Advice · 4 min read · Updated 6 November 2026
Plasterboard in bathrooms and showers: boards, tiles and weight limits
Choosing the background by zone
| Area | Usual background |
|---|---|
| Bathroom walls away from water, painted | Moisture-resistant plasterboard, taped and jointed or skimmed |
| Bathroom ceiling | Moisture-resistant plasterboard, with good extraction |
| Walls behind a bath, tiled | Moisture-resistant board, with tanking at the splash zone |
| Shower enclosure, tiled | Cement board or foam tile backer board, or board fully tanked |
| Wet room walls and floor | A complete tanking or tile backer system |
| Kitchen splashback | Standard or moisture-resistant board, depending on exposure |
Tile weight limits
Tile weight is often overlooked. Tile and adhesive suppliers commonly quote these approximate maximums, including tile, adhesive and grout:
| Background | Typical maximum load |
|---|---|
| Gypsum plaster, including skimmed walls | About 20 kg per m² |
| Plasterboard, not skimmed | About 32 kg per m² |
| Fibre cement backer board | Up to about 200 kg per m², depending on product |
| Foam-cored tile backer board | Often up to about 120 kg per m², depending on product |
A large-format porcelain tile with adhesive can easily exceed 20 kg per m², which is why tilers often ask for bathroom walls to be left as plasterboard without a skim. Always check the figures for the specific board and adhesive you are using.
Skim or no skim in a bathroom?
For walls that will be tiled, leaving boards unskimmed usually gives a higher weight limit and a better bond, as long as the board surface is primed as the adhesive manufacturer recommends. Walls that will only be painted can be skimmed or taped and jointed. Mixing the two in one room is common: tile backer in the shower, moisture-resistant board elsewhere.
Painted bathroom walls and ceilings benefit from a skim or a well-finished tape and joint, followed by a mist coat and a paint designed for kitchens and bathrooms. These paints resist moisture and are easier to wipe clean, which helps keep mould at bay around showers and windows.
Detailing that stops leaks
- Fix boards to studs at the closer spacing recommended for tiled walls
- Use the board manufacturer's screws and seal cut edges where advised
- Tank internal corners, board joints and pipe penetrations in the shower zone
- Seal around bath and shower trays with a flexible joint, not grout
- Keep the bottom edge of board clear of the floor in wet areas
- Fit noggins for shower valves, grab rails, basins and wall-hung toilets before boarding
Ventilation matters as much as board
Even the right board will suffer in a bathroom that stays wet. Building regulations expect bathrooms in new work to have mechanical extraction, and a good extractor fan, ideally with a humidistat or overrun timer, does more to prevent mould on ceilings than any board choice. Leaving the fan to run after a shower and keeping a gap under the door helps air move through.
Where a bathroom has no window, or the window is rarely opened, extraction becomes even more important. Ducting should run as short and straight as possible to the outside, with insulation where it passes through a cold loft, so condensation does not run back down into the fan or drip onto the new ceiling.
Common mistakes
- Using standard plasterboard in a shower because it will be tiled anyway
- Tiling heavy porcelain onto a skimmed wall
- Skipping tanking at the shower tray and corners
- Fitting boards without solid fixings for heavy wall-hung fittings
- Leaving the extractor fan out of the plan
Planning a bathroom refit around the boarding
In a bathroom refit, boarding happens after the old suite is stripped out and the first fix is done, and before tanking and tiling. The order matters, because once the boards are up, moving a pipe or adding a noggin means cutting them out again.
- Strip out the old suite, tiles and damaged board
- Check the studs and floor, and repair any rot or leaks
- Plumber and electrician complete first fix, including extractor fan and shaver socket
- Fit noggins for basin, toilet frame, towel rail, valves and grab rails
- Fix moisture-resistant board and backer board to the agreed layout
- Tank the shower zone and wet areas
- Tile, then second fix plumbing and electrics
Photograph each wall before boarding, showing pipe and cable runs. It makes future repairs and fixings far easier.
Where a bathroom is on a timber floor, the floor also needs to be stiff enough for tiles. Overboarding with a tile backer board or plywood, fixed at close centres, reduces movement that can crack grout and tiles. Wet room floors need a proper former and fall to the drain, so they are usually planned as a complete system from one manufacturer.
Frequently asked questions
Is green plasterboard waterproof?
No. Moisture-resistant plasterboard, often green or blue depending on the brand, resists humidity and occasional splashes better than standard board, but it is not waterproof. In showers and wet rooms that are tiled directly, use a cement or tile backer board, or tank the board with a waterproofing system designed for that purpose.
Can I tile directly onto plasterboard?
Yes, provided it is the right board, firmly fixed, primed if the adhesive maker requires it, and the total weight of tiles and adhesive stays within limits, commonly about 32 kg per square metre for unskimmed plasterboard. In showers and other wet zones, waterproofing is also needed. Heavy natural stone or large porcelain usually calls for a backer board instead.
Should a bathroom ceiling use moisture-resistant board?
It is a sensible choice, because warm moist air rises and condenses on the ceiling. Moisture-resistant board copes better with that humidity than standard board. It works best alongside a good extractor fan, a mist coat and a suitable bathroom paint. Without ventilation, any ceiling is likely to show mould sooner or later.
bathrooms tiling moisture-resistant board wet rooms
