Bath Panel Enclosure

A fitted bath stands on adjustable feet, and on its own it is less stable than it looks. When someone gets in and the bath fills with water, it flexes or moves slightly. That movement tears the silicone joint between the bath and the tiles. Water then gets into the gap, and over time you find mould or a damp wall under the bath.

The enclosure has two jobs. The first is practical: the front wall holds the bath in place and stops it shifting. The second is about looks: it hides the feet, the trap and the waste pipes, so the bath blends in with the tiling.

Freestanding baths, the ones that stand in the room like a piece of furniture, are not boxed in. They are designed to look good from every side.

First the bath goes onto its feet, gets levelled and is connected to the waste. Only then does the building start. The fitter checks that the trap does not leak and that the feet are tightened, because later the only way to reach them is through the access hatch.

Next the front wall goes up, plus a side wall if the bath is not set between two walls. The wall is built so that the rim of the bath rests on it or sits just above it, leaving room for the tiles to tuck under the rim later. An opening for the access hatch is left in the wall, usually where the trap is.

Then come primer, waterproofing and tiles. Finally the joint between the bath and the tiles is filled with sanitary silicone. With an acrylic bath, it is a good idea to apply the silicone while the bath is full of water. The bath is loaded and sits slightly lower, so the joint does not tear once the water is drained.

Aircrete blocks

Aerated concrete blocks are the usual choice in practice. They are light, you can cut them with an ordinary handsaw to fit the bath exactly, and they are laid with thin-bed mortar. They also deaden the noise of running water a little. Aircrete soaks up moisture, though, so it always needs primer and a waterproofing coat.

Brick or dense concrete blocks

These are chosen where the wall has to carry more weight, for example when it forms a wide shelf. They are strong and cope better with moisture, but they are heavier and take longer to lay. In a flat it is worth thinking about weight, although one low wall is rarely a problem.

Moisture-resistant board on a frame

Moisture-resistant plasterboard or cement-based tile backer board on a metal stud frame is quick and light, and works well for unusual shapes. It takes knocks less well than masonry, and waterproofing matters even more here. The frame must be fixed firmly to the floor and the wall, otherwise the tiles will crack over time.

Concrete and cast solutions

These turn up in unusual bathrooms where the bath is sunk into a step or forms part of a larger built structure. The result is very solid, but it is hard work, needs formwork and takes longer to cure.

• Shape and position of the bath: a bath in a recess between three walls needs only a front panel, while a corner or asymmetric bath means more cutting and more walls.
• Condition of floor and walls: uneven walls and floors need more levelling before the tiles sit properly.
• Access to the waste: if the trap is in an awkward place or the waste pipe has to be altered, the job takes longer.
• Shelves and ledges: widening the wall into a shelf or step adds work and material.
• Type of access hatch: a magnetic hatch tiled in the same tiles needs far more precision than a simple plastic panel.

If the renovation in a flat touches shared pipework or the soil stack, agree it in advance with the building management or owners' association. Boxing in a bath is ordinary finishing work. If your renovation also includes bigger building changes, check with your local building authority what the local building regulations require.

• The bath is sealed in without an access hatch, so a blocked or leaking trap means breaking tiles
• An acrylic bath is not supported as the manufacturer requires and stands only on its feet, so the base flexes under load
• There is no sealing tape between the bath rim and the wall, and water runs down behind the bath
• Aircrete is tiled without primer and waterproofing, so it soaks up moisture
• The silicone is applied to an empty bath and the joint tears after the first bath
• The wall is built right up to the rim with no allowance for tiles, leaving nowhere to tuck the top row

If you are reasonably handy with tools, you can build a simple front panel yourself. Leave the waste connection to a plumber, or at least have it checked before you start building.

1. Set the bath on its feet, level it with a spirit level and tighten the locking nuts.
2. Connect the trap, fill the bath with water and check the joints for leaks.
3. Fit sealing tape where the bath rim meets the wall, following the manufacturer's instructions.
4. Measure the height under the bath rim and deduct the thickness of the adhesive and tiles.
5. Cut the aircrete blocks to the required height and length.
6. Lay the blocks on the floor with thin-bed mortar, checking level and plumb as you go.
7. Leave an opening for the access hatch where the trap is and fit the hatch frame.
8. Let the mortar cure for the time the manufacturer states.
9. Prime the wall and apply a waterproofing coat, embedding sealing tape in the corners and along the floor joint.
10. Tile the wall and tuck the top row of tiles under the bath rim.
11. Grout, and once the grout has dried, fill the bath with water.
12. Seal the joint between bath and tiles with sanitary silicone and only drain the water once the silicone has cured.

• The bath does not move or creak when you stand in it
• The wall is straight and plumb, and the tiles show no bulges or hollow spots when tapped
• The access hatch opens and you can see the trap through it
• The silicone joint is continuous, free of bubbles and well bonded to both bath and tiles
• No water appears under or behind the bath after a test fill and drain
• The tile joints are even and the top row sits neatly under the bath rim