Cost of Moving a Bathroom Upstairs UK 2026: What You'll Actually Pay

Last reviewed: 13 July 2026

What does the price include?

Relocating a bathroom isn't just disconnecting pipes downstairs and reconnecting them upstairs. UK Building Regulations require proper ventilation, waterproofing, structural support for heavy sanitaryware, and most critically, correct waste pipe falls so everything drains properly. Here's what you're paying for:

First-fix plumbing

Running new hot and cold supply pipes from your cylinder or combi boiler to the new bathroom location, plus new waste pipe routes. £1,200-£2,500 depending on run length.

Waste drainage (soil stack connection)

Connecting to the existing soil stack or installing a new one. New soil stacks cost £800-£1,500; tapping into an existing stack via a new branch costs £400-£800. If gravity drainage won't work, a macerator pump unit adds £600-£1,200 (unit plus fitting).

Structural work

Floor reinforcement for a cast-iron bath, timber treatment for wet areas, and boxing in pipework. £500-£1,500.

Building control approval

New bathrooms require notification under Part G (sanitation) and Part P (electrical). Council building control fees run £300-£500; approved inspector fees are similar.

Second-fix plumbing and finishing

Installing the suite, tiling, flooring, electrics for lights/extractor, and final decoration. £2,000-£4,000 depending on suite quality.

Why does it cost more than a downstairs bathroom?

The main cost driver is waste drainage. Downstairs bathrooms typically sit within a few metres of the soil stack (the large vertical waste pipe that runs to your underground drains). Upstairs bathrooms need much longer pipe runs, and UK Building Regs require a minimum 18mm fall per metre for 100mm soil pipes. If your new bathroom sits 8 metres horizontally from the stack, you need 144mm of vertical drop just to maintain the correct gradient.

Three scenarios:

• New bathroom directly above the old one: Easiest case. You can often tap into the existing soil stack with a short vertical drop. Total project cost £4,500-£6,500.
• New bathroom at the other end of the house: Long pipe runs, potentially routing under floors or boxing in along corridors. May need a new soil stack or external downpipe route. £7,000-£10,000.
• Gravity drainage impossible (e.g. loft conversion bathroom): Install a macerator pump (Saniflo or similar) that grinds waste and pumps it horizontally or even uphill to the stack. Pumps need power, make noise, and require maintenance. £6,000-£8,000 for a basic loft bathroom with macerator.

Can you DIY any of it to save money?

Plumbing and drainage work in habitable rooms must comply with UK Building Regulations, and the work needs to be either done by a registered competent person (e.g. Gas Safe for any gas work, though electric showers are common) or inspected by building control. You can legally do your own plumbing if you notify building control first, but most people hire a qualified plumber because the inspection fees alone run £300-£500, and a plumber's labour for the first-fix is around £800-£1,200 anyway.

What you can DIY:

• Stripping out the old bathroom downstairs (save £200-£400 on demolition labour)
• Tiling and decorating the new bathroom once the plumber has second-fixed (save £600-£1,200)
• Sourcing your own sanitaryware instead of using the plumber's merchant account (net saving maybe £200-£300 once you account for your time and delivery charges)

You cannot DIY the electrical work if it's in a bathroom (notifiable under Part P) unless you're a registered electrician. Extractor fans, shaver sockets, and electric showers all fall under this.

Do you need planning permission?

No, for internal alterations like moving a bathroom upstairs, planning permission is not required. You do need Building Regulations approval, which is separate. Planning controls what your house looks like from outside and how it's used; building control ensures it's built safely.

The exception: if your house is listed or in a conservation area, internal structural changes might need listed building consent. Check with your local planning authority.

What about the old bathroom downstairs?

Budget £800-£1,500 to make good the downstairs room once the bathroom is stripped out. You'll need to cap off or remove the old waste pipes, patch walls, and probably re-plaster and redecorate. Some people convert the old bathroom into a utility room (keeping the plumbing for a washing machine) or a downstairs WC (toilet and basin only, much simpler waste routing than a full bathroom).

How long does it take?

A straightforward upstairs bathroom relocation takes 2-3 weeks from first-fix to usable:

• Week 1: Strip out old bathroom, run new supply and waste pipes, building control first inspection
• Week 2: Second-fix plumbing (install suite), electrics, tiling, building control final inspection
• Week 3 (if needed): Snagging, decoration, making good downstairs

You'll be without a bathroom for most of this period unless you have a second one. Some households arrange to use a neighbour's or family member's facilities; others pay for a temporary site toilet (£80-£120 per week hire).

Is a macerator pump worth considering?

Macerator units (Saniflo is the best-known brand) grind solid waste and pump it through small-bore (32mm) pipes to the soil stack. They cost £300-£600 for the unit plus £300-£600 to fit, so they're cheaper than routing large-bore gravity drainage across long distances or installing a new soil stack.

Downsides:

• They make noise when flushing (a grinding/pumping sound for 15-30 seconds)
• They need a power supply, so if the electrics fail, the toilet doesn't work
• They can block if you put anything other than toilet paper down (wet wipes, sanitary products, and excessive paper all cause problems)
• Lifespan is around 10-15 years before the pump motor needs replacing

They're most commonly used in loft conversions, where running gravity drainage is difficult, or in basements where waste needs to be pumped up to ground-level drains.

How much does it cost to add a new soil stack?

If your new upstairs bathroom can't practically connect to the existing soil stack, you can install a new one. Costs:

• Internal soil stack (boxed in): £1,200-£1,800 including building the boxing and fire-stopping where it passes through floors
• External soil stack (down the outside wall): £800-£1,200, easier to install but needs a hole through the external wall and matching your render/brickwork

Both need a new connection to your underground drainage, which might mean digging up part of your garden or driveway to lay a new drain run to the main sewer or septic tank. That adds another £600-£1,500 depending on distance.

What are the typical quotes for this job?

Get at least three quotes from plumbers who've done bathroom relocations before (not just suite swaps). Typical all-in quotes for moving a bathroom upstairs in 2026:

• Basic relocation over existing bathroom: £4,500-£6,500
• Long-distance relocation (10m+ pipe run): £7,000-£10,000
• Loft conversion bathroom with macerator: £6,000-£8,000
• Full relocation with new external soil stack: £9,000-£12,000

These assume you're using mid-range sanitaryware (£800-£1,500 for suite, taps, and shower). High-end suites with walk-in showers and underfloor heating can push the total to £15,000+.