Sanitaryware, Fixtures and Appliance Installation
This domain tests setting out, fixing, connecting and commissioning sanitaryware and appliances: WCs, basins, sinks, baths, showers and urinals. Marks come from correct heights, sound fixings, right-sized wastes and a proper handover to the customer.
Setting out
- WC pan: set the centre line from the soil pipe, seat height about 400 mm, with clear space in front of the pan.
- Washbasin rim 780–800 mm above finished floor; bath rim about 550 mm; shower mixer about 1000–1100 mm; keep fittings level and square to the wall.
- Waste sizes: 32 mm basin, 40 mm sink and bath, 110 mm WC. Every appliance gets its own trap and an isolating valve on the supply.
Fixing and sealing
- Fix into sound masonry with the correct plugs and screws; a pedestal basin still needs a wall fixing.
- Silicone is a seal, not a structural fixing; use it sparingly and tool it before it skins.
- PTFE tape belongs on threaded connections, not on compression olives.
- Flexible connectors only where they remain accessible for inspection.
Commissioning
Flush the pipework, check every joint for leaks, adjust the float valve to shut off about 25 mm below the overflow, confirm the overflow discharges externally, operate taps and mixers, check the fixture is stable, and demonstrate the installation to the customer.
Worked example
A basin trap outlet is 520 mm above floor level and the waste must run 2.4 m to a wall inlet. At 1:40, fall = 2.4 ÷ 40 = 0.06 m = 60 mm, so the inlet must be no higher than 520 − 60 = 460 mm. If the existing inlet is at 500 mm, the fall is only 20 mm (about 1:120) - too flat for a 32 mm waste, so it will clog. Solution: lower the inlet or reposition the basin. Reason: always work backwards from the trap outlet.
Traps
- Cracking a ceramic basin or pan by over-tightening the fixing or connector.
- Omitting the isolating valve, so the fixture cannot be serviced.
- Fitting the wrong waste diameter and blaming the trap for slow drainage.
- Overflow left unconnected or discharging inside the building.
- Fixing the pan before checking it sits level, leaving it rocking.