Shower installation: what is involved in fitting a new shower

Combi boilers and unvented cylinders supply mains-pressure hot water, which suits thermostatic mixer showers. Gravity systems with a loft tank give lower pressure, so a pumped shower or a power shower may be needed. Electric showers heat cold mains water themselves and work with any system, but need their own electrical supply from a qualified electrician.

Our shower types guide compares these in more detail, and our low water pressure guide explains what to do if pressure is weak.

The shower needs a route for hot and cold supplies and a waste pipe with enough fall to reach the soil stack or drain. Over a bath this is usually simple. In a new corner or alcove it can mean lifting floorboards or boxing in pipes.

Concealed valves, where only the control shows on the wall, need the pipework chased into or built behind the wall before tiling. Exposed bar valves are simpler to fit to an existing wall.

Walls around a shower take far more water than anywhere else in the house. Plasterboard should be replaced or protected with a suitable backer board, and the shower area waterproofed before tiling.

Tiles and grout alone are not waterproof. Skipping this step is the most common reason a shower leaks through to the ceiling below. Our tanking guide explains how it is done.

The tray is fitted level on a solid base and connected to the waste. The valve and riser or head go in, the walls are tiled and grouted, then the screen or door is fitted and every joint is sealed with silicone.

Before handover the shower is run and checked for leaks at the valve, waste and screen seals, and you are shown how to use and clean it.

If you already have a shower and want a new one in the same place, the job is often simpler, but it is still worth checking the tray, seals and wall behind. A new shower on an old, leaking tray will not stay dry for long. Our shower replacement guide covers when a like-for-like swap is enough.

A tray bedded on a few blobs of adhesive instead of a full, solid base, which lets it flex and break the seal. A waste pipe with too little fall, which drains slowly and smells. Silicone applied over dirty or wet surfaces. Screens fixed into grout lines rather than tile. Each is easy to avoid at installation and expensive to fix once the walls are finished.