Why is only one room in my house mouldy?
The short answer: that room is different
When mould keeps appearing in one room and nowhere else, the air in your home isn't the whole story. Something about that particular room makes it colder, wetter or stiller than the rest of the house. That is good news, because a problem confined to one room usually has a cause you can pin down, and once it is fixed the mould has nothing to come back to.
Most of the time the answer is one of five differences, and quite often two of them working together.
Five differences worth checking
- A colder wall. An outside wall facing north, a corner with two exposed sides, or a room over an open undercroft stays cooler than the rest of the home, so moist air turns to water on it first. That is condensation at work.
- Less fresh air. A spare room kept shut, a bedroom where the window never opens in winter, or a shower room without a working fan all hold on to moisture. Here is how stale air feeds mould.
- More moisture going in. Showers, cooking and an airer full of washing release a lot of water, which is why drying clothes indoors so often marks out one room.
- Water from outside or from a pipe. A cracked roof tile, a failed seal on a balcony above, or a weeping pipe in the wall can wet one patch and leave the rest dry. These leaks tend to leave a stain with a clear edge.
- Contact with the ground. A ground-floor bedroom or a room cut into a slope can draw damp up from below, usually showing as a tide mark low on the wall.
Why it is often a bedroom in Cyprus homes
Many Cypriot houses are built to stay cool in summer, which leaves some rooms chilly through the winter. A back bedroom on the shaded side, heated now and then with a portable gas heater, collects moisture from the heater itself as well as from people sleeping with the door shut. An air-conditioner that runs in heat mode can warm the air without moving much of it out. The result is warm, damp air settling on the coldest wall in the house.
Narrowing it down yourself
Treat it like a comparison. Put your hand flat on the mouldy wall, then on an inside wall in the same room: if the mouldy one feels noticeably colder, condensation is the likely driver. Check the window first thing in the morning; heavy water on the glass points the same way. Note where the growth sits. Patches high in corners and behind furniture suggest condensation, while a single stain under a ceiling or along a pipe route points to a leak, and marks along the skirting point to the ground. Then ask what happens in the room: drying, showering, sleeping with the door closed, or nothing at all.
What you can do in the meantime
Wipe small surface patches with a damp cloth and a mould cleaner, wearing gloves and a mask and with the window open. Don't brush it off dry, and don't mix cleaning products. Pull wardrobes and beds a little away from the outside wall so air can reach it, open the window fully for a short spell each day, and keep the door open when the room isn't in use. If laundry dries in there, move it.
When the pattern needs a closer look
If the patch is back within a short time of cleaning, the wall feels damp rather than just cold, or you can't tell which of the five causes applies, guessing gets expensive. We find the cause before we touch the mould, so the fix lasts. A room-by-room damp check takes moisture readings in every affected room and ends with a moisture map sent to your phone, so you can see exactly how the problem room differs from the others. Typical fixes in the report include upgrading the extractor, insulating the cold spot and finishing in an anti-mould coating, and clearing the growth from that room's walls is usually one visit with no building work.
One room that won't stay clear? book an inspection from €75 or call +357 99 759144.