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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£43,660
Side return extension near Birmingham£39,430
Side return extension near Glasgow£42,220
Side return extension near Leeds£40,240
Side return extension near Liverpool£39,880
Side return extension near Sheffield£44,200
Side return extension near Edinburgh£43,030
Side return extension near Manchester£40,240
Side return extension near Belfast£33,490
Side return extension near Bristol£42,040
Side return extension near Leicester£38,440
Side return extension near Cardiff£38,710
Side return extension near Coventry£38,980
Side return extension near Bradford£39,070
Side return extension near Nottingham£40,690
Side return extension near Newcastle Upon Tyne£39,970
Side return extension near Brighton and Hove£41,590
Side return extension near Derby£39,520
Side return extension near Hull£39,070
Side return extension near Plymouth£39,700
Side return extension near Stoke-on-Trent£39,340
Side return extension near Southampton£40,870
Side return extension near Northampton£40,600
Side return extension near Wolverhampton£39,070
Side return extension near Luton£43,840
Side return extension near Portsmouth£41,320
Side return extension near Reading£42,940
Side return extension near Norwich£37,000
Side return extension near Milton Keynes£42,670
Side return extension near Bournemouth£42,130
Side return extension near Aberdeen£46,180
Side return extension near Peterborough£44,200
Side return extension near Bolton£38,710
Side return extension near Swindon£40,420
Side return extension near Southend-on-Sea£41,320
Side return extension near Warrington£38,980
Side return extension near Oxford£42,850
Side return extension near Swansea£39,610
Side return extension near Sunderland£41,590
Side return extension near Slough£43,660
Side return extension near Kingswood£42,130
Side return extension near Telford£40,690
Side return extension near Cambridge£43,390
Side return extension near Ipswich£40,150
Side return extension near Blackpool£37,810
Side return extension near Middlesbrough£40,150
Side return extension near Dundee£44,650
Side return extension near Huddersfield£39,160
Side return extension near York£39,610
Side return extension near Poole£41,500
Side return extension near Watford£44,020
Side return extension near Newport£39,970
Side return extension near Colchester£39,700
Side return extension near Exeter£38,890
Side return extension near Blackburn£41,230
Side return extension near Crawley£41,950
Side return extension near Gloucester£40,060
Side return extension near Stockport£40,060
Side return extension near Basingstoke£43,660
Side return extension near Basildon£41,590
Side return extension near Cheltenham£41,500
Side return extension near Gateshead£40,060
Side return extension near Worthing£41,590
Side return extension near Rochdale£38,890
Side return extension near Oldham£39,520
Side return extension near Chelmsford£42,220
Side return extension near Birkenhead£39,880
Side return extension near Maidstone£41,950
Side return extension near Gillingham£41,770
Side return extension near Salford£40,420
Side return extension near Solihull£39,790
Side return extension near St Helens£39,160
Side return extension near Worcester£38,620
Side return extension near Lincoln£39,880
Side return extension near West Bromwich£39,430
Side return extension near Eastbourne£41,050
Side return extension near Wakefield£40,600
Side return extension near Wythenshawe£39,610
Side return extension near Bedford£44,020
Side return extension near Hemel Hempstead£43,300
Side return extension near Preston£38,710
Side return extension near Stevenage£44,380
Side return extension near Southport£36,820
Side return extension near Bath£41,410
Side return extension near Harlow£44,920
Side return extension near Sutton Coldfield£39,520
Side return extension near Darlington£38,980
Side return extension near Chester£38,800
Side return extension near Hastings£41,140
Side return extension near Nuneaton£39,250
Side return extension near Halifax£40,870
Side return extension near Hartlepool£40,240
Side return extension near Aylesbury£43,300
Side return extension near Doncaster£40,420
Side return extension near Grimsby£41,140
Side return extension near Wallasey£40,240
Side return extension near Londonderry£36,100
Side return extension near Stockton-on-Tees£39,340
Side return extension near Weston-super-Mare£41,770
