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
Realistic Cost Breakdown
For a typical 20m² rear extension in London:
- Structure & Build: £45,000-£60,000
- Kitchen Units & Appliances: £8,000-£25,000
- Flooring: £2,000-£4,000
- Bi-fold Doors: £3,000-£6,000
- Roof Lantern: £4,000-£7,000
- Electrics & Plumbing: £3,000-£5,000
- Decoration: £2,000-£4,000
- Total: £67,000-£111,000
Choosing Your Builder
Select a builder with proven experience in kitchen extensions. Essential checks:
- Portfolio of similar projects in London
- Structural engineer on team or partnership
- Fixed-price contracts with stage payments
- Insurance (minimum £5 million public liability)
- Recent customer testimonials and site visits
Common Pitfalls to Avoid
- Underestimating costs: Always add 15% contingency
- Ignoring Party Wall Act: Notify neighbors 2 months before
- Cheap materials: They look dated within 5 years
- Poor insulation: Meet Building Regs minimum at least
- Inadequate lighting: Plan artificial lighting early
Ready to Start Your Project?
Get a free consultation and quote for your extension or renovation project.
