How to plan a side return extension

What is a side return extension?

Many terraced and semi-detached houses, especially Victorian builds, have an outdoor passage running alongside the kitchen. This alley, called a side return, is often wasted and unused. A side return extension is when you extend the property into this space.

Do you need planning permission for a side return extension?

You don’t always need full planning permission for a side return extension. Permitted Development (PD) allows a single-storey structure up to four metres high and measuring up to half the original house across. If the extension is within two metres of the boundary, the eaves’ height will need to be under three metres.
Building this type of extension on a terraced house is more likely to need planning permission, since it’s deemed as both a side and rear extension.

Do you need your neighbour's permission for an extension?

Always design with consideration for your neighbours, making sure the new structure doesn’t block out their light. Visit planningportal.co.uk to find out about the dos and don’ts of single-storey extensions.

If you’re creating a new shared boundary wall or digging within three metres of your neighbour’s house, you’ll need to get a Party Wall Notice two months before work starts. If your neighbours give written consent within 14 days, you won’t need a full party wall agreement, which can cost £700 to £900 to get drawn up by a surveyor.

How much will a side return extension cost?

Expect to pay from £1,200 to £1,500 per sq m, although this can be 15-20 per cent higher in London. You can save money by hiring a builder to construct the shell and project managing the various trades such as electricians, plumbers and plasterers. Bi-fold doors can be pricey, so cut costs with a picture window and glazed door instead.