Kitchen Extension Ideas for London Homes: Costs, Types and Planning

A kitchen extension is one of the most effective ways to add space, light and value to a London home — turning a cramped galley into an open room where you actually want to spend time. This guide covers the main types of extension, what they realistically cost in 2026, and the planning points worth knowing before you start.

Why extend the kitchen rather than move?

In most of London, extending is cheaper than trading up to a larger house once stamp duty, agents’ fees and moving costs are taken into account. A well-designed extension also lets you tailor the space to how your household actually lives, and a bright kitchen-diner remains one of the features buyers value most.

The main types of kitchen extension

Side return extension

The side return is the narrow strip of ground that runs alongside the back of a Victorian or Edwardian terrace. Building into it widens a previously pinched kitchen and is often the single biggest improvement you can make to a period terrace, usually within permitted development.

Rear extension

A rear extension pushes out into the garden and suits homes that need a larger footprint. Bi-fold or sliding doors and a roof light connect the room to the garden and pull daylight deep into the plan.

Wraparound extension

A wraparound combines side return and rear, giving the largest gain in floor area. It is the most involved option and more likely to need full planning permission, but it can transform the whole ground floor.

Modern kitchen extension

Design ideas that earn their keep

• Bring in daylight from two directions: roof lights over the side return plus glazing to the garden avoid the “dark middle” that spoils many extensions.

• Plan the room around how you live: zone cooking, dining and relaxing before choosing units, not the other way round.

• Choose materials you can live with: durable worktops and flooring cost more upfront but age better than the cheapest options.

• Design in storage early: full-height and under-island storage keeps an open-plan room calm and uncluttered.

Modern kitchen extension

What does a kitchen extension cost in London in 2026?

Costs vary with size, ground conditions and specification, but as a broad guide a single-storey kitchen extension in London typically starts around £75,000 and rises well beyond £120,000 for larger wraparound projects with high-end glazing and finishes. Groundworks, structural steel and drainage are the usual reasons two similar-looking projects differ in price.

For a fuller breakdown, see our guide to the cost of a house extension in London.

Planning permission and permitted development

Many side return and modest rear extensions fall under permitted development, but limits on depth, height and materials apply — and they are tighter in conservation areas or where an Article 4 direction is in force. Even when planning permission is not required, it is worth obtaining a Lawful Development Certificate so the position is documented when you come to sell. Building Regulations approval is always required.

How Studio MASS approaches kitchen extensions

We are a London-based practice and we design each extension around the specific house and how the household uses it, rather than repeating a standard template. We handle the design, the planning or lawful-development route and the technical drawings, and we can help you appoint a builder and stay involved through construction.

Ready to start?

If you are considering a kitchen extension, book a free, no-obligation consultation with Studio MASS. Email info@studio-mass.com, call 0208 638 6727, or use the Talk to Us button above.

About the author

Robert McBride BSc(Hons) MFPWS is an architectural technologist and director of Studio MASS, a London practice specialising in residential extensions, conversions and new-build homes.