By Emily Rivers
Last updated 25th February 2026

Side return extension cost guide

If you need some extra space in your home but you don’t want to eat into your garden, have you considered a side return extension? If you live in a terraced house or another type of property that has a small amount of space at the side that goes widely unused, this type of extension could be the perfect answer for you. But how much does it cost?

The average cost of a side return extension is £46,000 excluding VAT. Expect it to take anywhere up to 4 months to complete, assuming you have any planning or party wall applications agreed already. But the size of the extension, what you want to use the extension for and the complexity of the job will impact the final cost. Make sure you get a range of quotes from different size companies to ensure you’re getting a fair price for your side return extension.

What is a side return extension?

A side return extension makes use of the space that you commonly see at the side of terraced and semi-detached houses. They’re small alleys that people often use for storing bikes and bins, but otherwise go unused - so it’s the perfect way to add space to your home without eating into your garden.

Often, side return extensions are the ideal solution to making your kitchen bigger, but that means knocking through the external supporting wall, which will increase the cost. Some people opt to have the side return extension added to the outside wall, making it more like a lean-to conservatory.

Cost to build a side return extension

Will I need building planning permission?

Usually, you won’t need planning permission for a side return extension as it falls under permitted development rights. There are a few criteria that your side return extension needs to meet to be within permitted development rights:

  • It must not exceed more than 4 metres high
  • It must be single storey
  • It must be no more than half the width of the original house

It’s also worth bearing in mind how much your property has been extended in the past. You may only extend up to half of the area around the original house.

Conservation areas

Another thing to watch out for is whether you live in a conservation area. If you do, you’ll need to apply for planning permission. Since side return extensions are common in Victorian terraced houses, there’s a higher chance that your home is in a conservation area. Make sure you do research into this before engaging any tradespeople.

Party Wall Act

You’ll also need to consider the Party Wall Act. This is a piece of legislation that requires that you notify your adjoining neighbour of any ‘notifiable’ works that you wish to undertake. The adjoining neighbour may then consent or dissent to the notice. It’s worth speaking to your neighbours about your side return extension, well in advance of serving any notices, so they know what to expect.

Uses for your side return extension

Kitchen

The most common use for side return extensions is to make the kitchen larger. Lots of terraced houses have narrow galley kitchens and even a narrow side return extension can make the kitchen feel much larger and make it easier to move around in.

Lots of people opt to have high ceilings and roof lights in the extension to improve the light and general feel of the kitchen. People that have the room for a larger side return kitchen extension may also opt to turn it into a kitchen diner to make use of the space.

Shower room

Homes with one bathroom may use their side return extension to add an extra shower room to the property. Bathroom designers are used to maximising space in their designs, so speak to one to see what they suggest for adding a shower room into your side return extension.

Cost breakdown for a side return extension

Although a relatively small type of extension, there is still a lot to think about when it comes to building a side return extension. Here’s a breakdown of the costs involved and the percentage you can expect to spend on each area:

Cost breakdown of a side return extension as a percentage

Area

Percentage of budget

Architect

4%

Admin fees

1%

Structural engineers

3%

Surveyors

2%

Tradespeople

30%

Materials

20%

Fittings

5%

Glazing

15%

VAT

20%

If an average side return extension costs £46,000 excluding VAT, you should expect to spend around £18,500 on admin fees, fittings and materials. Labour and service costs will vary depending on your location, with London seeing the highest prices.

Is it worth building a side return extension?

Some people wonder whether it’s worth building a side return extension, especially if it’s narrow. The main thing to consider is how much value it will add to your life - and to the property itself.

Side return extensions give you more room without sacrificing garden space, and will often improve the indoor-outdoor connection of your property. These benefits will add value to your property as buyers look for homes that have made the best use of the space available, rather than taking the most expensive option.

Although side return extensions are often small, they can improve the quality of your life in your home by much more than you think. Adding that extra bit of space to your kitchen to allow you to move around more freely or reducing bathroom queues in the morning can make a huge impact on your family’s wellbeing. It might even mean that you decide to stay in your home longer than you originally planned, which makes it even more cost-effective.

Get competitive quotes from builders near you

There are lots of different costs involved in a side return extension, so make sure you get a range of quotes from builders, architects and structural engineers to get an accurate representation of how much a side return extension will set you back.

