Side Return Extension Ideas for Southampton Homes
Side return extension ideas come up on almost every survey visit we do in Southampton's Victorian and Edwardian streets. Walk down any road in Shirley, Portswood or Freemantle and you'll see the same layout: a long, dark galley kitchen at the back, with a narrow strip of alley beside it that mostly holds the bins. Infilling that strip is one of the best-value ways to get a proper kitchen-diner without giving up much garden.
Below are the ideas our extension team is putting into side returns around Southampton this year, what they do for the room, and where the money and the planning questions really sit.
Start with the roof, because that's where the light comes from
A side return sits between your house and the neighbour's wall, so you rarely get much light from the side. Nearly all of it comes from above, which makes the roof the biggest design decision on the job.
Fully glazed pitched roof. The brightest option and the most dramatic. It needs decent solar-control glass, or a south-facing kitchen turns into a greenhouse by June.
Solid roof with a run of frameless rooflights. Our most requested choice. You keep most of the light, the room holds its heat better in winter, and it costs noticeably less.
Slate or tiled pitch with one long rooflight on the boundary edge. Tidy from the bedrooms upstairs, which matters more than people expect, because you'll be looking down on it every day.
If a first-floor window looks straight down onto the new roof, think about how the top of it looks, not just the ceiling underneath. Lead flashings, gutters and rooflight frames are all on show from up there.
Side return extension ideas inside the room
Once the light's sorted, the layout tends to follow. These are the touches we see working best in Southampton terraces:
Kitchen along the party wall, dining by the glass. Sink, units and appliances go against the solid boundary wall, which leaves the bright side and the garden end for the table.
Exposed brick. Once the old flank wall comes down, the retained brickwork can be cleaned up and left on show. It suits the age of the house and saves on plastering.
One wide slider instead of bifolds. Bifolds still sell, but more of our clients now go for a single large sliding door with slim frames. Fewer mullions, better view of the garden.
Underfloor heating. With this much glass, wall space for radiators vanishes fast. We fit wet or electric underfloor heating in most side returns we build.
A level floor through to the old kitchen. Small detail, big difference. Getting rid of the step between old and new makes it read as one room rather than an add-on.
The structural bit nobody sees
Taking out the side wall of the back addition means the house above needs new support, usually a steel beam running the length of the opening, sometimes with a goalpost frame where it meets the main house. A structural engineer designs it and building control signs it off. We covered the detail in our guide to RSJ installation in Southampton, but the short version is that it's routine when it's planned properly and messy when it isn't.
Party walls come into it too. A side return usually builds right up to the boundary, so the Party Wall etc. Act 1996 applies and your neighbour needs formal notice before work starts. We build that time into the programme from the first meeting, so it doesn't catch anyone out on start day.
Do you need planning permission for a side return in Southampton?
Often you don't. A single-storey side extension can come under permitted development if it's no more than 4 metres high, no wider than half the width of the original house, and the eaves stay under 3 metres where it's within 2 metres of the boundary. Most side returns sit well inside those limits.
There are exceptions. Side extensions aren't permitted development in conservation areas, and Southampton has a few with terraced streets, including parts of Banister Park and the Portswood Residents' Gardens. A wraparound design, where the infill turns the corner and extends out the back in one L-shape, is treated differently again and usually needs a full application. Whichever route you're on, you'll still need Building Regulations approval, and if you're relying on permitted development it's worth getting a Lawful Development Certificate so you have it in writing when you come to sell.
What does a side return extension cost in Southampton?
Side returns cost more per square metre than a straightforward rear extension, because access down the alley is tight and so much of the work is joining new to old. Based on current south-coast rates, a Complete Builds side return with a solid roof and rooflights typically comes in at around £2,650 to £3,350 per square metre. A typical 12m² infill works out at roughly £32,000 to £40,000, before the new kitchen and any design or engineer's fees.
Choose a fully glazed roof and you're looking at nearer £3,350 to £4,200 per square metre, mostly down to the glass. Uneven floors, old clay drains running under the alley or a chimney breast in the way will all push the number up, and that's exactly why we survey before we quote. On site, most side returns take 8 to 12 weeks, depending on the roof and the groundworks.
Related reading
Thinking about your own side return?
If you're in Southampton, or nearby in Eastleigh, Chandler's Ford or Totton, we'll come out, measure up, check the structure, drains and boundary, and give you a clear written price with the planning route spelled out. Book a survey visit with Complete Builds and we'll take it from there.
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