Kitchen Extension Costs UK
A kitchen extension is one of the most popular home improvement projects in the UK. It combines extra living space with the heart of the home, creating open-plan kitchen-diners that suit modern family life. Here is a realistic breakdown of what you should expect to budget, what affects the price, and how to avoid common mistakes.
Typical Kitchen Extension Costs
A kitchen extension typically costs between £40,000 and £80,000 depending on size, specification and location. A standard 4m x 6m kitchen-diner extension (24 sqm) in the Midlands would typically cost £36,000-£60,000 for the building work alone, with kitchen fitting adding £8,000-£25,000+. Smaller 3m x 4m extensions can start from around £25,000 for the structure.
What Is Included in the Build Cost?
Building costs typically include foundations, walls, roof, glazing (bi-folds or sliding doors), electrics, plumbing rough-in, plastering, decoration and floor screed. The kitchen itself (units, worktops, appliances) is usually a separate budget item. Structural steelwork for removing the rear wall is also included and typically costs £2,000-£5,000 depending on span.
Kitchen Fitting Costs
The kitchen is a major cost on top of the building work. A mid-range kitchen with solid-surface worktops, soft-close units, integrated appliances and good tiling typically costs £12,000-£20,000 fully fitted. A premium kitchen with quartz or granite worktops, handleless units and high-end appliances can cost £20,000-£40,000+. Budget kitchens from £5,000-£10,000 are available but may not suit a high-quality extension.
Premium Upgrades and Their Costs
Bi-fold doors (£3,000-£6,000), roof lanterns (£2,000-£5,000), underfloor heating (£50-£80/sqm), vaulted ceilings (£2,000-£4,000 extra), and LVT or engineered oak flooring (£40-£80/sqm) all add to the specification but create a dramatically better finished space. These upgrades are where most homeowners see the biggest difference between a good extension and a great one.
What Affects Kitchen Extension Costs
The main cost drivers are size, specification level, structural complexity and ground conditions. Removing a load-bearing rear wall requires structural steelwork. Relocating drainage or soil pipes adds £1,000-£3,000. Clay soils common in Worcestershire and surrounding areas may need deeper foundations. Side-return extensions in terraced or semi-detached houses involve party wall agreements (£700-£1,500 per neighbour).
Planning Permission and Building Control
Many rear kitchen extensions fall under permitted development rights, allowing up to 3m from the rear wall (or up to 6-8m under prior approval). This avoids the cost and delay of a full planning application. All kitchen extensions require building regulations approval covering structural integrity, insulation, drainage, electrics and ventilation. Budget £400-£800 for building control fees.
Typical Timelines
A typical kitchen extension takes 10-16 weeks from groundworks to handover. The design and approval phase adds 6-12 weeks beforehand. Kitchen units typically need ordering 6-8 weeks before fitting, so early decisions on the kitchen design help avoid delays at the end of the project. Plan for 2-4 weeks without a functioning kitchen — many families use a temporary kitchen in another room.
Common Mistakes to Avoid
The biggest mistake is underbudgeting the kitchen itself — many homeowners spend heavily on the building work but leave too little for the kitchen that goes inside it. Other common errors include not ordering the kitchen early enough (causing delays), forgetting to budget for landscaping and making good outside, not allowing a 10-15% contingency, and choosing a builder based purely on price without checking quality and references.
When to Get a Professional Estimate
Once you know roughly what you want — the size, layout and specification level — the next step is getting a detailed estimate. Use our AI estimate generator for a quick ballpark figure, then book a consultation to discuss your specific project. A site visit lets us assess access, drainage, structural requirements and any other factors that affect the price.
Frequently Asked Questions
How much does a kitchen extension cost?
A kitchen extension typically costs between £40,000 and £80,000 for building work plus kitchen fitting, depending on size and specification.
How long does a kitchen extension take to build?
A typical kitchen extension takes 10-16 weeks from groundworks to handover. Add 6-12 weeks for design and approvals.
Can I extend my kitchen without planning permission?
Many rear kitchen extensions fall under permitted development rights, allowing up to 3m from the rear wall or up to 6-8m under prior approval.
How much does a kitchen cost to fit inside an extension?
A mid-range kitchen typically costs £12,000-£20,000 fully fitted including units, worktops, appliances and tiling. Premium kitchens can cost £20,000-£40,000+.
Can I live at home during a kitchen extension?
Yes, most families stay in the home. Plan for 2-4 weeks without a functioning kitchen — set up a temporary kitchen in another room with a microwave, kettle and portable hob.
What adds the most value in a kitchen extension?
Bi-fold or sliding doors opening onto the garden, a roof lantern for natural light, underfloor heating and a high-quality kitchen all add significant value and saleability to the finished space.