Concealed mixer installation: valve body and trim

What the price depends on

The price comes down to the type of mixer (single-lever or thermostatic), the number of outlets (hand shower, overhead rain shower, bath spout), the wall material, and whether the pipes are already run. A valve body takes longer to set into concrete than into aircrete or a plasterboard stud wall. Labour rates are in the table.

Fixings are usually included in the labour. The mixer and valve body, fittings, pipes, the waterproofing collar and taking away rubble after chasing are paid separately. Tiling is done by a tiler as a separate service.

Price ranges and offers from tradespeople: tap replacement in Warsaw.

What to know before you buy

A concealed mixer comes in two parts. The valve body (often called the box) sits inside the wall, and the trim kit with the handle and cover plate goes on the front. They’re usually sold separately, and not every trim fits every body. Stick to one system from one manufacturer and check they match before anyone starts chasing the wall.

The setting depth is given by the manufacturer and allows for plaster, adhesive and tile; there are usually marks on the body. Set it too deep and you’ll need an extension kit. Too shallow and the cover plate won’t sit flat on the tiles.

A thermostatic valve holds the set temperature even when someone opens a tap in the kitchen. Single-lever is simpler and cheaper. With two or more outlets you need a diverter, which also sits in the body.

Water and safety

Before starting, the water to the whole flat is shut off and the stopcock checked to make sure it holds. The key rule with concealed work: the body and supply pipes are pressure-tested before the wall is closed up. A leak behind tiles gets noticed late, and in a block of flats the neighbours below usually find out first.

How installation works

1. The handle and shower head heights are marked out, and the wall is checked for pipes and cables.
2. A recess is chased for the body, plus channels for the supply pipes.
3. The body goes in level and at the manufacturer’s marked depth, then hot and cold are connected.
4. Pipes are run to the hand shower, rain shower or spout.
5. The system is pressure-tested and every joint checked.
6. A waterproofing collar goes round the body, the wall is closed and the tiler tiles it.
7. After tiling, the trim, handle and shower are fitted and every mode tested.

Common mistakes

• The body set without allowing for the tiles, so the cover plate sticks out or sinks in.
• Hot and cold swapped, so the thermostat works backwards.
• The wall closed up without a pressure test.
• No waterproofing collar, and water runs down the handle into the wall.
• A trim kit from a different range that doesn’t fit the body.
• The protective cover taken off before tiling, letting mortar get into the body.

What to prepare

• The mixer, or at least the exact model of body and trim, with the instructions.
• A sketch: where the handle and shower go, at what height, how many outlets.
• What the wall is made of: brick, concrete, aircrete or plasterboard.
• In a block of flats, check with the administration about noisy work and shutting off the riser if that’s needed.
• Access to the main stopcock.

Frequently asked questions

How to order

Describe in the app which mixer it is, which wall it goes on and what state the bathroom is in, and add photos and the instructions. Handymen near you will send offers with their own price and timing. Compare reviews and pick one; only that person sees your address.

You pay the handyman directly and they issue the invoice. They stand behind their own installation and will fix it if one of their joints leaks or the trim sits crooked. Pipes in the wall laid by someone else and tiles they didn’t lay are not on them.

Fit concealed mixers? Create a tradesperson profile and take bathroom jobs in your town, from the valve body in the wall to the trim. You work for yourself and decide how your business is set up.