What to expect
| Typical duration | 2–4 weeks including waterproofing and tiling |
|---|---|
| Cost band | Figures live in the cost index |
| Permit required | Not usually · new drainage connections may need approval |
| Seasonal constraint | Rentals and hotels in the closed season |
Where the fall can go
In a building where the floor sits on rock or a solid slab, there may be very little depth available for a soil pipe to fall in. That constraint sets the layout before any drawing is made.
- Position the WC as close to the existing stack or connection as possible. Every metre of run costs fall you may not have.
- Raising the floor locally is often the pragmatic answer, checked against door heads, and against the vault curve in a cave room.
- A pumped solution can unlock a position that gravity cannot serve. It is a maintenance item and it is noisy — worth accepting knowingly rather than discovering.
- Wet-room floors need their fall formed in the substrate. A wet room relying on tile lipping will pond.
Extract, especially in cave rooms
A bathroom generates a large amount of moisture in a small space. In a conventional building it leaves through a fan to an external wall. In a cave house the bathroom may be deep in the vault with no external wall anywhere near it.
- Extract sized for the actual room volume and ducted to outside — not into a void, a ceiling space or the vault itself, which simply moves the moisture somewhere it will condense.
- Humidity-controlled operation rather than a light switch, so it runs when there is moisture rather than when someone remembers.
- Make-up air, because an extract fan in a sealed room achieves very little.
- Vapour-open finishes outside the tiled splash zones, so the moisture you do not extract can still leave through the wall rather than collecting behind it. See cave house damp proofing.
Waterproofing and the sequence
Waterproofing goes over the whole wet zone before tiling, and the trades follow a fixed order that cannot be resequenced for convenience: first fix plumbing and electrics, substrate preparation, falls, waterproofing, tiling, second fix, sanitaryware, glass.
Under a single contract this sequence is somebody's job. Where an owner is coordinating separate trades, this is exactly the interface where it goes wrong — a tiler starting before the waterproofing has been tested, or a glass screen measured before the tiles are on. See waterproofing and tiling.
Fittings, water and rentals
- Hard water scales cartridges, aerators, shower heads and glass. Choose fittings whose cartridges are obtainable rather than exotic, because in season a replacement that has to be shipped is a room out of use.
- Glass screens need treating and regular cleaning or they cloud permanently.
- For rentals, favour robust and serviceable over delicate. Wall-hung units on a stone wall need proper fixing, and concealed cisterns need an access panel that is genuinely accessible.
- Water pressure varies with elevation and season. A rain shower that performs beautifully in April may disappoint in August unless the supply has been checked. See plumbing.
Questions people actually ask
Can I move my bathroom to another part of the house?
It depends entirely on whether drainage fall can be achieved to the connection point, and on ventilation. Both are checked before the layout is fixed — moving a bathroom is the single most constrained change in an old building here.
Can I have a bathroom deep inside a cave house?
Yes, with extract sized properly and ducted to outside, and with breathable finishes elsewhere in the room. What does not work is sealing a wet room into a cave and relying on a small fan.
How long does a bathroom take?
Two to four weeks, and the waterproofing and its curing time are a real part of that. A bathroom completed in a week has skipped something.
Why does my shower have poor pressure in summer?
Usually network demand and elevation, sometimes a scaled or undersized booster. It is measurable, and the fix depends on which it is.
Should I use a wet room or a tray?
A wet room needs proper falls in the substrate, which is exactly what is hardest in a shallow floor. Where depth is very limited, a well-detailed tray is often the more reliable answer, and we will say so rather than sell the more expensive option.