Post a job on HaMuch to get quotes from reputable builders in your area.


Estimates for common extension builder jobs;

Rates for other trades

Side return extension cost in the UK
Side return extension cost in the UK (excluding VAT or callout charges)
Location in UKSide return extension cost
Side return extension near London£40,330
Side return extension near Birmingham£36,730
Side return extension near Glasgow£38,890
Side return extension near Leeds£37,360
Side return extension near Liverpool£37,000
Side return extension near Sheffield£41,050
Side return extension near Edinburgh£40,240
Side return extension near Manchester£37,270
Side return extension near Belfast£30,880
Side return extension near Bristol£38,980
Side return extension near Leicester£35,920
Side return extension near Cardiff£36,100
Side return extension near Coventry£36,370
Side return extension near Bradford£36,640
Side return extension near Nottingham£37,540
Side return extension near Newcastle Upon Tyne£37,450
Side return extension near Brighton and Hove£38,710
Side return extension near Derby£37,270
Side return extension near Hull£36,550
Side return extension near Plymouth£36,640
Side return extension near Stoke-on-Trent£36,640
Side return extension near Southampton£38,350
Side return extension near Northampton£37,180
Side return extension near Wolverhampton£36,460
Side return extension near Luton£40,600
Side return extension near Portsmouth£38,440
Side return extension near Reading£39,700
Side return extension near Norwich£34,930
Side return extension near Milton Keynes£39,340
Side return extension near Bournemouth£38,800
Side return extension near Aberdeen£41,680
Side return extension near Peterborough£41,140
Side return extension near Bolton£36,370
Side return extension near Swindon£37,630
Side return extension near Southend-on-Sea£38,350
Side return extension near Warrington£36,640
Side return extension near Oxford£39,700
Side return extension near Swansea£36,730
Side return extension near Sunderland£38,800
Side return extension near Slough£40,420
Side return extension near Kingswood£39,070
Side return extension near Telford£36,730
Side return extension near Cambridge£40,060
Side return extension near Ipswich£37,180
Side return extension near Blackpool£35,470
Side return extension near Middlesbrough£37,180
Side return extension near Dundee£40,600
Side return extension near Huddersfield£36,910
Side return extension near York£36,640
Side return extension near Poole£38,260
Side return extension near Watford£40,510
Side return extension near Newport£37,000
Side return extension near Colchester£37,000
Side return extension near Exeter£36,280
Side return extension near Blackburn£38,350
Side return extension near Crawley£39,430
Side return extension near Gloucester£37,090
Side return extension near Stockport£37,180
Side return extension near Basingstoke£39,880
Side return extension near Basildon£38,800
Side return extension near Cheltenham£38,620
Side return extension near Gateshead£37,540
Side return extension near Worthing£39,070
Side return extension near Rochdale£35,920
Side return extension near Oldham£36,820
Side return extension near Chelmsford£39,160
Side return extension near Birkenhead£37,000
Side return extension near Maidstone£39,250
Side return extension near Gillingham£38,710
Side return extension near Salford£37,270
Side return extension near Solihull£36,370
Side return extension near St Helens£36,550
Side return extension near Worcester£36,460
Side return extension near Lincoln£37,720
Side return extension near West Bromwich£36,550
Side return extension near Eastbourne£38,170
Side return extension near Wakefield£37,180
Side return extension near Wythenshawe£36,820
Side return extension near Bedford£39,970
Side return extension near Hemel Hempstead£39,790
Side return extension near Preston£35,920
Side return extension near Stevenage£40,510
Side return extension near Southport£34,480
Side return extension near Bath£38,800
Side return extension near Harlow£41,230
Side return extension near Sutton Coldfield£37,180
Side return extension near Darlington£36,460
Side return extension near Chester£36,370
Side return extension near Hastings£37,810
Side return extension near Nuneaton£35,920
Side return extension near Halifax£37,900
Side return extension near Hartlepool£37,360
Side return extension near Aylesbury£40,240
Side return extension near Doncaster£37,720
Side return extension near Grimsby£37,630
Side return extension near Wallasey£37,270
Side return extension near Londonderry£33,940
