Ceilings in Wet Rooms: Moisture-Resistant Board and Panels

Choosing ceiling materials for bathrooms, showers and kitchens: moisture-resistant plasterboard, stretch ceilings, PVC and aluminium panels, paint, ventilation and common problems.

The ceilings of bathrooms, shower rooms, kitchens and laundries face steam, warm air and condensation every day. A material that suits an ordinary room will stain, blister, grow mould or sag here within a few years. Choosing a wet-room ceiling starts with the material, but half of success depends on ventilation and detailing.

What stresses a wet-room ceiling

The ceiling is the warmest and most humid zone of the room, because warm steam rises. When steam meets a cold surface, it turns into condensation. Especially in winter, ceilings next to an external wall or roof are colder and collect more condensation.

The result is a familiar set of problems:

• blistering and flaking paint;
• black mould spots in corners and around light fittings;
• cracks at plasterboard joints and sagging boards;
• rust on metal components;
• moisture getting into light fittings.

Most of these problems appear not in the first year but after several seasons. That is why saving money with an ordinary material on a wet-room ceiling can later lead to tearing the ceiling out, mould spreading to the walls and repeat repairs. In a kitchen, greasy vapour adds to this: the ceiling surface must be washable so that the film of grease escaping the extractor can be cleaned off.

Moisture-resistant plasterboard

A plasterboard ceiling can be used in a bathroom, but only with moisture-resistant board. These boards contain special additives and absorb far less moisture than standard board. However, "moisture-resistant" does not mean waterproof: direct water or a long-term leak will damage them too.

A plasterboard ceiling in a wet room has additional requirements. The frame is built from galvanised profiles. Joints are finished with moisture-resistant compound. The surface is primed and coated with washable paint containing anti-mould additives. Directly above a shower, where water splashes, it is safer to consider a different material.

Stretch ceilings

A PVC stretch ceiling is unaffected by moisture and is widely used in bathrooms. Its surface can be wiped and never needs painting. If there is a leak from above, the membrane holds a certain amount of water.

There are points to watch with stretch ceilings too. The void between membrane and slab is closed, so ventilation must be designed properly to prevent condensation building up there. Light fittings must have the appropriate ingress protection rating for a wet room. A special ring is fitted in the membrane in advance for an extractor fan or ventilation grille.

PVC and aluminium panels

Panel ceilings are a practical solution for wet rooms. PVC slats are light, inexpensive and water-resistant, and simple to install. Their drawback is appearance: basic PVC panels often look cheap and can yellow over time.

Aluminium panels and tiles are more durable and look more refined; they are unaffected by moisture and mould and do not rust. They suit bathrooms, pool surrounds and commercial kitchens. Because metal is a cold surface, condensation droplets can form on it in a poorly ventilated room, which again highlights the role of ventilation.

Ventilation matters more than material

Even the best ceiling material will not last in a bathroom without ventilation. The basic rules for wet rooms are:

• check that the natural ventilation duct works, and install a mechanical extractor if needed;
• place the extractor near the shower or bath, in the ceiling or high on the wall;
• leave a gap under or in the door so replacement air can enter;
• wire the extractor to the light or a timer so it keeps running for a while after a shower;
• insulate ceilings adjacent to an external wall or roof to reduce condensation.

Details and common mistakes

The mistakes most often seen in wet-room ceilings are:

• using standard plasterboard and ordinary paint;
• not sealing the junction between ceiling and walls;
• ignoring the protection rating of light fittings;
• closing a ventilation duct behind the ceiling and forgetting about it;
• having no access hatch, so the ceiling must be taken down when a leak occurs.

When ceiling material, lighting and ventilation are planned together, a bathroom stays clean and dry for years.

In bathroom and kitchen renovations Zaferoğlu İnşaat designs the ceiling, ventilation and lighting as one system. For advice on a ceiling that will cope with bathroom steam, contact us.