A basement is the coldest room in a building and the only one bordering the ground — so damp there is the default state.
A basement borders the ground and is colder than the rest of the building. That means two permanent sources of moisture: capillary moisture rising from the foundations, and condensation forming when warmer air meets the cold walls.
More on the causes and the correct airing regime on the page about mould in basements. This page is about the basement as a site to be treated.
A basement should not be aired on a warm, humid day — that brings moisture in rather than taking it out.
Counter-intuitively, an open basement window in summer usually makes things worse. Warm outside air holds far more water vapour than the cool basement air; once inside, meeting a wall colder than the dew point, it condenses on it. Airing makes sense in cool, dry weather — in autumn, in winter and early in the morning. In some basements that alone is enough to change the situation noticeably.
Before treatment it is worth understanding exactly what you are dealing with, because the answers differ.
A practical example. In the basement of a block of flats the smell is strongest at one end, and that is exactly where there is dew on the ceiling and the pipes. If there is a heating substation or uninsulated hot water pipes nearby, that is a condensation case rather than moisture from the ground — and the first step is insulating the pipes, not treatment.
In blocks of flats the basement is common property, and its condition affects the whole building: smells travel through the stairwell and the ventilation into the flats, particularly on the lower floors.
This kind of work is usually ordered by the property manager or the residents' representative. After an inspection we prepare a quote setting out the scope of work, which can be submitted for consideration.
| Situation | Who usually orders |
|---|---|
| Basement in a private house | The owner |
| Shared basement in a block of flats | Property manager or residents' representative |
| An individual basement storage unit | The flat owner |
| Basement of a commercial building | The company |
The practical difficulty in shared basements is that the space is divided into storage units with different owners, and not all of them are available on the same day. So before the work we agree whether we treat only the common part — corridors, plant rooms, walls and ceilings — or the inside of the units too, which requires each owner's access and advance notice.
Another common basement situation is a smell that is not a mould smell. If it is distinctly a sewage smell, the first thing to check is the floor gullies and the drains used least often — a dried-out trap is the commonest answer and needs no treatment at all. If there has been a sewage leak, that is an incident with its own treatment procedure and its own price.
What is stored in a basement is often part of the problem rather than just its victim. Cardboard boxes, paper, textiles, timber shelving and old furniture absorb moisture and act as a store for it: even once the room has dried out, they go on releasing moisture back into the air for a long time and keep the smell going. They also usually stand tight against the wall, where the air does not move.
Seasonality in basements is as pronounced as in garages. The greatest risk of condensation is not mid-winter, when everything is uniformly cold, but in the transitional periods: May and June, when it is already warm and humid outside but the basement walls have not yet warmed up, and September to October, when warm air meets an already cooled structure.
Those are exactly the months when people notice that stored things are damp and patches have appeared on the walls. Treatment is best planned after that period, once the space has dried out, rather than in the middle of it while condensation is forming daily.
We measure the moisture and establish whether it comes from the ground or from condensation.
We settle whether we treat only the common part or the storage units too.
We recommend taking out cardboard and textiles — they feed the fungus.
Where needed, we remove the layer of mould before treatment.
We treat walls, ceilings and structures.
In wider cases we treat the whole space with a fogging machine.
The airing regime and, where needed, a note about damp-proofing.
What most often goes wrong in basements: treatment is ordered but the stored items stay where they are, and a month later the smell is back; or treatment is taken to be a solution to damp when the cause is in the structure. We flag both before the work, not after.
We do not lay damp-proofing or drainage, insulate pipes or install ventilation. We do not clear out stored items or empty the basement — the owner or the property manager does that to our instructions. We do not assess structural condition. And we do not claim treatment removes damp: it clears the fungus and the smell, but the cause stays as it is until it is dealt with.
Basement treatment from €1.20/m², minimum order from €80. For larger shared basements — €0.90/m² (100–300 m²) or €0.70/m² (300–1000 m²).
Treatment clears the fungus and the smell. It does not remove damp — if the cause is capillary moisture, the answer is damp-proofing, and we say so openly.
We recommend removing cardboard boxes, paper and textiles — they hold moisture and feed the fungus. The rest can usually stay.
It is normally organised by the property manager. After an inspection we prepare a quote that can be submitted for consideration.
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.
Thank you! We will contact you on the phone number you provided shortly.
