London kitchen extension companies: 10 checks

Why the contractor decides the outcome

In London the kitchen is rarely just a kitchen. It is the entertaining space, the room the ground floor is planned around, and often the most valuable square footage in the house.

A kitchen extension done well adds value, daylight and flow. Done badly it is a costly compromise that is expensive to unpick. With planning constraints, structural complexity, party wall matters and conservation restrictions across Chelsea, Kensington, Fulham, Hampstead and prime central London, who builds it matters as much as what is drawn.

There is no reliable ranking of kitchen extension companies, because nobody audits the projects. What follows is the set of checks that tells one firm from another.

What a prime extension contractor needs

At the premium end, a kitchen extension is more than removing a wall and fitting bi-fold doors. Look for:

• Structural engineering judgement, not just a steel supplier
• Experience with load paths and steel reconfiguration
• Planning and conservation knowledge in your borough
• Underpinning capability where the levels demand it
• Glazing, roofing and insulation detailed as one system
• Finish standards that match the rest of the house
• Commercial and programme control
• Senior people who stay on the project

Ten checks before you appoint

1. Comparable completed extensions

Ask for finished work on the same kind of house, with the same kind of opening. A garden room on a detached house tells you little about a side return on a Victorian terrace. Review the NU Projects portfolio.

2. Who designs the structure

Removing the back wall of a house is a structural job. Ask who designs the steel, who calculates the load paths, who checks it, and how the temporary support works while the wall is out.

3. The planning route for your actual address

Some extensions are permitted development and some are not. Previous extensions, conservation status and an Article 4 direction all change the answer. Ask for it checked against the property, not the street.

4. Party wall notices

Building up to or along a boundary engages the Party Wall etc. Act. Ask who appoints the surveyor and when notices go out, because late notices are the most common cause of delay on a terrace.

5. Where the daylight comes from

A badly glazed extension makes the existing kitchen darker by burying the original back window under a new roof. Ask for the daylight strategy, not the glazing schedule. Where the glass goes matters more than how much there is.

6. Drainage and levels

A level threshold to the garden, a new roof and a new floor all have to work with the existing drainage. Ask where the falls run, where the manholes end up and who is responsible if a public sewer is close.

7. Services in the new space

Underfloor heating, extraction, lighting circuits, power for the appliances, data and controls all have to be in before the screed and the plaster. Ask when the MEP design is done and by whom.

8. Glazing lead times

Large sliding or pocket doors are measured in months, and they are usually the item that decides the finish date. Ask for the lead time in writing and what happens if it moves.

9. How the kitchen itself is coordinated

The kitchen is usually a separate supplier. Ask who coordinates its drawings with the structure, the services and the floor build-up, and who is responsible if a unit does not fit.

10. What is in the price, and what is not

Separate the base build from the glazing, the kitchen, the appliances, the joinery, the lighting, the finishes, the external work, the fees, the statutory costs, contingency and VAT. Our own construction rates are published in the NU Build Cost Calculator.

How NU Projects approaches it

Kitchen extensions in prime London homes are rarely simple. The recurring work is:

• Removing load-bearing walls
• Designing and installing the steel frame
• Party wall agreements
• Conservation area restrictions
• Head height and daylight, together
• Underfloor heating and controls
• Joinery and glazing at a high standard

NU Projects has delivered complex residential work across West and prime central London since 2010. That covers rear and side return extensions, wraparounds, glass box extensions, open-plan structural reconfiguration, basement and kitchen integration, and period and listed homes.

Structure early

The steel design and the construction sequence are settled early, which is what prevents the redesign that costs money later.

Planning experience

Borough planning practice and conservation policy vary, and the route is worked out for the actual property.

The extension should read as original

A good extension does not look appended. That comes from the proportions, the materials and where the roof meets the existing wall.

One team

Design, structure, glazing, services and finishes are coordinated from the outset, and the client deals with the people making the decisions.

Kitchen extensions in prime London

In Chelsea, Kensington, Fulham, Hampstead and Notting Hill, a kitchen extension often also involves basement integration, glazed roof systems, high-specification sliding doors, bespoke joinery, acoustic control and very tight site logistics.

That is where experience separates a general contractor from a specialist, and it is worth asking which of those six a firm has actually done.

Final thoughts

London has a great many kitchen extension companies, and most are good at the work they normally do. The question is which of them has built your job before.

Planning a kitchen extension in London?

If you are considering a kitchen extension and want it designed properly, structurally sound and finished to match the rest of the house, speak to us early, while the plan can still change.

Tell us about the house and we will tell you what the ground floor can take.