Refitting a bathroom: the sensible order of work

A bathroom refit is several trades working in a small room, one after another. Most of the problems people run into, such as tiles that have to come off again, a shower valve set at the wrong depth or a waste with no access, come from doing the stages in the wrong order. This guide sets out the usual sequence for a UK bathroom and who normally does what. It is not a fitting manual. Every product's instructions, and the people you hire, have the final say.

Before anything comes out: plan

Decide the layout first, because almost every later decision hangs on it.

• The toilet is the least flexible item. It has to reach the soil pipe, which is a large pipe, so moving a toilet far from where it is now can mean major work. Ask a plumber early.
• The shower decides a lot: whether you want an electric or mixer shower (see electric vs mixer showers), whether your hot water system suits it, and whether you want a tray or a level-access wet floor. Our shower trays and wastes guide covers the tray side.
• The bath needs space under and around it for its waste and trap, and a panel you can get behind later. See bath panels and traps.
• Ventilation, lighting and heating. An extractor fan, lights and an electric or dual fuel towel rail all involve electrical work.

Then check the rules. GOV.UK's when you need building regulations approval page lists installing a bathroom that will involve plumbing, and changing electrics near a bath or shower, among the alteration projects that might need approval. Trades registered with a competent person scheme can self-certify the work they are registered for. If you are unsure, ask the trades you hire, or your local building control body, before work starts. Scotland and Northern Ireland have their own systems. Flats may also need the freeholder's or landlord's consent.

The usual order of work

1. Book the trades and order the products

Have the main items (bath or tray, toilet, basin, taps, shower valve, tiles) chosen before the plumber's first visit. Concealed valves, wall-hung toilets and some wastes need specific pipe positions and depths that only make sense once the product is known.

2. Make safe and strip out

Water to the room is isolated, and anything electrical in the way is made safe by an electrician. Then the old suite, tiles and boards come out. This is the stage to find rotten floorboards, old leaks and pipes in odd places. If the strip-out uncovers a gas pipe or the boiler is in the room, nobody but a Gas Safe registered engineer should touch it. See when to call a Gas Safe engineer.

3. Repairs and floor

Joists, subfloor and any structural repairs come next, along with any new noggins or supports for wall-hung items, heavy basins, a towel rail or a stone resin tray.

4. First fix: pipes, wastes and cables

First fix means everything that will end up hidden. The plumber runs the hot and cold supplies, the wastes and the soil connection to the new positions, fits concealed valves and cisterns, and pressure tests the pipework before it is covered. The electrician runs cables for the fan, lights and any towel rail or shaver socket. Isolation valves to each appliance are worth asking for now; see isolation valves.

Photograph the walls and floor at this stage, with a tape measure in shot. It will save you drilling into a pipe years from now.

5. Boarding and wet-area preparation

Walls and floors in the wet zones are boarded with suitable backer boards, and areas that will get regularly soaked, such as shower enclosures and wet floors, are usually tanked: given a waterproof membrane or system before tiling. The product system's instructions decide the details. Tiles and grout on their own are not waterproof. See wet rooms and tanking.

6. Bath and shower tray

The bath and shower tray usually go in before the wall tiles, so the tiles can sit over their upstands or edges and shed water into them rather than behind them. Wastes are connected and tested at this point, while they are still easy to reach.

7. Tiling

The tiler works around the fixed items, leaving the gaps where sealant will go. Tile trims, and the line where the floor meets the walls, are agreed now.

8. Second fix

Toilet, basin, taps, shower valve trims, shower screen, towel rail and electrical fittings go on. The plumber fills, checks and tests everything, including running wastes and checking for drips under each one. The electrician tests and certifies their work.

9. Sealing and finishing

Joints between the bath, tray and basin and the tiles are sealed with sanitary silicone once the grout is cured. Our sealant and silicone guide explains why this is the last job, not a fix for anything underneath.

Who does what

• Plumber: layout advice, first-fix pipework and wastes, bath and tray installation, second fix and testing. See hiring a plumber.
• Electrician: anything electrical in the room. A qualified electrician registered with a competent person scheme can certify the work.
• Tiler: boarding and tanking are often done by the tiler, sometimes by the fitter. Agree who is responsible.
• Gas Safe registered engineer: only if gas pipework or the boiler is affected.
• Bathroom fitter: some firms manage all of the above with their own trades. Ask who will actually do each stage and who signs off the notifiable parts.

How long does a bathroom refit take?

It depends on the size, the condition of what is behind the walls and how many trades are involved. Each trade usually needs more than one visit, and tile adhesive, grout and sealant all need curing time between stages. Ask for a written schedule rather than a single total.

Can I tile before the plumber has finished?

Not usually. First-fix pipework and the bath or tray should be in and tested first, otherwise tiles may have to come off to fix a leak or move a pipe.

Do I have to use one firm for the whole job?

No. Some people hire separate trades and manage the order themselves. It can work well, but you then carry the job of making sure each stage is finished and tested before the next one covers it.