Kitchen Extension Cost Guide for UK Homes

A kitchen extension can look deceptively simple on a floor plan. In practice, the budget covers much more than walls and kitchen units: foundations, structural openings, drainage, insulation, roofing, glazing, electrics and plumbing all need to work together. The Federation of Master Builders currently puts the average UK single-storey extension at around £1,800 to £3,000 per m², providing a useful starting benchmark. For tailored advice, explore Prime Construction’s extension services or contact the team on 01795 431378.

How much does a kitchen extension cost in the UK?

As a starting point, a single-storey kitchen extension in the UK may cost around £1,800–£3,000 per m² for construction work, with the final kitchen extension cost depending on size, specification, location and what is included in the quotation.

For example, a 20m² extension would give a rough construction range of £36,000 to £60,000 as a broad benchmark, before the cost of the kitchen and any project-specific items not included in the benchmark. This is an example rather than a recommended or typical kitchen-extension size.

A rear kitchen extension is often the simplest way to add floor space. Side-return and wraparound extensions can involve more complicated structural work, drainage and access. In Kent and the wider South East, local labour rates and site conditions can also affect the final quotation.

What is included in a kitchen extension cost breakdown?

A realistic budget combines several stages, and your quotation should state what is included and excluded. Separate construction costs from professional fees, planning, kitchen supply and installation, finishes and contingency.

Professional fees may cover drawings, structural calculations and specialist input. In England, a standard householder planning application currently costs £548. Some larger single-storey rear extensions under permitted development are subject to a prior approval process.

Construction normally covers foundations, walls, structural steel, roofing, insulation, windows and doors. Ground conditions, trees and drains can make foundations more complex.

Separate the extension build from the kitchen fit-out. A construction quote may exclude units, worktops, appliances and some finishes, so check exactly what is included. Prime Construction’s kitchen services can be considered alongside the extension itself.

What factors can increase the cost of a kitchen extension?

Size matters, but it is not the only variable. Smaller extensions can still have substantial fixed costs because foundations, structural work and site setup are relatively fixed costs.

The existing house is equally important. Removing a load-bearing wall may require structural steel and temporary support. Drainage and restricted access can also add cost.

Glazing and roof design also influence the budget. Bifold doors, roof lanterns and large glazed openings can create a bright kitchen, but may require additional structural design and higher-specification products.

Planning and Building Regulations should be considered at design stage. In England, permitted development rights have specific limits and conditions, and they do not remove Building Regulations requirements.

How can you keep a kitchen extension within budget?

Set the layout and specification before construction begins. Moving a doorway, sink, drainage run or appliance position after work starts can be more expensive than resolving it during design.

If budget is a priority, keep the structural form relatively simple. A straightforward rear extension will often be simpler to price than a wraparound design with several roof junctions and extensive glazing.

Separate essentials from upgrades. Good insulation, ventilation and compliant electrical and plumbing work are not sensible areas to cut. Premium appliances and bespoke cabinetry offer more flexibility if the budget needs reducing.

Allow a contingency for genuine unknowns, particularly with older properties. Existing foundations, hidden services and drainage may not be fully visible before opening up the building, so ask how unforeseen work will be priced.

What should you check before choosing a builder?

Do not compare quotations on the headline figure alone. Check the specification, provisional sums, exclusions, payment stages and programme.

Looking at a builder’s past projects can help you judge the quality of extensions they have delivered and whether their finished work matches the standard you want. A clear scope helps coordinate structural, plumbing, electrical and kitchen installation work.

A kitchen extension budget starts with the right scope

The most reliable kitchen extension cost is based on your actual property, layout and specification. Per-square-metre figures are useful for an initial sense check, but foundations, structural alterations, glazing, services and kitchen finishes can move the final price.

Plan the design before construction, make the quotation transparent and allow for unknowns. If you are considering an extension in Sittingbourne, Kent or the surrounding areas, contact Prime Construction to discuss your project.

Frequently Asked Questions

Is a kitchen extension cheaper than moving house?

It depends on the property, specification and local market. Extending can be practical if your location works for you, but compare the full cost of the extension, including professional fees, construction, kitchen and contingency, with selling, buying and moving.

Does a rear kitchen extension need planning permission?

Not always. Some single-storey rear extensions may fall within permitted development rights if they meet all relevant limits and conditions. Larger single-storey rear extensions can be subject to a prior approval process.

What is the biggest cost in a kitchen extension?

Building work is often the largest part of the budget, but there is no universal answer. Foundations, structural steel, glazing and kitchen specification can each have a substantial effect. A detailed quotation should show where the main allowances sit.