Sanitary Fixtures, Fittings and Appliances Installation
Domain focus
This domain tests setting out and installing WCs, wash basins, sinks, showers, urinals, taps, traps and appliances. It covers heights, fixing, waste connections, water connections, sealing and testing.
Core rules
- Set fixture heights from finished floor level and confirm manufacturer's dimensions; keep accessible and level.
- Match waste size to fixture: typically 100 mm for WC, 32–40 mm for basin, 40–50 mm for sink; use the specified trap.
- Maintain the required trap water seal and vent the trap arm; avoid long, shallow trap arms.
- Fit isolation valves and check backflow protection for hose taps and appliances.
- Secure pans and basins without cracking; use correct pan connectors, seals and washers.
- Commission by flushing, running taps, checking for leaks and confirming seal retention.
Worked example
A basin waste is specified at 32 mm. The outlet, trap and waste pipe must all be 32 mm; reducing to 25 mm risks blockage. The reasoning is that the smallest component sets the capacity, so the whole waste path must match the fixture and code.
Traps
Grouting over a trap; missing isolation valves; wrong pan connector offset; over-tightening plastic nuts; no access to trap; sealing a shower waste without fall.