Construction dust is finer than household dust and gets everywhere. You cannot air it out — it has to be removed.
After building work there are several different "contaminants" in a room at once:
Each of these needs a different answer, which is exactly why "everything in one go" does not work here.
Construction dust differs from household dust in particle size. It is fine enough to stay airborne for a long time and to get into gaps ordinary dust never reaches — the ventilation duct, the space behind radiators, electrical boxes, the tops of cupboards, light fittings. That is why dust "comes back" for several weeks after the first clean: it has not come back, it is simply settling slowly out of the places nobody wiped.
| Step | When | Why in this order |
|---|---|---|
| Removing building waste | Immediately | It is a constant source of dust |
| Dust removal | After the waste | Dust settles — clean from the top down |
| Ventilation | Over several days | Lets the materials off-gas |
| Surface treatment | After the dust | Does not work on a dusty surface |
| Ozone treatment | Last | Only effective once off-gassing has finished |
The main mistake is using ozone too early. While paint or varnish is still off-gassing, ozone removes what is in the air at that moment, but the off-gassing continues — and the smell is back within days.
There is no single answer, because the timing depends on the materials. The practical guidance is as follows.
The practical approach: tell us which materials were used and how long ago the work finished, and we will suggest a time. If the answer is "wait another two weeks", we will say so — treatment at your expense that will not work is of no interest to us.
We establish what work was done, which materials were used and how long ago.
We check how far the construction dust has spread, including into adjoining rooms.
We treat the surfaces once the dust has been removed.
We treat the grilles and the accessible section of the duct — that is where dust builds up most.
We carry this out once material off-gassing has largely finished.
We air the premises before handing them back.
Ventilation after renovation is a subject of its own. During building work dust is drawn into the duct, and from there it slowly comes back into the room with every movement of air. The grilles and the accessible section of the duct have to be treated, otherwise the room gets cleaned and is dusty again a week later. The same applies to the filters of air conditioning and heat recovery units, if they were running during the work.
To be clear about the boundary: we carry out disinfection, surface treatment and odour removal. Full removal of building waste and deep cleaning are a cleaning company's job, and it is logical to have that done before we arrive.
Fresh plaster, filler and levelling screed release a substantial amount of water into a room over weeks. That is normal — the problem starts if it has nowhere to go.
If the premises are closed up after the work and not ventilated — particularly in winter, when nobody wants to open a window — the moisture condenses on the coldest surfaces: window reveals, external wall corners, behind new furniture. The result is mould on a freshly painted wall within weeks. That is not a question of poor paint but of air exchange.
The other typical mistake is laying a new floor covering over a concrete base that is still damp. The covering seals the moisture in, and after a while fungal growth appears underneath — then the covering has to come up and the work has to be paid for twice. If there is any doubt about whether the base is ready, a moisture reading before laying costs far less than lifting the floor again.
This problem is more common in renovated buildings and new builds than in the older stock, because sealed windows and tightly finished surfaces almost entirely eliminate unplanned air exchange. There, ventilation after renovation is not a recommendation but a necessity.
The season affects it directly. In summer, fresh plaster releases moisture into the room and an open window carries it away. In winter, during the heating season, it cuts both ways: a warm room dries faster, but ventilation happens less often and moisture condenses on the cold surfaces. That is why in renovation finished in winter the first traces of mould usually appear in window reveals and external wall corners, not where the work was done.
Before calling anyone, three steps prevent most of the problems we get called out for afterwards:
Flats from €55 depending on the number of rooms. Ozone treatment €1.20/m², minimum €60. For commercial premises we price by floor area. All prices →
It depends on the materials — a few days for water-based paints, usually several weeks for alkyd paints and varnishes. Tell us what was used and we will suggest a time.
We carry out disinfection and odour removal, and we treat surfaces. Full removal of building waste and deep cleaning are a cleaning company's job.
Plaster, cement and timber dust irritates the airways, particularly for people with asthma or allergies. That is why it is best removed before the premises go back into normal use.
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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