Installation of Concealed Shower Valve (iBox) - Shower Mixer

The body is a metal or plastic housing with inlets for hot and cold water and outlets for the shower. The working parts go in later. This is either a standard lever cartridge or a thermostatic cartridge, plus a diverter if there are two outlets, so you can switch between overhead and hand shower. Many bodies are universal, so the same base takes several types of trim and control. Before installation, check in the manufacturer's technical data sheet that your chosen trim set really fits the body.

Why does this matter so much? Once the body is set into the wall and tiled over, changing to a different system nearly always means taking tiles off.

A plumber usually works in roughly this order:

1. Agree with you on the height of the controls and the position of the shower. Controls usually sit at roughly 100 to 120 cm above the finished floor. The overhead shower goes higher, depending on how tall the people in the household are.
2. Turn off the water and mark the position of the body and the pipe runs on the wall.
3. Cut or chase the recess and channels in the wall, or build the frame in a stud partition or false wall.
4. Set the body level and at the correct depth. The protective cover on the body usually has a marked range showing where the finished tile surface should end.
5. Connect hot on the left and cold on the right, as is standard, and connect the shower outlets.
6. Fix the body and pipes firmly so nothing moves during plastering.
7. Carry out a pressure test in line with the relevant standard and the manufacturer's instructions, before anything is covered up.
8. Fill the chases, fit sealing collars around the body, apply the waterproofing and prepare the wall for tiling.

The visible trim with the lever or thermostat is fitted only after tiling, once the grout and the area around the body are finished.

A lever mixer is simple and easy to repair. A thermostatic valve holds the set temperature even when someone else in the home turns on a tap, and it protects against scalding. Families with small children and older people especially value this. A thermostatic cartridge is more sensitive to limescale, though. In hard water areas, consider filtration or a water softener.

If you want both an overhead shower and a hand shower, you need a body with two outlets and a diverter. Decide early, because adding another outlet to a finished, tiled wall is difficult. In practice, people often regret not having a hand shower fitted as well, as it makes cleaning the shower area much easier.

• A new build or a bathroom stripped back to bare walls is the simplest case, because the wall is open and the pipes can run directly
• A stud partition or false wall makes installation easier, as there is no need to cut into masonry
• Brick is fairly easy to chase, while concrete is hard and the work takes longer
• In blocks of flats with concrete load-bearing walls, deep chases must not be cut without an assessment, so a false wall is often the better choice
• Replacing an old body with a new one is usually harder than it looks, because tiles have to come off and the existing pipework has to be adapted
• More complex setups with several outlets and a diverter mean more joints and longer work

If you live in a flat, arrange with the building management or owners' association in advance to shut off the water on the riser. If the work affects load-bearing walls, ask a structural engineer for advice and check with your local building authority whether anything needs to be notified or approved under local building regulations. Replacing bathroom fittings normally needs no permit, but only the authority can confirm this for your case.

• The body is set too deep or too shallow, so the trim cannot reach the tiles or sticks out from them
• The body is fitted crooked, so the whole faceplate ends up crooked
• Hot and cold are swapped, which causes particular trouble with a thermostatic valve
• The pressure test before closing up the wall is missing or poorly done
• There are no sealing collars or waterproofing around the body, so water gets behind the tiles
• Pipes are not fixed securely, so they bang and vibrate when water flows
• The body and the trim come from different systems and do not fit together

All these mistakes only show up after tiling. That is why it pays to check the work before the wall is covered.

Before and after tiling, check that:

• The pressure test was carried out and no joints leaked during it
• The body is level and its depth is within the range marked on the protective cover
• Sealing collars are fitted around the body and the waterproofing is continuous
• After fitting the trim, hot water comes from the correct side
• The thermostat holds the temperature and the diverter switches reliably between showers
• Nothing bangs or whistles when you turn the water on and off
• After a few days of use, there are no damp patches on the wall or below it
• You have received the technical data sheet and instructions, so it is clear which cartridges and parts belong to the body