How Much Does a Kitchen Extension Cost in the UK?

A kitchen extension — the most popular home improvement in the UK — typically costs between £40,000 and £120,000 all-in (extension build plus new kitchen). The wide range reflects significant variation in extension size, specification, and the kitchen itself.

Budget Level	Extension Build	Kitchen Fit-Out	Total (exc. VAT)
Budget	£25,000 – £40,000	£5,000 – £12,000	£30,000 – £52,000
Mid-range	£40,000 – £65,000	£12,000 – £25,000	£52,000 – £90,000
Premium	£65,000 – £100,000	£25,000 – £60,000+	£90,000 – £160,000+

The extension build and the kitchen fit-out are usually separate contracts. Most contractors price the build; a kitchen supplier or specialist fits the kitchen.

Extension Build Costs

A kitchen extension is typically a single-storey rear extension. Build costs follow general extension pricing:

Floor Area	Cost Per m² (mid-spec)	Total Build Cost
15m²	£2,000 – £2,800	£30,000 – £42,000
20m²	£1,900 – £2,600	£38,000 – £52,000
25m²	£1,800 – £2,500	£45,000 – £62,500
30m²	£1,700 – £2,400	£51,000 – £72,000

Cost per m² reduces slightly as the extension gets bigger — fixed costs like scaffold, foundations, and structural steelwork are spread over more floor area.

The cost of bifold and sliding doors

Bifold and sliding glazed doors are popular on kitchen extensions but add significantly to cost:

Door Type	Typical Supply and Fit Cost
UPVC bifolds (3–4 panel)	£2,500 – £4,500
Aluminium bifolds (3–4 panel)	£4,000 – £7,500
Aluminium sliding doors	£3,500 – £7,000
Roof lantern (1.5m × 2m)	£2,500 – £5,000

Structural opening costs

Opening up the original kitchen wall to connect to the extension requires steelwork. A single beam spanning up to 4m costs £2,000–£4,500 including beam, padstones, decorating, and making good.

Kitchen Fit-Out Costs

Kitchen costs vary enormously by specification:

Specification	Typical Kitchen Cost
Budget (flatpack, own supply)	£3,000 – £8,000
Mid-range (rigid, integrated appliances)	£10,000 – £20,000
High-end (bespoke, quartz worktops)	£20,000 – £45,000
Designer / luxury	£45,000 – £100,000+

Kitchen fit-out costs include units, worktops, integrated appliances, and installation. They exclude building works (electrics, plumbing, flooring) which are usually handled by the main contractor.

What’s Typically Included in a Kitchen Extension Quote?

When getting quotes from builders, always clarify what is and isn’t included:

Usually included:

Groundworks and foundations
External walls and roof
External doors/windows (standard UPVC)
Structural steelwork (one standard opening)
Insulation to Building Regs standard
Internal plasterboard and skim
Electrical first fix (circuits to kitchen — no sockets fitted)
Plumbing first fix (hot/cold to kitchen position)
Underfloor heating rough-in (if specified)

Usually excluded — clarify these:

Kitchen units, worktops, and appliances
Premium bifold/sliding doors (often priced separately)
Roof lantern
Floor finishes (tile, wood, vinyl)
Electrical second fix (sockets, switches)
Plumbing second fix (boiler works, undersink connection)
Landscaping and making good the garden
VAT (20%)

Regional Cost Variation

Region	Build Cost Premium vs National Average
Inner London	+30–40%
Outer London	+15–25%
South East	+10–15%
South West / East	+5–10%
Midlands	±0%
North West / Yorkshire	−5–10%
North East	−10–15%

How to Price a Kitchen Extension Accurately

Kitchen extensions involve multiple trades — groundworkers, bricklayers, carpenters, roofers, electricians, plumbers, plasterers, and tilers — each with their own materials. Pricing manually means contacting multiple suppliers and building up each trade separately.

PricingPro generates fully itemised kitchen extension estimates in minutes. Describe the job (“25m² single-storey rear extension with bifolds, mid-spec, Birmingham”) or upload your drawings, and the AI pulls live prices across all trades and suppliers simultaneously.

Price a kitchen extension now →

FAQs

Do I need planning permission for a kitchen extension? Most single-storey rear extensions up to 3m deep (semi/terrace) or 4m deep (detached) qualify as permitted development and don’t need planning permission. Larger extensions or side extensions typically require an application. Check with your local planning authority before starting.

How long does a kitchen extension take to build? From groundworks start to final handover, most kitchen extensions take 14–20 weeks. Add the kitchen installation time (typically 2–5 days) after the main works complete. Planning permission (if required) typically adds 8–10 weeks before work starts.

Should I get a separate quote for the kitchen? Yes — kitchen supply and fit is almost always separate from the building works. Get your kitchen specification confirmed early so the builder can price for the correct electrical and plumbing first fix positions.

What ROI does a kitchen extension add? A kitchen extension is consistently one of the highest-return home improvements. In most parts of the UK, a well-executed kitchen extension adds 5–15% to a property’s value — and often significantly improves its saleability.

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