Once the shower valve is in place, finish tiling the wall up to the valve. Make sure there's a way to access the valve from the back for future maintenance. The cartridge can be reached from the front.
Before starting, flush the pipes, and turn off the water supply.
1. Install the shower valve: If needed, add battens to the back wall. Position the valve, mark and drill the holes, insert wall plugs if necessary, and secure it with screws.

2. Connect the water supply: Insert 15mm pipes into the inlet connections, tighten nuts, and ensure olives are fitted.
3. Plumb the outlets: Connect 15mm pipework to the top and bottom outlets and connect to chosen products, making sure to fit olives when tightening nuts.
4. Finish the wall: Tile the cavity wall, leaving a gap around the shower valve.
5. Attach the concealing plate and handles: Apply waterproof sealant to the plate's inner edge, slide it onto the valve, and press firmly.
6. Install handles: Put spline adaptors on the valve spindles, attach handles, tighten grub screws, and fit caps.
7. Make rear access: Cut out the rear plasterboard to reach the valve for maintenance. Use removable plasterboard or a panel to cover the access hole.