Ideas and inspiration for rear extensions
Rear extensions are a versatile way to expand your square footage and connect with your garden. Take a look at some inspiring designs to spark ideas for your own project.
Kingsbridge Road, Merton
Ground floor extension
Benhurst Gardens, Croydon
Ground floor extension
Kellerton Road, Lewisham
Ground floor extension
Beverley Close, Epsom and Ewell
Ground floor extension
Grampian Gardens, Barnet
Ground floor extension
Badgers, Epping Forest
Ground floor extension
Upminster Road, Havering
Ground floor extension
Lamberhurst Road, Lambeth
Ground floor extension
Pontes Avenue, Hounslow
Ground floor extension
Coteford Street, Wandsworth
Ground floor extension
Herbert Gardens, Brent
Loft and ground floor extensions
Cambridge Gardens, Kensington and Chelsea
Ground floor extensionWhat is a rear extension?
What is a rear extension?
A rear extension involves expanding your home out into the garden to create more room. It’s a flexible way to add anything from a heart-of-the-home kitchen, to a bright family living area or an extra bedroom upstairs, and it can completely transform how you use your house. Because rear extensions sit at the back of your property, they often allow for more natural light and an easy connection to the outdoors, making them one of the most popular and versatile types of home extension. And, as a bonus, they’ll almost certainly add value to your property.
What are the different types of rear extensions?
Rear extensions usually come in two main forms, depending on how much space you want to add and how your home is designed:
Single storey rear extension
Extending at ground level into your garden can create spacious kitchens, dining rooms, or bright open-plan living areas, with bifold doors a popular addition.
Double storey rear extension
If your layout allows, a double storey rear extension is built over two floors at the back of your home. The end result is a larger living space downstairs, plus extra bedrooms or bathrooms upstairs.
Example extensions with build costs
How much does a rear extension cost in 2025?
Because rear extensions can look so different, in size, complexity, location and more, it’s never easy to pin down an exact cost. Resi does have some data on ground floor rear extensions, though, taken from all our recent projects. In 2025, you can assume it will cost somewhere between £50,000 and £90,000 for a basic single-story rear extension around 3m x 4m in size. For something larger (4m x 6m) and with bifold doors, the cost would go up to £80,000 to £140,000. And for a high-spec extension with premium finishes, the cost will be between £100,000 - £180,000. If you’re building a double storey rear extension, it would be more like £140,000 - £180,000 for standard spec, and a much higher figure for a more luxury finish. That’s just construction costs, so any decoration, fixtures and fittings and landscaping will need to be factored in on top. And if you’re based in London or the surrounding areas, you should assume your quote will be at the upper end of that range.
Do you need planning permission for a rear extension?
Do you need planning permission for a rear extension?
Planning a rear extension? Good news: you may not need planning permission if you stay within permitted development limits. These can be complicated, though, so it’s worth getting some expert advice to make sure you understand them properly. Permitted development rules include limits on height, materials you use, and size of the extension. For example, you can typically extend up to 3m from the rear for terraced or semi-detached homes under permitted development, and up to 4m if your home is detached. Any bigger than that, and you’d need planning permission. You should also make sure your property has permitted development rights in the first place; some have had them removed or limited. This can happen for flats and maisonettes, houses in conservation areas, and new builds. When in doubt, Resi’s experts can walk you through what applies to your project in a free consultation call.
0 Rear extensions recently submitted for planning in the UK
Why choose Resi for your rear extension?
Why choose Resi for your rear extension?
Resi makes rear extensions simple. With thousands of projects behind us, we know how to design the perfect space for your home. Our experts will guide you through design, explain your financing options, make sure you’re compliant with building regulations, and they’ll even handle your planning application (with a 90%+ approval rate). We can also connect you with trusted local contractors and help you compare quotes as a free service, if you’d like. If you’re ready to bring your rear extension to life, book a free advice call with Resi today.
Research tools
Rear extension FAQs
Can I have a two storey rear extension?
Yes, a two storey rear extension is possible. Whether it would work for you depends on the layout of your house, so that’s something to chat with your architect about. Two storey extensions can be a good idea because they often mean you can create an extra bedroom upstairs, which helps with adding value to your property. You’ll need to get planning permission for a two storey extension to the rear. When considering your proposed plans, the council will look at the impact it would have on your neighbouring properties, particularly looking at light, overshadowing, and whether it affects neighbours’ privacy.
What's the difference between a rear and side extension?
A rear extension and a side extension are quite different, and it’s all to do with where the new addition to the house is built. With a rear extension, you add floor space to your house at the back, eating into your garden. With a side extension, you use dead space to the side of your house; either an alleyway or part of a driveway. It’s also possible to combine a rear and a side extension to form a wraparound extension, which can create a large footprint to rework your layout.
How much value will a rear extension add?
Adding value might not be the main reason you decide to extend your home, but it probably comes into it. The property market changes often, based on lots of factors including interest rates, where you live, and more. But for a rough estimate of how much value you could add with a rear extension, you’re looking at an average of 7.6%. If you add a two-storey rear extension that creates an extra bedroom, you could add more. For a better idea of how much you could increase your property’s worth by, try Resi’s free extension valuation calculator.
How long does a rear extension take?
Rear extensions can be really different, which means there’s no one, firm timeline to go by. But on average, any type of home extension in the UK takes between 7 and 12 months from start to finish. That breakdown includes:
- Prep: 2-4 weeks
- Design: 2-5 weeks
- Planning: 8-10 weeks (minimum)
- Technical design: 4-8 weeks (building regs and structural engineer)
- Party wall agreement: 2-12 weeks (depending on your neighbours, not everyone needs one of these)
- Tender process: 3-6 weeks (hiring a building contractor)
- Building: 2-6 months (depending on much there is to do)
Customer reviews
Read more about rear extensions
A Guide to Mid-Terrace Rear Extensions in the UK
A beginner’s guide to pitched roof rear extensions
Has the social kitchen made the living room redundant?
Do I need planning permission for a rear extension in the UK?
Book a free architectural advice call
Get answers to your pressing rear extension questions, like whether you need planning permission, how much it might cost, and whether your vision is possible where you live. Book your call today.
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