Side return, rear, wraparound and loft: what suits, what it costs, what to check
A Victorian terrace usually has a narrow plot, a back "outrigger" with an alley beside it (the side return), solid brick walls and a loft that suits a rear dormer. That makes four projects common: a side return extension, a rear extension, a wraparound that does both, and a loft conversion. Guide prices from our calculator: side return £40,000, rear extension £62,000, wraparound £120,000, loft dormer £45,000, all plus VAT.
| Your project | Usually | The rule |
|---|---|---|
| Side return | Fills the alley | Builds into the narrow gap beside the outrigger, so the kitchen and dining room become one wide room. Price from £40,000. |
| Rear extension | Adds depth | Pushes the back of the house into the garden, often past the end of the outrigger. Price from £62,000. |
| Wraparound | Both together | A side return and a rear extension in one, for a big open ground floor. Price from £120,000. |
| Loft conversion | Adds a bedroom | A rear dormer, often over the outrigger as well, gives a bedroom and a bathroom. Price from £45,000. |
| Type and size | Roughly | Guide price, plus VAT | Per m² | Calculator |
|---|---|---|---|---|
 Side returnSmall | 1-2m width (~6-10m²) | £40,000 – £75,000 | £4,000 – £12,500 per m² | Price it → |
| Side returnMedium | 2-3m width (~12-18m²) | £55,000 – £90,000 | £3,050 – £7,500 per m² | Price it → |
| Side returnLarge | 3m+ width (~20m²+) | £75,000 – £120,000 | £2,700 – £6,000 per m² | Price it → |
 Rear extensionSmall | 3m depth (~12m²) | £62,000 – £85,000 | £4,450 – £8,500 per m² | Price it → |
| Rear extensionMedium | 4-5m depth (~20m²) | £88,000 – £120,000 | £3,650 – £6,650 per m² | Price it → |
| Rear extensionLarge | 6m+ depth (~30m²+) | £122,000 – £165,000 | £3,200 – £5,900 per m² | Price it → |
| WraparoundSmall | Up to 20m² | £120,000 – £150,000 | £6,000 – £10,000 per m² | Price it → |
| WraparoundMedium | 20-30m² | £135,000 – £170,000 | £4,500 – £8,500 per m² | Price it → |
| WraparoundLarge | 30m²+ | £150,000 – £200,000 | £3,750 – £6,650 per m² | Price it → |
 Loft dormerBedroom Only | 1 room (~18-22m²) | £45,000 – £60,000 | £2,050 – £3,350 per m² | Price it → |
| Loft dormerBedroom + En-suite | 1 room + bathroom (~22-28m²) | £75,000 – £110,000 | £2,700 – £5,000 per m² | Price it → |
| Loft dormerFull Loft | 2 rooms + bathroom (~30-40m²) | £125,000 – £160,000 | £3,100 – £5,350 per m² | Price it → |
 MansardStandard | 1 bedroom + en-suite (~25-30m²) | £85,000 – £130,000 | £2,850 – £5,200 per m² | Price it → |
| MansardLarge | 2 bedrooms + bathroom (~32-42m²) | £135,000 – £170,000 | £3,200 – £5,300 per m² | Price it → |
| MansardFull Floor | Multiple rooms (~45-60m²) | £220,000 – £260,000 | £3,650 – £5,800 per m² | Price it → |
The same figures as our cost calculator, for the building work at a mid-range finish. They are guide prices while our launch pricing is finalised; your exact price follows a free survey. Per m² is the guide price divided by the size, rounded.
For more detail, read our extension cost guide and loft cost guide.
Old terraces have solid brick walls, so opening them up needs steel beams, designed by an engineer, with the chimney breasts carried properly. We have done this on terraces.
Many Victorian ground floors are suspended timber, and the old damp-proofing is often weak. The new extension is built to Building Regulations; the old part may need work.
Shared drains often run in the alley. Building over or near them can need the water company's agreement. We check the plans early.
You share walls with both neighbours, so a party wall agreement is usually needed, and a neighbour's light can matter on a tight plot.
Many Victorian streets in south-west London are in conservation areas, where the rules for side and two-storey extensions are tighter. See our planning guide.
Original features such as cornices, fireplaces, sash windows and floors can be kept or matched. We say what is possible on the survey.
Often permitted development if it is single storey, no higher than 4 m and under half the width of the house, though many London side returns still go through a planning application. A rear dormer is often permitted development: up to 40 m³ of extra roof space on a terrace, set back from the eaves and not facing the street. See our planning guides for extensions and lofts.
The same figures as our cost calculator, for the building work at a mid-range finish. They are guide prices while our launch pricing is finalised; your exact price follows a free survey. General guidance, not legal advice.
Rear extension & full refurbishment
A strategic rear extension and full interior refurbishment. By opening up the rear elevation, we created a seamless connection between the living space and the garden, with a roof lantern and gabled glazing bringing light deep into the plan.
Rear & loft extension, full refurbishment
A coordinated rear extension and loft conversion alongside a full interior refurbishment, making the most of vertical and horizontal space on a compact urban plot.
Rear & loft extension, full refurbishment
A rear and loft extension that overhauled the scale of a terrace home, extending out and up while modernising the whole interior.
A Victorian terrace usually has a narrow plot, a back "outrigger" with an alley beside it (the side return), solid brick walls and a loft that suits a rear dormer. That makes four projects common: a side return extension, a rear extension, a wraparound that does both, and a loft conversion. Guide prices from our calculator: side return £40,000, rear extension £62,000, wraparound £120,000, loft dormer £45,000, all plus VAT.
A side return starts from £40,000, a rear extension from £62,000, a wraparound from £120,000, plus VAT. The size decides the rest.
It fills the alley beside the back of a terrace (the "side return"), so the kitchen and dining room widen into one room. Often it is built together with a rear extension, which is called a wraparound.
Usually yes. A rear dormer, often built over the outrigger too, gives a bedroom and a bathroom. A rear dormer is often permitted development: up to 40 m³ of extra roof space on a terrace, set back from the eaves and not facing the street.
Often permitted development if it is single storey, no higher than 4 m and under half the width of the house, though many London side returns still go through a planning application. Guidance for homes in England, not advice. A conservation area, a listed building or an Article 4 direction changes the rules, and we confirm what applies on survey.
Usually, yes. On a terrace you share walls with both neighbours, and building on or next to them normally needs an agreement. We explain it on the survey.
Book a free survey. We come and look at the house, then give you a written price. No charge, no obligation.
