If you love your home but your kitchen feels cramped, a kitchen extension might be the perfect upgrade. Before you make any decisions, though, it’s essential to ask: how much does a kitchen extension cost?
In 2025, UK kitchen extension prices vary greatly depending on size, location, and finish level. This guide breaks down all the key costs, hidden expenses, and tips to keep your budget on track.
Why Extend Your Kitchen?
Kitchens are often the heart of a home. Whether you need more space for cooking, want an open-plan layout, or simply crave better natural light, extending your kitchen is a smart investment.
Not only can it improve daily living, but a well-designed kitchen extension can also boost your property’s value. In some areas, you may see an increase of 10 to 20 percent in resale value after a kitchen extension is completed.
Average Kitchen Extension Cost in 2025
Here is a general breakdown of kitchen extension costs across the UK:
| Size & Finish Level | Estimated Cost Range |
| Small basic (3x3m) | £12,000 to £16,000 |
| Medium average (4x4m) | £26,000 to £34,000 |
| Large deluxe (5x6m) | £67,000 to £100,000 |
These figures include construction, fittings, and kitchen installation. Costs can rise quickly if you choose luxury finishes, bespoke designs, or have structural challenges.
Kitchen Extension Cost Per Square Metre
- Basic build: £1,750 per m²
- Mid-range: £2,100 per m²
- High-end: £2,350 per m² and above
These rates include structural work, but not necessarily fittings or finishes. Kitchens typically cost more than other room extensions because they involve plumbing, electrics, ventilation, and appliances.
Realistic Example: 5×3 Metre Extension (15m²)
Let’s look at a mid-range kitchen extension project and how the budget might break down:
| Task or Item | Estimated Cost |
| Architectural drawings | £800 |
| Planning approval | £250 |
| Foundation and structure | £16,000 |
| Roofing and insulation | £3,500 |
| Bi-fold doors | £2,000 |
| Kitchen units and appliances | £12,000 |
| Electrics and plumbing | £4,000 |
| Flooring and tiling | £2,500 |
| Painting and finishing | £1,200 |
| Waste clearance | £700 |
| Estimated Total | £42,950 |
Always add a 10 to 15% contingency for changes or delays.
What Affects the Cost?
Several things can increase or decrease the final cost of your kitchen extension:
- Location: London and the South East often have higher labour and material costs.
- Access: Narrow driveways or awkward garden layouts can slow progress.
- Design: A simple box shape with a flat roof is cheaper than a wraparound with pitched roofing.
Utilities: Moving gas lines or water pipes adds extra work. - Finishes: Granite countertops and custom cabinets cost much more than standard units.
Planning Permission and Building Regulations
You might not need full planning permission. Many kitchen extensions fall under permitted development, especially single-storey rear extensions up to 3 metres on a semi-detached or 4 metres on a detached house.
However, you will still need:
- Building regulations approval
- Structural drawings
- Inspection sign-offs at key stages
Planning approval typically takes 6 to 8 weeks. Budget £300 to £600 for drawings and submission fees.
Standard Extra Features and Their Cost
Enhancing your kitchen can improve both style and usability, but these extras come at a price:
| Feature | Cost Estimate |
| Underfloor heating | £1,000 to £2,000 |
| Roof lantern or skylight | £800 to £1,500 |
| Smart lighting | £500 to £1,000 |
| Custom kitchen units | £4,000 to £8,000 |
Choose upgrades that add value without exceeding your budget.
How to Save Money on Your Kitchen Extension
- Stick to a simple shape
Square or rectangular layouts cost less to build. - Choose standard finishes
Pre-fabricated units and laminate flooring offer good quality at lower prices. - Project manage yourself
Doing the coordination can save 10 to 15%, but it requires time and effort. - Buy during sales
Appliances, tiles, and fittings often go on sale around the end of the year or during spring promotions. - Phase your work
Complete the structure first, then finish interiors as budget allows
Hidden Costs to Watch For
Many homeowners overlook these expenses:
- Structural surprises (weak foundations or damp): £2,000 to £5,000
- Delays due to weather or materials: Adds 10 to 15%
- Planning appeal fees if rejected: £200 to £500
- Insurance upgrades during works: £100 to £400
Always include a buffer of at least 10% for surprises.
Is It Worth It?
Yes, in most cases. A well-built kitchen extension improves functionality, increases light, and boosts property value. It can make your home more appealing to future buyers and more comfortable for daily living.
Some real estate agents estimate kitchen extensions add 10 to 15% to the resale value of homes in desirable locations.
Final Thoughts
So, how much does a kitchen extension cost in the UK? The short answer is: it depends. On average, you can expect to spend between £30,000 and £50,000, but high-end builds can cost upwards of £100,000.
With careful planning, wise design choices, and the right builder, you can extend your kitchen without blowing your budget. Take your time to gather quotes, research local rules, and consider both must-haves and nice-to-haves.
FAQs:
1- How much does a kitchen extension cost?
In 2025, the average kitchen extension in the UK costs between £30,000 and £50,000. Prices depend on various factors like extension size, level of finish, choice of materials, and your location. Smaller extensions with standard fittings may cost less, while large or high-end builds can easily exceed £70,000 to £100,000.
2- How much does a small kitchen extension cost?
A small kitchen extension, such as a 3m x 3m space, can cost anywhere from £12,000 to £26,000, depending on the complexity of the build and the finishes used. This size is ideal for adding extra cooking space or opening up a cramped layout. Keeping the design straightforward helps keep costs down.
3- How much is a kitchen extension with bi-fold doors?
If you’re planning to add bi-fold doors to your kitchen extension, expect to pay an additional £1,500 to £3,000 on top of your base build cost. These doors offer a stylish way to connect indoor and outdoor spaces and bring in natural light. A mid-sized kitchen extension with bi-fold doors may cost around £35,000 to £55,000 in total.
4- How much value does a kitchen extension add?
A kitchen extension can add 10 to 20% to the value of your home, depending on the quality and location. Homes in high-demand areas often benefit more. The extension’s impact is greatest when it improves the flow of the ground floor, enhances natural light, or adds functional dining or living space.
5- Do you need planning permission for a kitchen extension?
Not always. Many kitchen extensions fall under permitted development rights, which means you may not need planning permission if the build meets specific criteria. However, if you’re extending beyond certain limits, working near boundaries, or altering the front of the house, you will likely need formal permission. It’s best to check with your local planning office before starting.
6- How long does a kitchen extension take?
The average kitchen extension takes 12 to 16 weeks to complete once construction begins. Smaller or simpler projects may take less time, while larger or more complex builds can take longer. You should also account for planning, design, and approval stages, which can add another 6 to 8 weeks before work begins.
7- How much does a side return kitchen extension cost?
A side return kitchen extension typically costs between £30,000 and £60,000, depending on size, materials, and finish. This type of extension is popular for Victorian or Edwardian terraced houses with unused space along the side. It’s a great way to expand your kitchen without sacrificing much garden space.
