By the Bouwsector België team, 97 in-house tradespeople · reviewed by Geert Jan Hendrik, director · updated
Plastering indoors in winter is possible, as long as the room and the wall stay above 5 °C and the damp air can escape. The gypsum manufacturer Knauf specifies a minimum of +5 °C for its gypsum plasters, until at least 48 hours after application, and the wall must not be frozen. Outdoors, we do not work in frost or rain.
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The limit is set out in the manufacturer’s technical data sheets, not in a rule of thumb. For the gypsum plaster MP 75 and the skim coat Multi-Finish, Knauf states the same conditions: the surroundings or the substrate at a minimum of +5 °C and a maximum of +30 °C, and this for at least 48 hours after application.
Those 48 hours are where things often go wrong in winter. It is not only about the working day itself. If the temperature in an unheated house drops below the limit at night, the job no longer complies with the specification, even if it was warm enough during the day.
| Condition | Value | Source |
|---|---|---|
| Temperature of surroundings or substrate when plastering | Minimum +5 °C, maximum +30 °C, until at least 48 hours after application | Knauf MP 75 and Multi-Finish technical data sheets |
| Substrate | Not frozen, before and during application | Knauf MP 75 and Multi-Finish technical data sheets |
| Concrete substrate | At least 3 months old and a maximum of 3% residual moisture | Knauf MP 75 and Multi-Finish technical data sheets |
| Priming after plastering | Substrate and surroundings above 5 °C, humidity a maximum of 85% | Sigmafix Universal product data sheet |
| Moisture in the plaster layer before priming | A maximum of 1% for gypsum-based substrates | Sigmafix Universal product data sheet |
Plaster is mixed with water, and that water has to leave the layer in a controlled way while it hardens. If that water freezes, it expands inside a layer that is not yet strong. The bond to the wall and the strength of the layer suffer as a result.
That is why Knauf specifies that the substrate must not be frozen before and during application. A wall that has stood in a cold house all night can be ice cold while the air already feels pleasant after an hour of heating. It is the wall that counts, not just the air.
Outdoors the risk is greater, because you cannot control the weather. For work on facades we therefore do not work in frost or rain, and we schedule the job for a suitable period.
Yes. Knauf explains that warm air can absorb more moisture than cold air. In a cold room the moisture therefore stays in the layer for longer. On top of that, in winter you cannot ventilate as freely without the house cooling down.
The paint that goes on the wall afterwards also has its own limits if you want to paint walls in winter.
Under good conditions, according to Knauf, gypsum plaster can be dry enough for paint after about four weeks. In winter that is more of a lower limit than a promise. A thin layer dries faster: for a skim coat on a whole home we allow 3 to 5 days for application and drying, less in summer, and we can place heat fans.
The primer also dries more slowly. The Sigmafix Universal product data sheet gives 6 hours until it can be painted over, but that is measured at 23 °C and 50% humidity. At a lower temperature or higher humidity it takes longer. Keep that in mind with plaster drying times, and do not speed up drying by heating alone.
No. Heat makes the air absorb moisture, but if that damp air stays in the room, the moisture condenses on cold spots such as windows and external walls. Knauf describes removing the damp air, by ventilating or with a construction dehumidifier, as at least as important as heating.
The technical data sheets are even more specific. After plastering, any form of moisture build-up, such as condensation, and water forming on the surface must be avoided: with mechanical dehumidification, heating, ventilation, or a combination of these.
In practice that means: heat and regularly open the windows briefly and wide, or run a construction dehumidifier with the windows closed. Heating alone with everything shut moves the moisture to the windows but does not get it out of the house.
A new-build home delivered in winter is often cold and damp. Concrete and cement still release construction moisture, and the heating is sometimes not yet running at full power. For plaster on concrete, Knauf specifies that the substrate must be at least 3 months old and contain a maximum of 3% residual moisture.
If you want to move on quickly in winter, the choice of finish matters. Thick layers ready for painting take a long time to dry.
In new builds we usually work with a skim coat where the wall needs it, with renovation fleece over it. That thin layer dries faster, and the renovation fleece bridges the shrinkage cracks of a home that is still settling. This is how a skim coat in a new build works in your favour, especially in winter.
The reason a new wall gives off moisture for so long is construction moisture: moisture in new-build walls only leaves slowly.
The work is done by one of our 32 plasterers, all permanently employed within a team of 97. Because we plan every step ourselves, we push back the painter or wallpaper hanger if drying takes longer because of the cold, instead of starting regardless.
When you make your request, tell us whether the home is already heated and whether it can be ventilated. Then the free quote you receive within 24 hours already allows for a longer drying time. During the site visit we check whether the room can be heated, how it can be ventilated and how damp the walls are.
The price does not change with the season. Plastering a wall ready for painting costs €22.99 per m² and a ceiling €23.99 per m², always including materials. A plasterer plasters 100 m² a day on average.
Prices exclude VAT. For renovation work on a home over 10 years old, VAT is usually 6%; otherwise it is 21%. The VAT rate is stated in the quote.
Want to know whether your room is suitable for plastering this winter?
Which of the types of interior plaster suits your walls is something we discuss at the consultation. We finish walls and ceilings in the right order, and once it has dried we continue with preparing new plaster for painting.
For its gypsum plasters MP 75 and Multi-Finish, Knauf specifies a minimum of +5 °C for the surroundings or the substrate. That temperature must be maintained until at least 48 hours after application. The substrate must also not be frozen.
Outdoors we do not work in frost or rain, and we schedule facade work for a suitable period. We always carry out exterior plastering on request, after a site visit. We then also discuss when the work fits.
There is a limit there too: Knauf states a maximum of +30 °C for MP 75 and Multi-Finish. Above that limit, application falls outside the manufacturer’s specification. We take that into account as well when we schedule the job.
Only if it does not drop below +5 °C at night either, until at least 48 hours after application. In an unheated home in winter that usually does not work without temporary heating. We discuss this beforehand during the site visit.
Usually yes, because cold air absorbs less moisture. So do not go by the calendar but by the wall: according to the Sigmafix Universal product data sheet, a gypsum-based substrate may contain a maximum of 1% moisture before the primer goes on.
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