Side Return Extension Cost Calculator

A side return extension fills in the narrow alleyway (passage) that runs along the side of many Victorian and Edwardian terraced houses. It opens up the kitchen and dining area, creating a wider, brighter living space without extending into the garden.

A side return extension in London typically costs between £30,000 and £80,000 depending on length, glazing type, and whether a kitchen fitout is included. Crittall-style glazing and premium kitchen specifications push costs towards the higher end.

Many side return extensions fall under permitted development as single-storey rear extensions. However, properties in conservation areas, listed buildings, or those that have already used their PD allowance may need planning permission. We recommend checking with your local planning authority.