Cloakroom installation

Answer the drainage question first

Everything else about a cloakroom – the suite, the tiling, the basin, the door – is straightforward. Drainage is the variable, and it can change the job substantially.

1. Find the soil stackInternal or external, and where it runs. That is the destination for WC waste.
2. Measure the horizontal distanceFrom the proposed WC position to the stack.
3. Check the available fallA soil branch needs a consistent gradient within defined limits. Too shallow and solids are left behind; too steep and water runs away from them, which is equally bad.
4. Check the floor constructionSuspended timber gives you a void to run in, and you have to work with the joists rather than through them. Solid concrete means either a shallow pan arrangement, raising the floor, or cutting – which is a much bigger job.
5. Establish the drain invert levelIf the connection point is higher than the WC outlet route allows, gravity is not available.
6. Identify the water supply routeCold to the cistern and the basin; hot to the basin if you want it, which is not mandatory.
7. Check ventilationA cloakroom with no openable window needs mechanical extract, usually with an overrun.

Gravity or pumped

Gravity is better where it is achievable. Where it would mean cutting a solid floor or running a long shallow branch that will not work properly, a macerator is a legitimate answer and it is what makes some cloakrooms possible at all – see macerators and pumped WCs.

Fitting a usable room into a small space

Cloakrooms are small, and the difference between one that works and one that irritates is a few decisions.

• Door swing. An inward-opening door eats the floor area you need to stand in. Outward, sliding or a pocket door frequently transforms a tight cloakroom. Also consider whether somebody who has been taken ill could be reached if the door opens inward – that is a genuine argument for outward.
• Short projection pan, which gives back valuable floor depth against a standard one.
• Wall-hung or back-to-wall, with a concealed cistern in a frame. Neater, easier to clean, and the frame takes depth from the room – so it suits a room with length rather than width.
• Corner basin or a small semi-recessed basin. Cloakroom basins do not need to be large; they need to be usable without splashing the wall.
• Tap position. A tall monobloc on a small basin sends water everywhere. A short spout suits it better.
• Cold-only basin is permitted and it saves running a hot pipe a long way for a tap that will be run for fifteen seconds. Whether you want it is a comfort question rather than a regulatory one.
• Light and extract on the same switch with a timer overrun, where there is no window.
• Somewhere for a toilet roll and a hand towel that is not an afterthought drilled into new tiling.

Things easy to get wrong

1. Cutting joists to run the soil pipe. Notching and drilling are limited for structural reasons, and a soil pipe is large. The pipe route has to work with the joists – which sometimes means the WC moves.
2. Inadequate fall, which produces a WC that needs two flushes and blocks regularly. It cannot be corrected afterwards without redoing the branch.
3. Excessive fall, which leaves solids behind as the water outruns them. Equally a problem and less intuitive.
4. No isolation valves, so the whole house has to be drained to change a tap washer.
5. A concealed cistern with no access, which is exactly the same mistake as a macerator with no access panel and produces exactly the same outcome.
6. No extract, in a windowless room, which is a Building Regulations requirement and also a matter of simply being habitable.
7. Forgetting the basin waste, which also needs a route and a trap, and which is easier to solve than the WC but is not free.
8. Tiling before testing. Everything gets filled, pressure tested and left before anything is closed up.

Notification and the practical bits

Adding a WC is generally notifiable work under Building Regulations – the drainage connection, the ventilation and any structural alteration are the reasons. That is normally handled by a building notice or a full plans application through the local authority, and it is straightforward. Electrical work in a bathroom or cloakroom also has its own requirements.

Sequence that keeps a cloakroom job short:

• Confirm drainage before anything else, because it determines the layout and the budget.
• Agree the exact positions on site, with the suite present, not from a drawing.
• First fix – waste, supplies, electrics, extract ducting.
• Test and leave under pressure before closing anything up.
• Boarding, tiling, decoration.
• Second fix – suite, basin, taps, extract, accessories.
• Commission and demonstrate – where the isolation valves are, how the extract overrun works.

See also bathroom renovations and bathroom layouts and soil pipes.