Bathroom plastering, even over tiles

What can you have plastered in a bathroom?

A bathroom is not an ordinary room. The difference lies in where the water goes. A ceiling and the wall above the washbasin mainly get damp from steam, while a shower wall gets water directly on the wall every day.

The plaster manufacturer Knauf says that traditional gypsum plasters can be used in a private bathroom without problems, as long as the plaster is not exposed to splashing water. For places with splashing water, such as around the bath, Knauf mentions a water-repellent gypsum plaster.

We do not do decorative finishes such as concrete look. We plaster a bathroom smooth and ready for paint, so that it can be painted afterwards.

For a bathroom ceiling, largely the same choices apply as for any other ceiling. What applies when you have a ceiling plastered therefore applies here too, with extra attention to ventilation.

Can you plaster over tiles?

Yes, plastering over tiles is possible if the tiles are firmly fixed. The advantage is that the tiles do not have to come out. That saves demolition, rubble and the chance of damaging the wall underneath.

Tiles are smooth and barely absorb anything. A plaster layer does not bond to them by itself. That is why such a substrate first gets a pre-treatment that improves adhesion.

Knauf, for example, describes its bonding agent Betokontakt as a pre-treatment for smooth, weakly absorbent or non-absorbent mineral substrates indoors.

At the site survey we tap the tiles. If a tile sounds hollow, it is loose, and a plaster layer on a loose tile eventually comes away with it. Grease and soap residue on the tiles must also go before anything can bond to them.

Plastering over the tiles makes the wall slightly thicker. We allow for that at a junction with a window frame, a door or a mirror, and external corners get a corner bead where needed.

What does bathroom plastering cost?

Plastering in a bathroom has no fixed rate in our price list. Whether plastering goes over tiles, how much pre-treatment the wall needs and where the water goes differs too much from bathroom to bathroom. The price therefore follows after the site survey.

For comparison, the fixed rates for plastering and the items around it are listed below.

Prices exclude VAT. For renovation work on a home over 10 years old, 6% VAT usually applies; otherwise 21%. The VAT rate is stated in the quote.

A bathroom is often a small job in m². That is why the small-job surcharge is in the table: it is in the same price list, and whether it applies to your job, you see in the quote. If you have the bathroom plastered together with other rooms, or if you are having the whole bathroom renovated, everything goes into one quote.

If there is a loose layer or old texture on the ceiling, we remove that plaster first, as a separate item on the quote.

We cover the floor with a floor protection runner. And what plastering costs per m² is therefore not always the whole amount: there may be items alongside it.

Isn’t plaster in a bathroom too damp?

That depends on the spot. On the ceiling and on walls outside the splash zone, a plastered wall is perfectly workable. Knauf states that a temporarily damp climate has no adverse effects, as long as the plaster can dry properly afterwards.

That last point is the key. A bathroom with good extraction or a window that opens dries out again after showering. In a bathroom where the steam lingers, every finish has a hard time, including paint and grout.

Where water hits the wall directly every day, an ordinary paint-ready layer is not the right finish. We look at that at the site survey, and we will also say so if plastering does not suit that spot.

In a bathroom, plaster often makes more sense than wallpaper. If you are torn between plaster or renovation fleece wallpaper, we discuss that at the site survey.

What happens when you have your bathroom plastered?

Having your bathroom plastered by Bouwsector België means one of our own plasterers does the work, such as Bram, who has worked for us for seven years. We have 32 on permanent contracts, as part of 97 in-house tradespeople, together with 40 wallpaperers and 25 painters. No subcontractor comes into your bathroom.

In the phone consultation we ask how your bathroom is laid out, where the shower is and whether there are tiles on the walls. Your free quote follows within 24 hours. If you agree, we come round: we tap the tiles, check where the water goes and how the bathroom ventilates, and take measurements. That way, after the site survey and wall inspection, everything is in black and white.

On the working day we cover the floor, clean the tiles and apply the pre-treatment and the plaster layer. Then the layer has to dry. According to Knauf, a gypsum plaster can be sufficiently dry after about four weeks under good conditions, provided the humid air can leave the room.

Once the layer is dry, a primer goes on first and only then the paint. So do not skip priming after plastering. And if more walls and ceilings need plastering besides the bathroom, we include them in the same quote.

We work throughout Belgium, in Flanders, Brussels and Wallonia. We carry out the site survey at your home anywhere in the country. All rates are on our prices page.