Side return extension near High Wycombe£43,480
Side return extension near Ashford£42,040
Side return extension near Redditch£40,060
Side return extension near Wigan£38,710
Side return extension near Scunthorpe£37,630
Side return extension near Bury£38,800
Side return extension near Paisley£42,310
Side return extension near Bracknell£44,740
Side return extension near Burnley£38,710
Side return extension near Rugby£39,160
Side return extension near Guildford£45,820
Side return extension near Carlisle£37,360
Side return extension near Chatham£41,860
Side return extension near East Kilbride£41,230
Side return extension near Newcastle-under-Lyme£39,520
Side return extension near Chesterfield£42,130
Side return extension near Burton upon Trent£41,950
Side return extension near Tamworth£44,920
Side return extension near Shrewsbury£41,410
Side return extension near Woking£43,930
Side return extension near St Albans£44,920
Side return extension near Harrogate£39,250
Side return extension near Crewe£39,160
Side return extension near South Shields£42,130
Side return extension near Craigavon£35,290
Side return extension near Stafford£39,160
Side return extension near Rotherham£42,130
Side return extension near Barnsley£40,780
Side return extension near Lowestoft£36,730
Side return extension near Walsall£39,340
Side return extension near Gosport£41,140
Side return extension near Dartford£43,570
Side return extension near Bognor Regis£41,230
Side return extension near Corby£38,260
Side return extension near Paignton£38,980
Side return extension near Maidenhead£43,570
Side return extension near Rochester£41,860
Side return extension near Ellesmere Port£38,260
Side return extension near Loughborough£42,580
Side return extension near Dudley£39,250
Side return extension near Bangor£35,470
Side return extension near Dewsbury£41,050
Side return extension near Mansfield£42,580
Side return extension near Margate£37,720
Side return extension near Kettering£40,330
Side return extension near Cannock£39,430
Side return extension near Sale£40,150
Side return extension near Taunton£40,780
Side return extension near Runcorn£39,520
Side return extension near Farnborough£43,570
Side return extension near Tynemouth£42,130
Side return extension near Hereford£39,520
Side return extension near Halesowen£39,430
Side return extension near Widnes£38,800
Side return extension near Huyton with Roby£40,600
Side return extension near Scarborough£40,060
Side return extension near Gravesend£42,400
Side return extension near Bebington£38,980
Side return extension near Kidderminster£37,810
Side return extension near Stourbridge£39,070
Side return extension near Barry£38,620
Side return extension near Smethwick£39,340
Side return extension near Dunfermline£44,650
Side return extension near Livingston£42,040
Side return extension near Weymouth£42,400
Side return extension near Brentwood£42,040
Side return extension near Barrow-in-Furness£37,360
Side return extension near Hamilton£38,440
Side return extension near Canterbury£39,880
Side return extension near Wellingborough£41,590
Side return extension near Sittingbourne£41,140
Side return extension near Macclesfield£40,330
Side return extension near Bootle£40,150
Side return extension near Carlton£40,780
Side return extension near Esher£43,660
Side return extension near Clacton-on-Sea£39,880
Side return extension near Lancaster£37,990
Side return extension near Beeston£40,240
Side return extension near Banbury£40,510
Side return extension near Torquay£39,070
Side return extension near Folkestone£39,970
Side return extension near Kingswinford£38,890
Side return extension near Bloxwich£39,250
Side return extension near Bridgend£37,000
Side return extension near Welwyn Garden City£43,120
Side return extension near Lisburn£33,760
Side return extension near Leamington Spa£38,080
Side return extension near Washington£41,590
Side return extension near Tunbridge Wells£42,220
Side return extension near Kirkcaldy£45,640
Side return extension near Hinckley£39,160
Side return extension near Durham£43,030
Side return extension near Cumbernauld£40,060
Side return extension near Wokingham£44,200
Side return extension near Horsham£42,850
Side return extension near Crosby£39,070
Side return extension near Yeovil£45,460
Side return extension near Thundersley£41,590
Side return extension near Altrincham£39,520
Side return extension near Willenhall£39,250
Side return extension near Christchurch£41,590