Horsham, West Sussex
Side return extension in Horsham
Infilling the narrow passage beside a Victorian or Edwardian back addition. If you live in Horsham and want to know what a side return extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Horsham is covered from our West Sussex round, including RH12. In Horsham 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.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a side return extension cost in Horsham?
In Horsham, 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 for a side return extension in Horsham?
The planning route for a side return extension in Horsham is set by England's householder rules and your council.
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. At the first visit we measure what is there now and tell you which route fits: permitted development, prior approval or a planning application.
What are homes in Horsham like to extend?
Horsham 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 a side return extension in Horsham comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Paperwork handled
Planning, prior approval or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Side return extensions near Horsham
Neighbouring places we cover include Broadfield (5.8 miles) and Crawley (7.2 miles).
- Side return extension in Broadfield
- Side return extension in Crawley
- Side return extension in Cranleigh
- Side return extension in Horley
- Side return extension in Hurstpierpoint
Other work in Horsham:
FAQ
Side return extension questions in Horsham
Can you match the brick or stone on my Horsham house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
Where does the drainage go?
Side passages often carry the soil and rainwater pipes. We survey them first and reroute them under the new floor where needed.
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Do I need planning permission for a rear extension in Horsham?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.