You do not need to be a plumber to plan a bathroom, but understanding a few fundamentals will save you money. Most of the expensive surprises in a refit come from water pressure, waste falls and pipe routes, all of which can be checked before anything is ordered.
Your water system decides what you can fit
Combi boiler
Water is heated on demand at mains pressure. There is no cylinder and no loft tank. Pressure is usually good, but flow rate is limited by the boiler output, which is why a large rain head and a second outlet running together can produce disappointing results. A pump cannot legally be fitted to a combi supply.
Gravity fed, cylinder plus loft tank
Common in older Stoke housing. Pressure depends entirely on the height of the tank above the outlet, so a shower on the first floor with a tank just above it may be weak. A shower pump is the usual remedy, and it must be fed correctly with a dedicated take off from the cylinder.
Unvented cylinder
A pressurised cylinder fed from the mains. Excellent pressure and flow at multiple outlets simultaneously, and the best system for a large shower. It must be serviced annually and only worked on by a qualified person.
We measure both static pressure in bar and flow rate in litres per minute at survey, because the two are different and a shower needs both.
Hot and cold pipework
Modern installations run 15mm to most fittings with 22mm on main runs where flow demands it. In older properties you may find imperial half inch copper, or occasionally lead tails at the incoming main, both of which we replace when found. Pipes should be clipped properly, insulated where they run through cold voids, and kept out of the way of any future fixing points such as grab rails. Isolation valves on every fitting are cheap insurance.
Waste, traps and falls
Waste pipes work on gravity alone, so fall is everything. The rule of thumb is 18mm to 20mm of fall per metre of run. Too little and waste sits in the pipe; too much and the water runs away from the solids, which causes blockages. Standard sizes are 32mm for a basin, 40mm for a bath or shower, and 110mm for a toilet.
Each fitting needs a trap holding a water seal, normally 50mm for a bath or basin. Shower traps in a wet room need to be low profile and, crucially, accessible for cleaning, because hair is the number one cause of a slow shower drain. A trap can be emptied by siphonage if the run is long and poorly vented, which is why an air admittance valve is sometimes needed.
The soil stack
Everything ultimately goes to the soil stack, and its position governs your layout more than any other factor. Moving a toilet is expensive not because of the pan but because of the 110mm pipe and the fall it needs. Where the stack is on an outside wall, as it often is in Potteries terraces, connections are straightforward. Where it is boxed inside a corner, opening it up may add a day.
What happens at first fix
- Water off and the old fittings stripped out.
- New hot, cold and waste runs installed to the agreed positions.
- Shower valve body set into the wall at the right depth for the finished tile.
- Everything pressure tested and left under test while walls are closed up.
- Positions photographed before boarding, so future work does not hit a pipe.
Warning signs in an older bathroom
- Slow draining bath, often a partially blocked or badly fallen waste rather than a hair blockage.
- Drain smell, usually a dried out or siphoned trap.
- Banging pipes when a tap closes, water hammer from unrestrained pipework.
- Weak hot flow only, typically scale or a restricted cylinder take off.
- Staining on a ceiling below, which needs investigating before, not after, tiling.
Why in house matters
Plumbing, tiling and electrics all interact. The valve depth depends on the tile thickness, the underfloor heating depends on the floor build up, and the waste route depends on the joists. We carry all those trades in house so the decisions are made by one team rather than negotiated between three.
Book a free survey
We will test your pressure and flow, check the stack and joists, and give you a fixed written price within 24 hours anywhere across Stoke-on-Trent and North Staffordshire.
Common questions
How do I know what water system I have?
A combi boiler with no tanks means mains pressure throughout. A hot water cylinder with a small tank in the loft is a gravity system. A tall insulated cylinder with no loft tank is unvented, which is mains pressure.
How far can a toilet be moved?
Usually up to about 2 to 3 metres with a gravity connection, provided the fall of roughly 18mm to 20mm per metre can be maintained. Beyond that we look at repositioning the stack or using a pumped solution.
Why does my shower lose pressure when a tap runs?
That is typical of an unbalanced gravity system or shared feeds. It is often fixed during a refit by rerunning dedicated supplies in the correct pipe sizes.
What is a trap and why does it matter?
The water filled bend under every fitting that stops drain smells entering the room. It needs at least 50mm of water seal for a bath or basin, and it must not be allowed to dry out or siphon.
Should isolation valves be fitted?
Yes, on every fitting. It means a future tap change does not involve draining the whole system, and it costs very little at first fix.
Do I need a plumber and an electrician?
Both trades are needed in most bathrooms. We carry both in house, so there is one team, one price and no waiting between trades.