The Complete Guide to Kitchen Extensions in London [2026]

Kitchen extensions have become the gold standard for adding value and living space to London homes. This comprehensive guide covers everything from initial planning through to completion, with real costs, design ideas, and expert insights.

Why Kitchen Extensions Are Popular in London

In a city where property prices per square foot are among the highest in the world, extending rather than moving has become the preferred option for growing families. Kitchen extensions offer the perfect solution, combining additional space with improved functionality and significant property value increases.

The Financial Case

A well-executed kitchen extension typically adds 10-15% to your property value while costing significantly less than the equity gain. For a £600,000 property in London, a £70,000 extension could add £90,000 in value—a £20,000 profit before you even consider the lifestyle benefits.

Types of Kitchen Extensions

1. Rear Extension

The most common type in London, rear extensions extend the back of your property into the garden. Victorian and Edwardian terraced houses are ideal candidates, typically gaining 15-25 square metres of additional space.

Best for: Creating an open-plan kitchen-dining area

Typical cost: £2,000-£3,000 per m²

Timeline: 8-12 weeks

2. Side Return Extension

Perfect for Victorian/Edwardian properties with a narrow side passage (side return). This “dead space” can be reclaimed to create a full-width kitchen.

Best for: Maximizing width and creating a sociable kitchen space

Typical cost: £1,800-£2,500 per m²

Timeline: 6-10 weeks

3. Wraparound Extension

Combining both rear and side return extensions, this option maximizes ground floor space, often doubling the size of your kitchen/dining area.

Best for: Creating a spectacular open-plan family hub

Typical cost: £2,200-£3,500 per m²

Timeline: 12-16 weeks

Planning Permission & Building Regulations

Permitted Development Rights

Many single-storey rear extensions fall under Permitted Development, meaning you dont need full planning permission. The rules allow:

Up to 3 metres extension for attached houses
Up to 4 metres for detached houses
Maximum height of 4 metres
No extension beyond the side elevation facing a highway

When You Need Planning Permission

You will need planning if your extension:

Exceeds Permitted Development limits
Is in a conservation area or listed building
Has already used Permitted Development rights
Covers more than 50% of the garden

Design Considerations

Maximizing Natural Light

The key to a successful kitchen extension is flooding it with natural light. Popular solutions include:

Roof Lanterns: Glass roof structures (£3,000-£8,000)
Skylights: Velux or similar (£800-£1,500 each)
Bi-fold Doors: 3-4 panel sets (£2,500-£6,000)
Crittal-style Windows: Industrial aesthetic (£4,000-£10,000)

Internal Layout Options

Your extension layout should reflect how you live. Common configurations:

Galley Kitchen + Dining: Kitchen along one wall, dining table in the extension
Island Kitchen: Central island with seating, dining area beyond
L-Shaped Kitchen: Kitchen wraps around two walls, maximizing prep space