Under the stairs, and other places a toilet can go
The classic position is the under-stairs cupboard in a semi or a terrace. The minimum workable space is about 800 millimetres wide and 1400 deep with the toilet under the higher end of the stairs, so you can stand up straight at the basin. A short-projection toilet, a 300 millimetre corner or wall-hung basin and a sliding or outward-opening door make it work. Other places we have built them: the end of a long hallway, the corner of a utility room, part of an oversized porch, and in a bungalow, a slice of a large bedroom.
The head height rule is simple: if you can stand at the basin without stooping and sit on the toilet without your head touching the stairs, it is usable. Building Regulations do not set a minimum size for a cloakroom, but they do require ventilation and proper drainage.
Drainage: the question that decides everything
A toilet needs a 110 millimetre soil pipe with a fall to the stack or an inspection chamber. If the under-stairs cupboard shares a wall with the outside and the drain run is nearby, we core through the wall and connect, and it is a morning's work. If the only route is across the house, options are a new run under a suspended floor, a boxed run along a wall, or as a last resort a macerator unit, which pumps waste through a small-bore pipe. Macerators work, but they are noisy and they need maintaining, so we treat them as the option when nothing else is possible, not the default.
We also check the water supply (a cold feed is usually easy to find; hot for the basin may need a small under-sink heater if the cylinder is far away) and the ventilation route for a fan.
Fittings that suit a cloakroom
- Short-projection or wall-hung toilets with a slimline concealed cistern.
- Cloakroom basins from 300 to 450 millimetres wide, corner basins, or a small vanity with a cupboard for toilet rolls.
- A mini mixer tap, because full-size taps overhang a small basin and splash.
- A slimline towel rail or a small radiator, so the room is not freezing in January.
- A patterned floor tile or a single bold wall: a cloakroom is the one room where a strong choice works, because nobody is in it for long.
- A humidity-sensing extractor fan, mandatory if there is no window.
Refitting an existing downstairs toilet
Most 1960s to 1990s houses have a downstairs toilet already, often a cold, narrow room with a high-level cistern or an avocado suite. A refit in the same positions takes two or three days: new toilet, new basin and tap, new floor, tiles or panels on the splash areas, paint, a towel rail and a fan. It is a small job that makes a daily difference, and a good one to do before the house goes on the market.