What the job involves
A wet room is a bathroom where the shower area has no tray or enclosure step. The floor runs continuously into a drain, and the walls and floor are fully waterproofed. Done well, it looks clean and works for people with limited mobility. Done badly, it leaks into the ceiling below or rots the floor over a few years, so most of the skill is in the parts you cannot see once the tiles are on.
A typical conversion covers these stages:
- Strip out. The old bath, shower, tiles and often the floor covering come out so the fitter can see the structure.
- Floor preparation. On a timber floor this usually means checking the joists, strengthening where needed and laying new, rigid boarding. On a concrete floor it may mean cutting a recess for the drain.
- Drainage. A floor-level waste, either a central drain or a linear channel, is connected to the soil or waste pipe. The floor must fall gently towards it, and getting those falls right is a big part of the work.
- Tanking. The floor and the walls in the wet area are sealed with a waterproof system, such as a membrane, tanking boards or a liquid coating, with sealed joints and corners and a sealed drain connection.
- Tiling. Slip-resistant floor tiles go down, usually small enough to follow the falls, with wall tiles to suit.
- Fit and finish. The shower valve, screen, fixed head, toilet, basin, heated towel rail, lighting and extraction are fitted, then the room is sealed and tested.
If pipework, lighting or extraction is altered, the electrical and plumbing work should be done by suitably qualified people. Electrical work in a bathroom is covered by Part P of the Building Regulations. New drainage or structural changes may also need building regulations sign-off, so ask your fitter how they handle this.
What affects the price
No two wet rooms cost the same. These are the things that move the price most:
- Floor type. A timber floor usually needs more work than concrete, because it must be stiffened and boarded to avoid movement that cracks tiles and tanking. A concrete floor may need cutting out for the drain, which is messy and slow.
- Drain position. Using the existing waste position is cheaper than moving it. A new run across joists, or to a distant stack, adds labour and materials.
- Upper floors. A wet room upstairs needs more care with falls and drainage, and the cost of a leak is higher. Ground-floor rooms are often simpler.
- Size and shape of the room. More floor and wall area means more tanking, tile and labour. Awkward shapes, alcoves and sloping ceilings mean more cutting.
- Tanking system. Some systems cost more but are quicker to install or more forgiving. Cheaper ones can be fine if applied carefully.
- Tiles. Large-format tiles are quicker to lay on walls but harder on floors with falls. Mosaics and natural stone take longer and cost more to fit. Natural stone also needs sealing.
- Sanitaryware and fittings. A basic shower valve and standard toilet cost far less than concealed thermostatic valves, wall-hung units and designer brassware. Wall-hung toilets also need a frame and a suitable wall.
- Heating, lighting and extraction. Underfloor heating, a new extractor fan and rewired lighting each add work and may involve an electrician.
- Plumbing changes. Moving the boiler, replacing old pipework or boosting low water pressure can add cost. Any gas work must be done by a Gas Safe registered engineer.
- Hidden problems. Rotten joists, old pipework or uneven walls are often only found once the room is stripped. A good quote explains how these will be handled.
- Access and waste. Top-floor flats, narrow stairs and parking restrictions affect labour and waste removal.
- Your location and the fitter. Rates vary across the UK, and a busy, well-reviewed specialist will often charge more than a general builder.
Ways to keep the cost down
- Keep the drain and toilet where they are. Moving waste pipes is one of the biggest avoidable costs.
- Choose fittings at the middle of the range. Spend on the tanking and the drain, which you cannot easily change later, rather than on brassware.
- Decide everything before work starts. Changing tile or fitting choices midway causes delays and extra labour.
- Supply your own tiles and fittings only if the fitter agrees. Some will not warrant materials they did not supply, and a wrong order can cost more than you save.
- Do the simple jobs yourself. Clearing the room, removing old fittings carefully or decorating afterwards can save labour, but leave tanking and drainage to the professionals.
- Get several itemised quotes. Compare like for like, and compare them against the prices on this page.
- Ask about timing. Some fitters are more flexible in quieter periods, though do not trade quality for a quick start.
What should be included in a quote
A clear quote lists the work in stages rather than giving a single lump sum. Check that it covers:
- [ ] Strip-out and disposal of the old bathroom and rubble
- [ ] Inspection and any repair or strengthening of the floor
- [ ] Type of drain and where it will sit, including any pipework changes
- [ ] Floor falls and the boarding or screed used
- [ ] The named tanking system, covering floor and walls, and how corners, joints and the drain are sealed
- [ ] Tiles, adhesive, grout and trims, stating who supplies them
- [ ] Shower valve, screen, toilet, basin and other fittings, stating who supplies them
- [ ] Electrical work, extraction and lighting, with who will carry it out
- [ ] Heating, such as a towel rail or underfloor heating
- [ ] Making good walls, ceilings and decoration
- [ ] Building regulations notification where it applies
- [ ] A guarantee for the tanking and the workmanship
- [ ] Payment schedule, start date and how long it should take
- [ ] How extra costs from hidden problems will be agreed
Questions to ask a bathroom fitter
- How many wet rooms have you built, and can I see or contact a recent customer?
- Which tanking system do you use, and are you trained to apply it?
- How will you deal with my floor type, and what happens if the joists are not in good condition?
- Where will the waste run, and how will you ensure the falls work properly?
- Will you test the tanking before tiling, for example with a flood test?
- Who does the electrical and plumbing work, and are they registered?
- What guarantee do you give, and is it in writing?
- What is not included in this price?
- How will you protect the rest of the house during the work?
- Who will be on site each day, and will you use subcontractors?
How long it takes and what to expect
A wet room takes longer than a standard bathroom refit, mainly because waterproofing and drainage need time to be done properly. Tanking products and adhesives must cure before the next stage, and rushing this is a common cause of later failure. Expect your fitter to follow the manufacturer's cure times, which may mean a day or two when little seems to be happening.
The work generally runs in this order: strip-out, floor and drain, tanking, tiling, then fitting and finishing. Expect noise and dust at the start, and be prepared to have no usable bathroom for the duration. If it is your only bathroom, plan where you will wash. Sealant also needs time to set, so avoid using the shower until your fitter says it is safe.
Before the final payment, check the drain runs freely, the water drains away without pooling, the seals are neat, and extraction works. Keep any guarantee documents and details of the tanking system used.
Signs a quote is too cheap or too expensive
Too cheap
- No mention of tanking, or vague wording such as "waterproofing included"
- No allowance for floor repairs or levelling
- A price that is far below the others without a clear reason
- No guarantee, or a fitter who will not put anything in writing
- A request for most of the money up front
- Pressure to start immediately
Too expensive
- A single lump sum with no breakdown
- Premium fittings or materials you did not ask for
- Large contingency sums with no explanation
- Charges for work that is not needed, such as moving drains when the existing position would do
- A price far above the others for a similar specification
A fair quote is detailed, explains the risks and tells you what happens if problems turn up. If a price looks out of line, ask the fitter to explain it, and compare it with what other homeowners paid locally.