Kitchen Extension London 2025: Complete Guide
Transform your home with a kitchen extension. Everything you need to know about design, costs, layouts, and planning for London properties.
Key Takeaways
- Kitchen extensions are the most popular extension type in London
- Expect £75,000-120,000 total (structure + kitchen fit-out)
- Bi-fold or sliding doors maximize light and garden connection
- Get accurate cost estimate for your kitchen extension (Free)
Why Extend for a Kitchen?
Kitchen extensions are the most popular home improvement in London. They solve the classic problem of Victorian and Edwardian homes: small, dark kitchens separated from living spaces.
A well-designed kitchen extension creates an open-plan living space that becomes the heart of your home. It adds significant value, improves daily living, and connects your home to the garden.
Property value impact: Kitchen extensions typically return 75-100% of their cost in added property value, and often more in family homes where open-plan living is highly desired.
Extension Types: Rear, Side Return, or Wrap-Around
Rear Extension
The most straightforward option. Extends straight back from your existing kitchen into the garden.
- Best for: Detached and semi-detached houses with wide rear facades
- Typical depth: 3-6m (depending on permitted development rights)
- Cost range: £45,000-70,000 (structure only)
Side Return Extension
Fills in the narrow side passage (alley) typical of Victorian terraced houses. Instantly transforms a galley kitchen into a generous open space.
- Best for: Victorian terraced houses with side passages
- Typical width: 1.5-2.5m additional width
- Cost range: £35,000-55,000 (structure only)
Planning note: Side return extensions often require planning permission in London, especially in conservation areas or where Article 4 directions apply.
Wrap-Around Extension
Combines rear and side return extensions in an L-shape. The ultimate kitchen extension for maximum space and light.
- Best for: Victorian terraced houses wanting maximum space
- Creates 25-40m² of new space
- Cost range: £60,000-95,000 (structure only)
Open-Plan Kitchen-Diner Layouts
The key benefit of a kitchen extension is open-plan living. Removing walls between kitchen, dining, and living creates a flexible family space with sight lines throughout.
Typical Zones
Cooking Zone
Hob, oven, extraction. Usually along one wall or in an island configuration.
Preparation Zone
Sink, counters, storage. Ideally with natural light from side or rear glazing.
Dining Zone
Table and chairs, often positioned near bi-fold doors for garden access.
Living Zone
Sofas, comfortable seating. Sometimes included in larger extensions (40m²+).
Structural consideration: Open-plan designs require steel beams to span the width of the space. Your structural engineer will calculate beam sizes based on floor loads above.
Kitchen Layout Options
Island Layout
The most popular choice for kitchen extensions. A central island provides:
- Extra prep space and storage
- Casual seating (breakfast bar)
- Social cooking (facing into the room)
- Minimum space needed: 4m x 4m kitchen area
Galley Layout
Two parallel runs of cabinets. Efficient for smaller extensions where an island wouldn't fit.
- Best for: Narrow extensions or side returns
- Excellent work triangle efficiency
- Minimum corridor width: 1.2m between units
L-Shaped Layout
Kitchen along two adjacent walls, leaving the rest open for dining. Works well in corner extensions or wrap-around layouts.
- Best for: Medium-sized extensions with side and rear glazing
- Maximizes dining space
- Good work triangle without through-traffic
Bi-Fold Doors and Glazing
Large glazed openings are essential to kitchen extensions. They provide:
- Natural light (crucial in extensions that project away from house windows)
- Visual connection to garden
- Indoor-outdoor living in summer
Door Options
Bi-Fold Doors
- Fold back completely for full opening
- Most popular choice for extensions
- Cost: £2,000-4,000+ (3-4m span)
Sliding Doors
- Slimmer sightlines, more glass
- Less stack-back space needed
- Cost: £3,000-6,000+ (3-4m span)
Glazing tip: Aluminum frames are standard for extensions. Powder-coated finishes (anthracite grey, black) are most popular in London.
Roof Glazing
Flat roof extensions can incorporate roof lights (skylights) or structural glazing for additional light. Essential for deep extensions or side returns where rear glazing alone isn't enough.
- Standard roof lights: £800-1,500 each
- Structural glass roofs: £5,000-15,000+
- Building regs require solar control glazing to prevent overheating
Kitchen Extension Costs London 2025
Budget £75,000-120,000 total for a typical London kitchen extension including kitchen fit-out. This breaks down as:
Cost Breakdown
Foundations, walls, roof, glazed doors, flooring, plastering, electrics, heating
Cabinets, worktops, appliances, sink, tap, tiling
Architect, structural engineer, party wall surveyor, building control
Planning drawings, application fee, consultants
Price per Square Meter
London kitchen extensions typically cost £2,500-3,500/m² for the structure (before kitchen fit-out). This is higher than basic extensions because of:
- Large spans of expensive bi-fold or sliding doors
- High-spec finishes (underfloor heating, quality flooring)
- Steelwork for open-plan spans
- Integration with existing house (removing walls, leveling floors)
Budget tip: Get your cost estimate before detailed design. Kitchen extensions vary significantly in price depending on size, glazing spec, and finish level.
