Kitchens & Bathrooms in London

Kitchen & Bathroom Renovations in London

In most London houses the kitchen and the bathroom are where the old services are. Lead or galvanised water pipes, a cast iron soil stack on the back wall, a gas pipe that’s been extended three times, and a fuse board that pre-dates anyone’s memory. So a refit is mostly about what goes in behind the units and the tiles. The finishes go on last and are the easy bit.

The same trades turn up on both jobs: plumbing work, electrics, some structural work if walls move, plastering, tiling, joinery. That’s why they’re usually priced and planned together.

What’s under the floor and behind the walls

In a Victorian or Edwardian terrace the kitchen is often in the back addition, the narrow wing at the rear. The bathroom is usually above it, or in a converted box room on the half landing. Both sit close to the soil stack, and that is no accident. The stack decides where a WC can go.

Typical finds once things are stripped out:

• lead supply pipe coming in under the front path, common in houses built before about 1970;
• joists notched halfway through by past plumbers, under the bath or the old boiler;
• floorboards rotted around the WC from years of slow leaks;
• old wiring with no earth, or bathroom lights on the same circuit as the landing.

Lead pipe is worth replacing while the floor is up. The section from the boundary stopcock to the house is the owner’s. Thames Water has run schemes to replace their side when the owner replaces theirs, so check with them before the trench is dug.

Drainage decides the layout

Building Regulations Part H covers drainage. The first line of it sets the order of preference:

“An adequate system of drainage shall be provided to carry foul water from appliances within the building to one of the following, listed in order of priority— (a) a public sewer; or where that is not reasonably practicable, (b) a private sewer communicating with a public sewer; or where that is not reasonably practicable, (c) either a septic tank which has an appropriate form of secondary treatment or another wastewater treatment system; or, where that is not reasonably practicable, (d) a cesspool.”

Building Regulations 2010, Schedule 1, Part H1(1)

In London it’s the public sewer every time. What matters on site is the fall. A 40 mm kitchen waste needs a steady drop along its whole run, and Approved Document H gives a range of roughly 18 to 90 mm per metre. Put the sink on an island 4 metres from the outside wall and the pipe either goes in the floor, which means lifting it, or up through the units. A WC needs a 100 mm pipe, and it can’t wander far from the stack. Where it has to, a macerator pump is the fallback. They work, but they’re noisy and they block if anything other than paper goes down them.

The same Part H has an odd line at the end:

“Requirement H1 does not apply to the diversion of water which has been used for personal washing or for the washing of clothes, linen or other articles to collection systems for reuse.”

Building Regulations 2010, Schedule 1, Part H1

That’s the legal opening for greywater systems, where bath and shower water is collected to flush toilets. They’re rare in London houses, but the regulations allow for them.

Much of inner London still drains into Joseph Bazalgette’s sewer network, built after the Great Stink of 1858. Most of it is a combined system, so rainwater and foul water share the same pipes. That’s one reason Thames Water’s approval is needed before building over or near a public sewer, which often runs under the back gardens of terraces.

Kitchens

There’s one requirement in the building regulations that only applies to kitchens, and it’s a single sentence:

“A suitable sink must be provided in any area where food is prepared.”

Building Regulations 2010, Schedule 1, Part G6

It sounds obvious, but it matters with open-plan layouts and utility rooms. The sink has to have hot and cold water, and a drain.

Gas is the other big one. Moving a hob or a boiler is legally work for a Gas Safe registered engineer, no exceptions. Many people now switch to induction, which needs its own cooker circuit, usually a 32 amp radial, from the consumer unit. New circuits are notifiable under Part P, so the work has to be signed off by a registered electrician or by building control. Electrics are usually the second biggest cost after the units.

Extraction should be ducted outside. A recirculating hood only filters grease. Approved Document F gives a cooker hood extract rate of 30 litres a second, or 60 if the fan is elsewhere in the kitchen. In a terrace the duct often runs through a wall cupboard to the side or rear wall, and the route needs to be planned before the units are ordered.

Lead times catch people out. Made-to-order kitchens are commonly 6 to 10 weeks from order. Stone and quartz worktops can’t be cut until the units are fixed in place, because they’re templated on site. Fabrication then takes roughly one to two weeks, and the kitchen can’t be used fully until they’re in.

The usual order is: strip out, first-fix plumbing and electrics, plaster, units, worktop template, worktops, splashback, then second fix and appliances. For ideas on fronts, worktops and lighting, see the modern kitchen trends guide. If the room itself is too small, there’s a separate guide on kitchen extensions in London.

A bit of history: the fitted kitchen with a continuous worktop is usually traced to the Frankfurt Kitchen of 1926, designed by Margarete Schütte-Lihotzky for social housing.

Bathrooms

Water gets into everything in a bathroom. Behind a shower, standard plasterboard and grout aren’t enough. The walls are tanked with a waterproof membrane, or built in cement board, and the corners and pipe entries are sealed with tape before any tile goes on. Wet rooms need the whole floor tanked, with a fall to the drain. On a timber floor that means stiffening the joists first, or tiles crack along the joints.

Ventilation is a legal requirement, not an extra. A bathroom extract fan should do at least 15 litres a second. Electrics in bathrooms follow zones around the bath and shower, with water-resistant ratings for anything near them.

The step-by-step side of planning a bathroom, from budget to fittings, is in our bathroom renovation guide.

The S-bend that stops sewer gas coming back up a toilet was patented by Alexander Cumming, a Scottish watchmaker, in 1775. Thomas Crapper came a century later and didn’t invent the flushing toilet, despite the story.

How long it takes

A full kitchen refit is usually 2 to 4 weeks on site, once the units have arrived. A bathroom is usually 2 to 3 weeks, longer for a wet room because tanking and screeds need drying time. If the kitchen and bathroom are done together, the plumbing and electrics are usually done in one go, which saves time.

Force Builders renovates kitchens and bathrooms in houses and flats across London, including Kensington, Fulham, Putney, Richmond and Finchley.

Kitchen & Bathroom FAQ

How much is this actually going to cost me?

It depends mostly on what’s behind the walls. Keeping the same layout is much cheaper than moving gas, drainage or walls. A fixed price is only possible after someone has looked at the plumbing and electrics on site.

Do I need to hire a separate designer?

Not always. For a like-for-like layout, a measured drawing is enough. For a kitchen moving to a different room or a bathroom moving away from the soil stack, a designer or architect is useful.

How long will I be stuck without a kitchen or shower?

Usually 2 to 4 weeks for a full kitchen and 2 to 3 for a bathroom. A temporary sink and a plug-in hob can often be kept running for part of that.

Is it worth buying my own appliances and tiles?

It can be, but delivery dates and missing parts hold up the job. Whoever orders them needs to check the sizes against the drawings before anything is fitted. For a freestanding bath, a range cooker or an integrated fridge, the exact model should be chosen before first fix. Pipe positions, gas supply and the cabinet sizes depend on it.