Side return extension near Stockton-on-Tees£37,090
Side return extension near Weston-super-Mare£38,440
Side return extension near High Wycombe£40,330
Side return extension near Ashford£38,170
Side return extension near Redditch£36,640
Side return extension near Wigan£36,010
Side return extension near Scunthorpe£35,740
Side return extension near Bury£36,280
Side return extension near Paisley£39,070
Side return extension near Bracknell£41,320
Side return extension near Burnley£36,370
Side return extension near Rugby£36,010
Side return extension near Guildford£41,950
Side return extension near Carlisle£34,750
Side return extension near Chatham£38,800
Side return extension near East Kilbride£37,630
Side return extension near Newcastle-under-Lyme£36,730
Side return extension near Chesterfield£39,250
Side return extension near Burton upon Trent£38,620
Side return extension near Tamworth£41,590
Side return extension near Shrewsbury£36,280
Side return extension near Woking£40,420
Side return extension near St Albans£40,780
Side return extension near Harrogate£36,730
Side return extension near Crewe£36,820
Side return extension near South Shields£38,710
Side return extension near Craigavon£34,300
Side return extension near Stafford£36,730
Side return extension near Rotherham£39,250
Side return extension near Barnsley£37,900
Side return extension near Lowestoft£35,110
Side return extension near Walsall£36,550
Side return extension near Gosport£38,350
Side return extension near Dartford£40,330
Side return extension near Bognor Regis£38,170
Side return extension near Corby£36,370
Side return extension near Paignton£37,090
Side return extension near Maidenhead£40,240
Side return extension near Rochester£38,800
Side return extension near Ellesmere Port£36,370
Side return extension near Loughborough£38,800
Side return extension near Dudley£36,370
Side return extension near Bangor£32,500
Side return extension near Dewsbury£37,540
Side return extension near Mansfield£39,160
Side return extension near Margate£35,830
Side return extension near Kettering£37,450
Side return extension near Cannock£36,640
Side return extension near Sale£37,360
Side return extension near Taunton£37,720
Side return extension near Runcorn£36,820
Side return extension near Farnborough£40,510
Side return extension near Tynemouth£38,710
Side return extension near Hereford£37,360
Side return extension near Halesowen£36,820
Side return extension near Widnes£36,370
Side return extension near Huyton with Roby£37,900
Side return extension near Scarborough£36,100
Side return extension near Gravesend£39,430
Side return extension near Bebington£36,100
Side return extension near Kidderminster£35,470
Side return extension near Stourbridge£36,460
Side return extension near Barry£36,010
Side return extension near Smethwick£36,550
Side return extension near Dunfermline£40,150
Side return extension near Livingston£38,620
Side return extension near Weymouth£38,890
Side return extension near Brentwood£39,250
Side return extension near Barrow-in-Furness£34,570
Side return extension near Hamilton£35,920
Side return extension near Canterbury£37,990
Side return extension near Wellingborough£38,350
Side return extension near Sittingbourne£38,530
Side return extension near Macclesfield£36,910
Side return extension near Bootle£37,180
Side return extension near Carlton£37,450
Side return extension near Esher£40,330
Side return extension near Clacton-on-Sea£36,730
Side return extension near Lancaster£35,650
Side return extension near Beeston£37,360
Side return extension near Banbury£38,170
Side return extension near Torquay£37,180
Side return extension near Folkestone£37,270
Side return extension near Kingswinford£36,190
Side return extension near Bloxwich£36,550
Side return extension near Bridgend£34,300
Side return extension near Welwyn Garden City£39,610
Side return extension near Lisburn£31,510
Side return extension near Leamington Spa£35,920
Side return extension near Washington£38,890
Side return extension near Tunbridge Wells£39,520
Side return extension near Kirkcaldy£41,770
Side return extension near Hinckley£36,010
Side return extension near Durham£39,880
Side return extension near Cumbernauld£37,270
Side return extension near Wokingham£40,690
Side return extension near Horsham£39,340
Side return extension near Crosby£36,100
Side return extension near Yeovil£40,780
Side return extension near Thundersley£38,890
Side return extension near Altrincham£36,640
Side return extension near Willenhall£36,550
Side return extension near Christchurch£38,890