The characteristic musty smell often appears months before the first visible patch. It is a useful early warning.
Growing fungus releases volatile organic compounds. Those are what create the characteristic musty, damp, "basement" smell. The human nose picks them up at very low concentrations — often before the eye notices the first patch.
That is useful. The smell is an early signal that gives you a chance to find the problem while it is still small. What is unhelpful is that the smell is usually "solved" with an air freshener or more frequent airing — and then it comes back, because the cause remains.
The smell is not an inconvenience. It is information that something somewhere in the room is growing.
The intensity of the smell changes with conditions, and that in itself is a diagnostic tool. It gets stronger when humidity or temperature rises: after a shower, in rainy weather, when the heating goes on, on warmer summer days. It also gets stronger after a longer absence, because the room has not been aired and your nose has lost its habituation.
A flat can have several unpleasant smells, and they call for completely different solutions.
The simplest check for the drainage case: pour water down every drain, including the ones you rarely use — the shower gully, the washing machine drain. If a trap's water seal has dried out, the smell is coming from the drainage, and it goes away within a few hours once water has been poured in. That does not happen with a mould smell.
If there is a smell but no patch, the fungus is most often in one of these places:
| Location | Why there |
|---|---|
| Under the floor covering | After flooding or a leak, water stays between the covering and the substrate |
| Behind fitted furniture | The wall behind it is cooler and out of sight |
| In ventilation ducts | Moisture and dust inside the duct |
| Under a sink or bath | An undetected slow leak at a trap or a joint |
| In a wall behind the finishes | A pipe leak inside the structure |
| In a basement or loft | The smell reaches the flat through the stairwell or the ventilation |
A practical technique: walk around the flat and pay attention to where the smell is stronger. It is often more pronounced near a particular wall, wardrobe or floor area — that points the way.
A second technique: coming home after a longer absence, the smell is far more noticeable. Day to day, your nose gets used to it.
What you can check yourself before anyone comes out:
The building type indicates where to look first. In pre-war buildings it is more often the timber floor structure and the basement level, from where the smell reaches the flat through the stairwell. In panel blocks it is the shared ventilation shaft and the zone under the floor covering after flooding from a neighbour. In new builds, during the first winters the smell often comes from a structure still giving off construction moisture into a room where the ventilation is not switched on.
With a smell, the work always starts with finding the source. Ozone treatment clears the smell, but if the fungus stays the smell will come back — so ozone treatment on its own is not the answer here, it is the last step.
We inspect the rooms and measure moisture to find where the fungus is growing.
Where necessary, we open up finishes at the point the readings indicate.
We remove the affected material and treat the structure.
We dry the structure back to normal moisture readings.
Only as the final step — it clears the remaining smell from the room and from textiles.
What decides the scope of work: how wide an area has to be checked, whether finishes have to be opened up anywhere to reach the source, whether the structure has to be dried and how easy the spot is to get at. If the source is under a floor covering or behind fitted furniture, providing access is a separate job, and we agree it before starting.
The first reaction to a smell is usually to hide it: a spray, a scented candle, a plug-in air freshener. That works for a few hours and creates two problems.
The first is obvious: the fungus keeps growing, and the one early warning you had is switched off. The smell was a useful instrument — it appears months before a patch and gives you a chance to find the problem while it is still small and cheap.
The second is subtler: the nose adapts. If a smell in a room is constant and also masked, people stop perceiving it altogether. That is exactly why visitors notice it and residents do not, and why it suddenly seems much stronger after coming back from a holiday — the nose has "reset" in two weeks.
Masking a smell means switching off the only warning you had.
Airing is a different matter — it genuinely reduces the moisture in a room and is part of the solution. But it too only removes the smell temporarily if the source stays. If the smell returns within a few hours of thorough airing, the source is in the room and it is worth looking for.
Put simply: ozone treats air and surfaces, not structures and not moisture. Used before the source is dealt with, the smell will return, and the only result will be paying for a step taken in the wrong order.
Inspection with moisture readings from €40. Ozone treatment €1.20/m², minimum order €60. If we find fungus, treatment from €1.50/m² — we give the exact price after the inspection.
For a while, yes. But if the fungus keeps growing, it keeps releasing the compounds that cause the smell, and it will come back. Ozone treatment is the last step, not the first.
Yes. The smell often intensifies with higher humidity or temperature — after a shower, in rainy weather, or when the heating goes on.
A drains smell is sharper and usually stronger near a drain or a trap. A mould smell is musty, of the “basement” type, and often more pronounced near a wall or the floor.
Describe the situation — we will tell you whether treatment is needed at all, and which one.
Fill in the form — we will call you on the number you provide, ask a few clarifying questions and propose a solution.
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