Replacing a bath with a walk-in shower: what decides whether it works

Taking a bath out and putting a walk-in shower in its place looks like a straight swap: same corner, same footprint, a tray instead of a tub.

The space is rarely the problem. The drainage is. A bath empties through a waste that sits well above the floor. A low shower tray has almost no height to give away, and the water still has to fall to the soil stack.

Is the space big enough?

Usually, yes. The most common bath in British homes is 1700mm by 700mm, and shower trays are sold in exactly that size as bath replacement trays. The tray goes where the bath was, against the same walls.

Two things to check first:

• Where the door swings. A door can clear the rim of a bath. It cannot clear a glass screen.
• Where the window is. If the bath sits under a window, the shower will be spraying at it.

Tray or level-access floor

A walk-in shower has a tray: a factory-made waterproof base that takes the water to a waste. Low-profile trays sit only a few centimetres above the floor.

A level-access or wet room floor has no tray. The floor itself falls to a drain and the whole area is tanked. It removes the step, and it is a much bigger job underneath. See wet room or walk-in shower. For most bath replacements, a low tray gets most of the look with far less risk.

The waste: the hard part

A shower waste needs a consistent fall all the way to the soil stack. A bath gives you that because its outlet sits high. A tray almost on the floor does not, and the further away the stack, the more height the pipe has to lose.

There are only a few ways to find that height:

• Run the waste between the joists. Upstairs, this depends on which way the joists run. If they run towards the stack, the pipe travels between them. If they run across the route, the pipe has to go through them, and notching or drilling joists is structural work with strict limits.
• Raise the tray on a plinth. Simple and reliable, at the cost of a step.
• Use a pumped waste. A pump lifts the water to the stack. It works, but it is a mechanical part that makes noise, needs power and can fail. Treat it as the last resort.

On a ground floor slab, it may mean cutting a channel into concrete.

Water pressure and shower type

A bath fills slowly and does not care about pressure. A shower does.

A mixer shower blends hot and cold from your existing system and needs adequate pressure on both. On an older gravity-fed system with a tank in the loft, that may mean a pump. With a combi boiler or an unvented cylinder, the pressure is usually there already.

An electric shower heats cold mains water as it passes through, and needs its own dedicated circuit. Under the Building Regulations, installing a new circuit is notifiable work under Part P, as is altering existing circuits in the area around a bath or shower. It needs either a registered electrician who can self-certify, or a building control application. Ask which route your job is taking.

Electrics around the shower

The regulations define a special location around a bath or shower: up to 2.25 metres above the floor (higher if the shower head is higher), and out to 0.6 metres from the edge of the tray.

Without a tray, it reaches further: 1.2 metres from the centre of the shower head. Switch to a trayless floor and a light, shaver socket or towel rail that used to be clear may now be inside it.

Waterproofing

Tiles and grout are not waterproof. A bath gets splashed; a shower soaks the walls around it every day. Those walls need tanking: a membrane behind the tiles, with corners and pipe entries properly detailed. Standard plasterboard that was fine above a bath is not suitable inside a shower.

Ventilation and splash

A shower puts more moisture into the air than a bath. A bathroom needs mechanical extract ducted to outside, at a minimum rate set by the regulations, so check the existing fan is up to it. More in our article on bathroom ventilation.

With no door, the screen does the work, and the head position matters as much as the glass: a head pointing at the open end wets the floor regardless.

Does removing the only bath hurt resale?

There is no universal answer. Families with young children tend to want a bath, and a house without one will put some of them off. Plenty of other buyers never take one.

If it is the only bathroom in a family house, it is a real trade-off. If there is a second bathroom, it matters much less. If someone in the house can no longer safely get into a bath, that settles it.

Older or less mobile users, and grants

Disabled Facilities Grants can pay for adaptations including level-access showers. They are administered by your district council, and in England the grant can be up to £30,000. It is means-tested on household income and savings, though grants for disabled children under 18 are assessed without the parents’ income.

In West Sussex the route starts with an assessment. You contact West Sussex County Council’s occupational therapy team through Adult CarePoint, an occupational therapist assesses what is needed, and their recommendation goes to the district council (Horsham District Council, here), which carries out the means test.

The point that catches people: do not start the work before the grant is approved. Work started early may not be funded at all.

We adapt bathrooms for people with limited mobility, so if that is what this is for, tell us who the room is for and what they find hard. If you are going down the grant route, talk to us before you commit to a design.

What drives the cost

We do not publish prices for this, because the difference between two bath-to-shower jobs is mostly underneath. What moves it:

• The waste route: short and with the joists, or long, across them, or pumped
• Tray or level-access floor: a product, or structural work and tanking
• The shower type, and whether it needs a pump, a hot water upgrade or a new circuit
• How much of the room is touched: one end retiled, or the whole room
• What is under the bath: old leaks and damaged boards are common

What the job involves

In general terms, and in this order:

1. Strip out: bath, panel and surrounding tiles out, back to the structure
2. First fix: waste and supplies to the new positions, floor prepared, any new circuit installed
3. Boarding and tanking: water-resistant board, then the membrane
4. Tray and tiling: tray set level and tested, then tiled
5. Second fix: valve, head, screen, extractor and lighting
6. Sealing and testing: silicone, then a run to check the water leaves as fast as it arrives

If it is your only bathroom, you will be without a shower for most of that.

What to do next

What decides a bath replacement is where the water will go, and that is answered by lifting a floorboard, not by a brochure.

Tell us about the room (which floor it is on and where the soil stack runs) and we will tell you what it will take. Quotations are free, and all our work is guaranteed, with a minimum of 24 months on labour. See also bathroom fitting in Horsham.