Venetian Plaster Bathroom Guide: Zones, Systems, Sealing and Care

A Venetian plaster bathroom works, and it works for decades, provided you match the system to the zone. The walls above a basin, around a bath and on the ceiling can take a sealed polished plaster or marmorino. Inside the shower, where water runs down the surface every day, you need Tadelakt or microcement over a proper waterproofing layer, or you need tiles. Get that split right and a plastered bathroom is one of the best rooms in the house: seamless, warm, soft to look at and easy to clean. This is our whole-bathroom guide: zones, systems, sealing, tiles, ventilation, ceilings, care, cost and whether to do it yourself.

Think in zones, not rooms

A bathroom is three environments in one, and the right bathroom plaster depends on which you are looking at.

• Dry walls. The wall behind the door, around the WC, anything above dado height away from the bath. These see steam and the odd splash. Any sealed lime finish is fine here.
• Splash zones. Behind the basin, around a bath that is not used as a shower, the wall a towel rail sits on. Regular wetting, but water does not stand on the surface. Sealed polished plaster works if the sealing is done well; Tadelakt and microcement are safer.
• Wet zones. Inside a shower enclosure, a wet-room wall, the surround where the shower is over the bath. Water runs down the wall and sits at the base. Tadelakt or microcement over tanking, nothing else.

Most bathroom failures we are asked to look at come from putting a splash-zone system into a wet zone. The plaster was never the problem; the specification was.

The systems that work in a polished plaster bathroom

Tadelakt

Tadelakt is the Moroccan lime plaster made for hammams. It is applied thick, compressed with a stone, and treated with olive-oil soap, which reacts with the lime to form a water-repellent surface. It is the only traditional lime finish that belongs inside a shower. It gives a soft, slightly undulating, waxy-looking wall that is entirely seamless. Our Tadelakt 16kg is £134, tinted to your colour, and it is finished with Tadelakt soap (light for pale colours, dark for deep ones). The fuller story is in Tadelakt bathrooms.

Sealed polished plaster

Veneziano, Grassello or marmorino: Venetian polished plaster applied as normal and then protected with a sealer. This is the route to the marble-like polish, and it is ideal for dry walls and good in splash zones. We do not put it inside showers. Grassello in bathrooms explains why and what to use instead.

Microcement

A cement-and-resin coating applied in thin coats over a tanked wall or floor and sealed with a two-part lacquer. Fully waterproof once cured, it goes on floors as well as walls and copes with shower trays and wet-room falls. Its plaster wall texture is closer to concrete than stone, which suits some bathrooms and not others. If you are weighing it against tiling, read microcement vs tiles.

What to avoid

Unsealed lime plaster anywhere in a bathroom. Limewash inside a shower. Any polished plaster on a shower wall, however many coats of sealer are promised. Acrylic “Venetian effect” paints in wet zones, which peel from the back once moisture gets behind them.

Sealing and waterproofing are two different jobs

Waterproofing, or tanking, goes on the substrate before the plaster: a liquid membrane or tanking kit over the boards in wet zones, taped at corners and around pipe penetrations. It stops water reaching the wall behind. We stock a waterproofer (£11) for use with our lime systems in wet areas; tell us your build-up and we will say where it goes.

Sealing goes on top of the finished plaster. For polished plaster and marmorino that means a sealer in two thin coats once the surface has cured. For Tadelakt it means the soap treatment, then periodic re-soaping or a wax. For microcement it means the manufacturer’s lacquer. Sealer on top never makes up for missing tanking underneath.

Can you plaster over tiles?

Yes, and in a bathroom it is often the sensible route, because taking tiles off usually takes the plasterboard with them. The tiles must be sound and firmly bonded: tap them, and remove and fill any that ring hollow. Degrease, fill the grout lines flush so they cannot telegraph through, and prime with a bonding primer, adding a strong adhesion additive to the base coat on a glazed surface. On dry walls and splash zones a marmorino or polished plaster then goes on as normal. In a wet zone, tank over the prepared tiles first and use microcement or Tadelakt on top.

Ventilation

Lime plaster is breathable, which is a genuine advantage in a bathroom: it absorbs and releases moisture and does not feed mould the way a painted plastic film can. But no finish enjoys standing condensation. Fit an extractor that actually moves air, run it on a humidistat or a timer overrun, and keep a trickle vent open.

Ceilings

Plastered bathroom ceilings are usually overlooked. Steam rises, so a ceiling is a splash zone in practice. A sealed marmorino or a matt Tadelakt overhead ties the room together and removes the join line between wall and ceiling that paint always leaves. Avoid high-polish finishes on ceilings, which show every trowel pass under downlights.

Care

Wipe with a soft cloth and warm water. A little Marseille soap for anything stubborn. No bleach, no limescale removers, no abrasive pads. Re-soap Tadelakt now and then; re-seal polished plaster every few years depending on use. How to maintain Venetian plaster has the full routine.

Cost

A plastered bathroom costs more than a painted one and, at the wet-zone end, sits in the same territory as good tiling. Tadelakt is the most labour-intensive finish we do, so a full Tadelakt shower costs more per wall than a sealed polished plaster wall, which in turn costs more than a marmorino dry wall. Material is a small part of the total; preparation and labour are most of it. For bands and what drives them, see polished plaster cost in the UK.

Hire someone or do it yourself?

Dry walls and ceilings in marmorino or sealed polished plaster: a confident DIYer who has practised on boards can do them. Splash zones: possible, with care over the sealing. Wet zones: we would hire. Tadelakt in particular has a rhythm to it, and a shower is not a forgiving place to learn. If you want to understand the material properly first, coat systems, sealing and protection are taught at the bench at the Zavoré Academy. If you want it done, our installation team has finished bathrooms and spas across the UK.

Questions we get asked

Can you use Venetian plaster in a bathroom?

Yes. Sealed polished plaster or marmorino is fine on dry walls, ceilings and splash zones such as behind a basin. The one place it does not belong is inside the shower, where you need Tadelakt or microcement over a tanked wall instead.

Is Venetian plaster good for bathrooms?

It is one of the best finishes for them. Lime is breathable, so it copes with steam and does not feed mould the way a painted plastic film can, and there is no grout to fail or discolour. Kept ventilated and cared for, a lime-plastered bathroom outlasts most tiled ones.

Can Venetian plaster be used in a shower?

Not polished plaster or marmorino. Sealers wear at the wet base of the wall, and once water gets behind a polished finish it will lift. Use Tadelakt or microcement inside the shower and keep the polished plaster for the rest of the room; the two sit together well.

Is Venetian plaster waterproof?

Not on its own. Sealed, polished plaster is water-resistant enough for splash zones and steam. For walls that get running water, Tadelakt or microcement over a tanked substrate is the waterproof route.

Can you plaster over tiles in a bathroom?

Yes, provided the tiles are sound and firmly fixed. Fill the grout lines flush, prime with a bonding primer and an adhesion additive, then plaster as normal on dry and splash walls. In the shower, tank over the tiles first and finish with microcement or Tadelakt.

Where to go next: if you are planning a bathroom and want it done properly, send the room to our installation team with a few photos and the zones you want plastered. If you are doing it yourself, order the Tadelakt, the soap and the waterproofer together, and ask us to check your build-up before you start.