What a kitchen extension costs in West London

Extending a kitchen is the largest single change most people make to a London house, and the cost of it is the thing nobody can get a straight answer about. Here is what actually drives the number, so you can read a quotation and know what you are looking at.

Our own construction rates for a rear extension, a side return and a wraparound are published by specification in the NU Build Cost Calculator. Take your band from there, then use the rest of this to understand what sits inside it and what does not.

What influences the price

Several things move the final figure, and most of them are decided before anybody starts building.

Size and scope

The larger the extension, the higher the cost. A small breakfast nook will cost less than a full-scale kitchen with an open-plan dining area. Think about how much space you want to add and what you want to include in that space.

Materials and finishes

Marble worktops, bespoke cabinetry and high-end appliances all add to the cost. They also last longer than the alternatives, which is the argument for them.

Structural changes

Removing walls, adding beams or altering the roofline all raise the cost. Structural work needs design, calculation and approvals as well as labour.

Design and planning

Hiring a professional designer or architect to create a bespoke kitchen extension can increase upfront costs but often saves money in the long run by avoiding costly mistakes.

Location and site conditions

Building in West London areas like Fulham, Chelsea, or South Kensington can be pricier due to local regulations, access challenges, and labour costs. Your site’s condition, such as soil quality or existing foundations, also affects pricing.

Utilities and services

Extending plumbing, electrical wiring, and heating systems into the new space adds to the budget. Luxury kitchens often require advanced lighting, smart home integration, and high-end appliances, which increase costs.

Breaking the cost down

A quotation should separate these, and if it does not, ask for it to be reissued so it does.

Base construction

The building work itself: foundations, walls, roof, windows and doors. This is what the per-square-foot band in the cost calculator covers, and it is the part that scales with the footprint you are adding.

Interior finishes and fixtures

Flooring, cabinetry, worktops and lighting sit on top of the build rate, and the spread here is enormous. The same extension can take a modest kitchen or one that costs more than the shell around it.

Professional fees

Architects, structural engineers, and project managers typically charge 10-15% of the total project cost. Their expertise ensures your extension is safe, stylish, and compliant with regulations.

Planning and building regulations

Permissions and inspections typically cost between £1,000 and £3,000, and that varies by borough and by the scope of the work.

Contingency

Set aside 10 to 15 per cent for what the opening-up finds. Old wiring and damp are the two that turn up most often.

Putting a figure together

Take your footprint in square feet, multiply it by the band from the cost calculator for the specification you want, then add the fees, the approvals and the contingency above. The kitchen units and appliances sit outside all of it and should be priced separately, because that is the number that varies most from one household to the next.

Managing the budget

Controlling the cost does not mean dropping the standard. Five things that work:

• Separate the must-haves from the nice-to-haves in writing, before you start, and spend where it matters.
• Choose materials that will not date, because the cheapest renovation is the one you do not do again in eight years.
• Use people who have built this before, which is what avoids the expensive mistakes and the waiting.
• Specify for energy efficiency. Insulation, glazing and efficient appliances pay back over the time you own the house.
• Phase it if you need to. Build the structure now and finish it later, rather than cutting the structure.

How NU Projects works

We work on high-end home renovation across West London, including Fulham, Chelsea, South Kensington, Clapham, Battersea and Wandsworth. The design and the build come from one team under one contract, which means the cost plan moves when the drawing does.

Where to start

Knowing what the work costs is the first decision, not the last. Put your own figures against it with the cost calculator, look through the portfolio, then tell us about the house.