Pricing guide
How to price a bathroom renovation
A bathroom is small, but it concentrates plumbing, electrics, waterproofing and tiling into a tight space and a tight programme. Price the sequence and the hidden risk behind the old tiling, not just the fittings on the specification sheet.
Short answer
Price a bathroom renovation by pricing the strip-out and waterproofing first, since they set what every later trade needs. Confirm the position of the soil and waste pipes, the electrical circuit serving a special location near water, and the condition behind the old tiling before committing to a firm figure, and keep tiling, sanitaryware and any structural changes to the floor provisional until they are checked on site.
Quick check
- Confirm the soil pipe and waste run positions before pricing a new sanitaryware layout
- Check the floor structure and joist depth if the toilet or shower position is moving
- Treat electrics in zones near water as Part P notifiable work
- Price tanking and waterproofing to the shower and floor as a fixed step, not an afterthought
- Keep tile and sanitaryware allowances provisional until the client confirms the specification
- Check for asbestos in tile adhesive, backing board or flooring in older properties
- Cost extract ventilation to meet Approved Document F, not just to match the fitting layout
- Allow drying and curing time between waterproofing, screed and tiling in the programme
1. Scope the bathroom on site before pricing it
- Existing pipe positions and the soil stack route
- Floor build-up, joist direction and depth beneath the current floor
- Wall construction, masonry or stud, for fixing and tiling
- Electrical circuit layout and consumer unit capacity
- The extract ventilation route to outside air
- Age of the property and existing tiling, for asbestos risk
2. Labour and trade sequence
A bathroom is small enough that trades overlap quickly if the sequence is not planned. Price each stage in the order it actually runs.
| Stage | What drives the price |
|---|---|
| Strip-out and disposal | Extent of removal, tile adhesive and backing board, and waste volume and access. |
| First fix plumbing and electrics | Whether pipe or cable runs move, and any floor or wall chasing needed. |
| Waterproofing and floor prep | Tanking system, floor levelling, and joist strengthening if boxed in. |
| Tiling and sanitaryware install | Tile size and pattern, finish level, and fitting shower screens or a vanity unit. |
| Second fix and decoration | Sealant, extractor commissioning, snagging, and making good to adjoining rooms. |
3. Materials and where costs blow out
Bespoke shower trays, feature tiles and underfloor heating all carry longer lead times than a standard suite, and a delay to one item can hold the whole job at the second-fix stage.
Client-supplied fittings are a common source of blown budgets: a tap or shower valve bought online does not always match the pipework centres or the fitter's time allowance priced for a standard fitting.
4. What to make provisional, not firm
| Item | Why it stays provisional |
|---|---|
| Floor joist condition | Only visible once the existing boards are lifted. |
| Asbestos in tile adhesive or backing board | Needs a survey before disturbance in a pre-2000 property. |
| Pipework condition behind old tiling | Corrosion or a slow leak is often hidden until strip-out. |
| Structural work for a new shower position | Depends on joist span and whether a load-bearing wall is nearby. |
A waterproofing failure is the most expensive comeback in this trade
Price tanking properly and to the manufacturer's system, rather than trimming it to protect the margin. The cost of a callback once water has tracked into a ceiling below is far higher than the saving.
5. Access, welfare and preliminaries for a bathroom-only job
- Protecting the hallway and stairs used to remove waste and bring in materials
- Temporary washing facilities if this is the client's only bathroom
- Isolating water and electrics safely for each stage of the work
- A skip or bagged waste route sized for a small job
- Dust protection to adjoining bedrooms, especially during strip-out
6. Contingency and margin
A compact bathroom carries more risk per pound of contract value than its size suggests, because so much of the job is hidden behind tiling and boxing until strip-out. Size the contingency to the age and history of the property, not to the floor area.
Worked example
Older properties carry more hidden risk
A 1930s semi with an unrecorded rewire history needs a higher contingency allowance than a house refitted five years ago, even if the new bathroom specification is identical.
7. The underquoting traps specific to bathroom renovations
- Pricing "like for like" tiling when a different tile size needs different floor levelling
- Missing the cost of moving the soil pipe when the toilet position changes
- Underestimating drying and curing time between tanking, screed and tiling, then squeezing the programme
- Assuming the existing extractor duct route is still usable
- Not pricing testing and certification of Part P electrical work into the job
- Treating a "quick refresh" as a straightforward redecoration when the waterproofing beneath it has already failed
8. Present the quote so it compares fairly
Show the strip-out and waterproofing as their own priced stage, since this is where a cheaper quote is most likely to have cut corners. Name the provisional items behind the old tiling separately, so the client can see what the price depends on rather than a single number that looks complete but is not.
Common questions
Do I need a certified electrician for bathroom rewiring?
Yes. Bathrooms are a special location under Approved Document P because of the proximity to water, and the work needs to be carried out and certified by a competent person, or notified to building control.
Can I move a toilet or shower without extra cost?
Moving sanitaryware usually means extending or re-routing the soil pipe and its fall, which is rarely a simple job. Confirm the existing pipe route and available fall before pricing a repositioned layout as a firm figure.
Do I need building regulations approval for a bathroom renovation?
A like-for-like refit generally does not need separate approval, but new electrical circuits, drainage changes or structural work to the floor do. Check the specific scope against GOV.UK's building regulations approval guidance before quoting.
How do I price for hidden problems behind old tiles?
Treat the floor and wall condition as a provisional sum until strip-out confirms it. State what you are checking for, pipe corrosion, joist condition and asbestos, and how the price will be adjusted if a problem is found.
What ventilation does a bathroom need under building regulations?
Approved Document F sets extract ventilation requirements for rooms containing a bath or shower. Confirm the extract rate and duct route needed for the room before pricing the electrical and ventilation work.
Sources and further reading
Primary and authoritative sources used to check this guide.
- Electrical safety: Approved Document PGOV.UK
- Ventilation: Approved Document FGOV.UK
- Approved Document H: drainage and waste disposalLABC
- Building regulations approval: when you need approvalGOV.UK
- AsbestosHealth and Safety Executive
General information for UK residential building work, not legal, tax or electrical safety advice. Building regulations, competent person scheme and drainage requirements depend on the specific property and works. Confirm uncertain treatment with a qualified electrician, building control body or other relevant professional.