keep up with water getting into the building from a leak, the ground or outside.
Where one earns its keep
The rooms that benefit most are the ones where moisture builds up with nowhere to go: a bedroom with wet windows every morning, a room used for drying washing, a windowless box room or a basement. Seafront flats are a good fit, because opening a window on a muggy day can let in air almost as wet as the air inside; coastal humidity explains why. Homes shut up for long spells can benefit too, as long as the unit drains on its own rather than switching off when the tank fills (see closed-up holiday homes).
Choosing and using one well
- Type. Compressor models suit warmer rooms and are economical to run. Desiccant models keep working better in cold, unheated rooms, which makes them a common choice for winter.
- Placement. Put it in the problem room with the door and windows shut, away from walls and curtains so air can move freely around it.
- Drainage. Empty the tank daily, or run a hose to a drain if the model allows it.
- Feedback. A cheap hygrometer shows whether the room is actually getting drier, and dry glass in the morning is a good sign.
- Upkeep. Clean the filter and tank as the maker recommends, so the unit doesn't harbour mould itself.
Signs the problem is bigger than the air
If the tank fills every day but the patch on the wall keeps spreading, the moisture is probably coming from the building rather than the room. A stain that grows after rain, a band of damp low on a ground-floor wall with a crusty white bloom, or a wet spot that isn't especially cold all point that way. Drying the air there only hides the source for a while. The comparison of the three main types of damp helps you tell them apart.
Clear the mould first, then let the dehumidifier hold the line
Running a dehumidifier in a room with active growth will slow it, but spores stay on the surface and growth can return as soon as the room gets damp again. For a small patch on a hard surface, air the room, put on gloves and a mask, and wipe the area with a mould cleaner and a damp cloth. Don't brush it off dry or mix products, and dry it fully afterwards.
For larger areas, or mould that keeps returning, we find the cause before we touch the mould, so the fix lasts. Moisture readings in every affected room show whether the problem is the air or the structure, and the written report comes with the quote. Treatment to clear the growth before the dehumidifier takes over is usually one visit with no building work.
Not sure a dehumidifier is enough? book an inspection from €75 or call +357 99 759144.