Design Considerations
The Work Triangle
Classic kitchen design principle: the sum of distances between sink, hob, and fridge should be 4-8m for efficiency. In open-plan extensions, this still applies but is less rigid.
Storage
Plan for generous storage. A family kitchen needs:
- Base units along at least 4m of wall (ideally 5-6m)
- Tall units or pantry for bulk storage
- Island storage if applicable
Flow and Circulation
Consider how people move through the space:
- Avoid through-routes that cross the work triangle
- Minimum 1.2m circulation space around islands
- Clear sight lines from kitchen to dining/living areas
- Direct access route to garden without crossing cooking zone
Lighting Strategy
Natural Light
Maximizing daylight is crucial. Use:
- Full-width bi-fold or sliding doors on rear elevation
- Roof lights or structural glazing, especially for side returns
- High-level windows on side returns (if boundary allows)
- Light-colored finishes to bounce light deeper into space
Task Lighting
Focused lighting for cooking and prep:
- Under-cabinet LED strips for counter lighting
- Pendant lights over island (if applicable)
- Downlights positioned above hob and sink
Ambient Lighting
General lighting for the whole space:
- Recessed downlights (LED) on dimmers throughout
- Feature pendants over dining table
- Separate circuits for different zones (kitchen/dining/living)
Flooring and Heating
Flooring Options
Large Format Tiles
Most popular choice. Durable, water-resistant, works well with underfloor heating.
Cost: £60-120/m² supplied and fitted
Engineered Wood
Warmer aesthetic, good for kitchen-living spaces. Must be compatible with UFH.
Cost: £70-150/m² supplied and fitted
Polished Concrete
Contemporary look, excellent thermal mass. Requires specialist installer.
Cost: £100-180/m² supplied and fitted
Underfloor Heating
Highly recommended for kitchen extensions. Benefits include:
- Even heat distribution (no cold spots near glazing)
- No radiators taking up wall space
- Pairs well with heat pumps (low temperature heating)
- Warm floor feel (especially nice on tiles)
Cost: £60-90/m² including screed, pipework, manifold, controls.
Planning and Permitted Development
When You Need Planning Permission
Kitchen extensions often require planning permission in London because:
- Side return extensions rarely qualify for PD (7m boundary rule)
- Many boroughs have Article 4 directions removing PD rights
- Conservation areas have restricted PD rights
- Extensions deeper than 3m (terraced) or 4m (detached) need Prior Approval minimum
Planning Timeline and Cost
| Stage | Timeline | Cost |
|---|---|---|
| Prior Approval | 6 weeks | £96 application |
| Householder Planning | 8-12 weeks | £258 application |
| Design drawings | 4-8 weeks | £2,500-5,000 |
| Building Regulations | Parallel with planning | £1,500-3,000 |
Pro tip: Check your permitted development rights before investing in architect fees. Our free PD checker gives instant results.
Get Your Kitchen Extension Estimate
Free instant estimate for your kitchen extension project including:
- Structure cost breakdown
- Kitchen fit-out allowance
- Professional fees estimate
- Planning requirements check
Frequently Asked Questions
How long does a kitchen extension take to build?
Typical timeline is 3-4 months for construction after planning approval. This includes foundations, structure, roof, glazing, and first fix. Add 2-3 weeks for kitchen installation and finishing.
Can I live in the house during construction?
Yes, usually. The most disruptive phase is when the existing rear wall is removed (typically 1-2 weeks). Many families stay during construction and use temporary kitchen setup in another room. Alternatively, plan a holiday during the wall removal phase.
Do I need party wall agreements for a kitchen extension?
Usually yes in terraced and semi-detached houses. You need party wall agreements if: (1) building on or near the boundary with neighbors, (2) excavating foundations within 3m of neighbor's structure, or (3) working on a shared wall. Budget £1,000-2,500 for party wall surveyor fees.
Should I design the kitchen before or after planning approval?
Concept first, detailed design after. Know your desired layout type (island, galley, L-shape) and approximate kitchen zone size for the planning drawings. Detailed kitchen design, exact unit sizes, and appliance selection can wait until after planning approval to avoid wasted design fees.
What's the best way to connect old and new spaces?
Fully opening up with a steel beam creates the most successful spaces. Half-walls or partial openings feel compromised. Budget for full-width openings and large steel beams. Floor levels should match—step-downs feel clunky and aren't family-friendly. Budget for floor buildup if needed.
How much value does a kitchen extension add?
Well-executed kitchen extensions typically return 75-100% of cost in added value. In family homes where open-plan living is highly desired, returns can exceed 100%. However, value also comes from improved quality of life and daily living experience, not just resale value.
Summary
Kitchen extensions are the most transformative home improvement you can make. They solve the problems of small, dark kitchens while creating valuable open-plan living space that connects to your garden.
Budget £75,000-120,000 total for structure and kitchen fit-out in London. Prioritize good design, generous glazing, and quality construction over luxury kitchen finishes. The structure lasts 100 years; kitchens can be updated in 15.
Start with feasibility: Get your cost estimate and check planning requirements before investing in detailed design. This ensures your budget aligns with your ambitions.