Side Return Extensions

What a side return actually is

The alley beside the back addition, built out to the boundary and roofed.

Victorian and Edwardian terraces were built to a standard plan: two rooms at the front, and a narrower rear wing, the outrigger, running back into the garden with a strip of open ground beside it. That strip is the side return. It is typically between 1.5 and 2.5 metres wide, it usually holds a drain, a few pots and a bicycle, and it does nothing for the house at all.

Building across it and removing the outrigger’s side wall turns two narrow rooms into one wide one. A kitchen that was 2.2 metres wide becomes 4.2 metres wide, and at that width it stops being a corridor with units down one side and becomes a room that a family can be in together.

The point worth understanding is that the value is not floor area. A side return typically adds only 10 to 15 square metres, which is small for the money. What it adds is proportion. The rooms in a terrace are long and thin because the plot is long and thin, and this is the only move available that makes them wide.

Many side returns are combined with a rear extension coming off the back of the outrigger, which produces a wrap around. That is a bigger job with a bigger result, but the side return on its own is frequently enough, and it is considerably cheaper. Out, up or into the roof is the first decision.

Access, and why terraces cost more per metre

Everything goes through the house. That is the whole story.

A terraced house has no side gate. Every barrow of spoil comes out through the hallway, and every pack of blocks, every bag of sand and every length of steel goes in the same way, on boards, past your stairs.

That is slower, it needs far more protection, and it changes what plant can be used. A mini digger that would do a foundation in a day on a semi cannot get into a terrace back garden, so a proportion of the dig is by hand. Concrete arrives by pump or by barrow rather than straight off the wagon.

This is why side returns are typically the most expensive extension type per square metre despite being structurally simple. It is not the building, it is the logistics of building it, and any quote that prices a terrace as though it had side access has not visited the property.

The practical consequences worth knowing: a skip needs a permit from the council to sit on the road, working hours are constrained, and the front of the house is a working entrance for several weeks. We protect floors and stairs as a matter of course rather than as an extra, because the alternative is repairing them at the end.

Planning: usually permitted, with real exceptions

Most side returns are permitted development. Terraces have more that can remove that.

A side return extension is generally treated as a rear extension for permitted development purposes where it comes off the back of the house, and the standard depth limits apply, measured from the original rear wall.

The word original does the usual work. Many terraces have already been extended once, and that depth counts against your allowance even though a previous owner built it. Where a side return is filling in beside an existing outrigger rather than extending beyond the original rear wall, the position is often more favourable, but it needs checking rather than assuming.

Height matters more here than on a wide plot. Any part of the extension within two metres of a boundary has its eaves capped lower, and on a side return the whole structure is within two metres of a boundary by definition. That eaves limit frequently determines the roof design and sometimes the internal ceiling height.

What removes permitted development entirely: flats and maisonettes, and an Article 4 direction. Listing does not remove it, but it adds listed building consent as a separate requirement. What restricts it: a conservation area, where side extensions generally lose permitted status and cladding and materials need consent. Colchester’s conservation areas include the historic core and the Dutch Quarter, both of which contain exactly the terraced stock that suits a side return, so this is a live question rather than a theoretical one.

Whatever the answer, apply for a Lawful Development Certificate where the work is permitted development. It is the document that proves the extension was lawful when a buyer’s solicitor asks in ten years.

Building Regulations

Separate from planning, and the part that decides whether the room works.

Part A for structure and the beams over both openings. Part B for escape windows to habitable rooms. Part C for damp proofing, the membrane under the slab and, critically on this job, cavity trays where the new roof abuts the neighbour’s wall and where it abuts your own. Part F for ventilation. Part H for drainage. Part K for glazing and level changes. Part L for insulation and glazed area.

Cavity trays deserve a specific mention on a side return, because the new roof abuts a wall on the boundary for its entire length. That junction carries a great deal of water and it is the most common source of a damp complaint two winters later. It is lead or a properly specified alternative, dressed correctly, with the tray above it and weep holes where they belong.

We use a full plans submission rather than a building notice on anything with a structural opening. The drawings and the engineer’s calculations are checked before work starts and you receive a decision notice, which removes almost all the risk of an expensive disagreement halfway through. We notify Colchester City Council Building Control and manage the inspections to your completion certificate.

What a side return costs

The highest rate per square metre of any extension type, for reasons that have nothing to do with the building.

Indicative and current at the review date below, not a quotation.

A side return extension typically runs £2,600 to £3,400 per square metre for the shell and a standard finish. On a 14 square metre side return that is roughly £36,000 to £48,000 before the exclusions. The rate is higher than a rear extension on a semi because of access, the party wall work, and the drainage that is always in the way.

That includes groundworks and foundations to the specified depth, drainage alterations, structure including the steels and any posts and pads, external walls and insulation, roof and rooflights, glazing at the garden end, plastering, first and second fix carpentry, electrics and plumbing to a standard specification, and making good.

It excludes: VAT, kitchen units and appliances, flooring, decoration, professional fees for drawings and structural calculations, planning and Building Control fees, party wall surveyor fees, which on a side return are near certain rather than possible, build over agreement fees, service diversions, and anything unforeseeable found once the ground is open.

Budget for the party wall properly. Where a neighbour dissents and surveyors are appointed, the fees are real money and they are payable by you. It is not a reason to avoid the work, it is a reason to know the number before you start.

Where side returns work in Colchester

The stock that suits this job sits in specific streets, and some of it is in a conservation area.

The terraced housing that has a side return to fill is concentrated in the Victorian and Edwardian expansion of the town: New Town and the streets running off Military Road and Magdalen Street, the roads off Maldon Road, and pockets around Barrack Street and the station. These are the classic two up two down and three bedroom terraces with a rear outrigger and a narrow alley beside it.

The Dutch Quarter and the historic core are different. The property there is older, frequently timber framed, often listed, and almost entirely within a conservation area. A side return in that context is a design and consent exercise rather than a standard job, and listed building consent is a separate decision from planning permission. It is entirely doable and it takes longer.

Wivenhoe has a good stock of terraced property near the waterfront, much of it in the conservation area there. Brightlingsea and parts of Manningtree are similar.

What all of these share is the access constraint, the Victorian drainage running exactly where you want to build, and boundary walls of uncertain construction. What they also share is that the result transforms the house more completely than any other extension type, because the problem being solved is proportion rather than area.

On estate housing from the 1960s onwards there is usually no side return to fill, because those houses were built with the plan already square. If you have side access rather than a side return, the equivalent move is a side extension, which is a different job with different rules. A detached house rarely has the problem at all.