Contents
- 1. Kitchen Extension Costs in London: A Complete Budget Guide for 2025
- 2. What a Kitchen Extension Project Involves
- 3. The Extension Structure: Build Cost Only
- 4. The Kitchen Fit-Out: What Does the Kitchen Actually Cost?
- 5. Associated Internal Works
- 6. Underfloor Heating in a Kitchen Extension
- 7. Professional Fees for a Kitchen Extension in London
- 8. A Realistic Total Budget for a London Kitchen Extension
- 9. rcbGroup and Kitchen Extensions
Kitchen Extension Costs in London: A Complete Budget Guide for 2025
The kitchen extension is the most common single project undertaken by London homeowners -- and the one where budget surprises are most frequent. This guide breaks down the full cost of a kitchen extension project into its main components and provides realistic 2025 ranges based on London construction costs.
What a Kitchen Extension Project Involves
A typical London kitchen extension project involves:
- The extension structure: the new building that extends the ground floor footprint
- The kitchen itself: units, worktops, appliances, and installation
- Associated internal works: opening up the rear wall of the original house, reconfiguring the ground floor, flooring, lighting, decoration
- Professional fees: architect, structural engineer, party wall surveyor where applicable
The Extension Structure: Build Cost Only
For a standard London single-storey rear extension of 15--25 m2 (a typical kitchen extension footprint):
Standard specification (flat roof, aluminium bi-fold or sliding doors, basic finishes):
- Extension structure to shell: £45,000--£75,000 (approximately £2,800--£3,500 per m2)
Mid-range specification (larger glazed openings, better quality bi-folds, underfloor heating prep):
- £65,000--£100,000
High specification (slim aluminium frameless glass, large lantern rooflight, underfloor heating, premium finishes):
- £90,000--£150,000+
These build costs cover the extension structure only, not the kitchen fit-out.
The Kitchen Fit-Out: What Does the Kitchen Actually Cost?
The kitchen units, appliances, worktop, and installation are a separate major cost item. London homeowners frequently underestimate this element. Realistic ranges:
Budget kitchen (flatpack or entry-range units from IKEA, Howdens, or Wren; laminate worktop; basic appliances):
- Units, worktop, appliances, and sink: £8,000--£15,000 supplied
- Installation (by contractor): included in build programme or £3,000--£6,000
Mid-range kitchen (rigid construction trade units such as Magnet or Symphony mid-range; stone or quartz worktop; standard appliances):
- Units, worktop, appliances, and sink: £15,000--£30,000 supplied
- Installation: £4,000--£8,000
Premium kitchen (bespoke or semi-bespoke units such as Neptune, deVOL, Tom Howley, or Martin Moore; premium stone worktop; integrated high-end appliances):
- Units, worktop, appliances, and sink: £30,000--£80,000+ supplied
- Installation: £6,000--£15,000
Bespoke luxury kitchen:
- £80,000--£200,000+ (true bespoke joinery, Gaggenau or Miele appliances throughout, book-matched stone)
Associated Internal Works
The internal works to open up and reconfigure the ground floor are a significant additional cost:
- Structural opening in rear wall (single steel beam + making good): £5,000--£12,000
- Reconfiguration of ground floor layout (additional partitions, relocated staircase -- if applicable): £8,000--£25,000+
- New flooring throughout ground floor (engineered oak, tiles, or similar): £4,000--£12,000 depending on area and specification
- New lighting design and installation throughout ground floor: £3,000--£8,000
- Decoration and finishes throughout ground floor: £4,000--£10,000
Underfloor Heating in a Kitchen Extension
Underfloor heating (UFH) in the extension slab is highly desirable for kitchen extensions but adds cost:
- Wet UFH (hot water through pipes): £2,500--£6,000 for a 15--25 m2 extension (materials and installation in the slab, including manifold, not including boiler upgrade if needed)
- Electric UFH: £1,500--£3,500 for a 15--25 m2 extension (higher running cost than wet system)
Professional Fees for a Kitchen Extension in London
- Architect (planning and technical drawings): £4,000--£10,000 depending on complexity and conservation area
- Structural engineer: £1,200--£3,000
- Party wall surveyor: £1,500--£5,000 (where party wall act is triggered)
- Planning application fee: £258
- Building Control: £800--£2,500
Total professional fees: £7,000--£20,000 for a typical London kitchen extension project.
A Realistic Total Budget for a London Kitchen Extension
Pulling the components together, a realistic total budget range for a 20 m2 London kitchen extension with a mid-range kitchen and mid-range specification:
| Element | Cost range |
|---|---|
| Extension structure (20m2, mid-range) | £60,000--£90,000 |
| Kitchen fit-out (mid-range) | £18,000--£35,000 |
| Internal reconfiguration | £10,000--£20,000 |
| Flooring and decoration | £6,000--£15,000 |
| Professional fees | £8,000--£18,000 |
| Total | £102,000--£178,000 |
For a high-specification project with a premium kitchen, the total budget can easily reach £200,000--£350,000+.
rcbGroup and Kitchen Extensions
rcbGroup delivers kitchen extensions across London, from design through to handover. We provide detailed estimates based on proper drawings and a structured scope so that our clients know what they are buying before they commit.
Contact our team to discuss your London kitchen extension project.
Want advice on your own project?
Pick whatever suits you. We'll look at what you have (drawings, photos or quotes) and tell you honestly what the next step should be.
Prefer to phone? Call +44 7359 872594.
Important Note
This guide is for general information only. Building regulations, planning rules, and legal requirements change regularly and vary by local authority. Always seek professional advice specific to your project and location. To talk through your own project, book a project review.
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