West Sussex
Side return extensions in West Sussex
Infilling the narrow passage beside a Victorian or Edwardian back addition. Across West Sussex we handle the whole rear extension: survey, drawings, the planning route, building control and the build. Towns we cover here include Crawley, Worthing and Bognor Regis.

In Crawley we check the boundary line and the neighbour's gutter before drawing a side return, because a few centimetres decide whether the wall goes on or beside the boundary. West Sussex has a mix of Victorian terraces near the centre and larger Edwardian and inter-war houses further out. Clay soils across much of the South East mean deeper foundations near trees, which we plan for at the survey.
How much does a side return extension cost in West Sussex?
In West Sussex, our guide for a side return extension is £2,580–£4,260 per square metre including VAT for a standard specification. South East prices run above our West Midlands baseline, mainly on labour rates and clay-soil foundations.
| Size | Guide price inc VAT |
|---|---|
| 2 m wide × 6 m deep (12 m²) | £31,000–£51,000 |
| 2.5 m wide × 7 m deep (17.5 m²) | £45,000–£74,500 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission in West Sussex?
Side return infills and the side leg of a wraparound are treated as side extensions in England: single-storey, no more than 4 metres high and no wider than half the original house. They are not permitted development in conservation areas, National Parks or National Landscapes, and a joined wraparound often needs a planning application because the side and rear rules apply together.
The Party Wall etc. Act 1996 applies in England: you serve notice two months before work to a shared wall, and one month before digging foundations within 3 metres (or 6 metres for deeper foundations) of a neighbour's building. Neighbours can agree in writing; if they dissent, surveyors agree an award.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent.
Where in West Sussex do we work?
FAQ
Questions people ask
How much space does a side return add?
Typically 8 to 18 square metres, enough to turn a galley kitchen into a kitchen-diner with an island.
Do I need my neighbour's permission?
Not their permission, but in England and Wales you must serve party wall notices, and a neighbour can consent in writing or ask for a surveyor's award.
Can I combine a side return with a rear extension?
Yes; that is a wraparound extension, and it gives the biggest open-plan room a terrace can have.
Do you cover all of West Sussex?
We cover 15 towns and districts in West Sussex, including Crawley, Worthing and Bognor Regis.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.