West Sussex · RH12, RH13
Extensions in Horsham
A home extension adds new floor space to an existing property — commonly a rear or side-return kitchen extension, a wraparound, or a first-floor addition — and typically involves planning or permitted development approval, Building Regulations, and coordination of groundworks, structure, roofing and internal finishing.
In Horsham, that covers Roffey, Holbrook, Littlehaven, Denne, Trafalgar, Broadbridge Heath, Southwater, Warnham, Colgate. Horsham's town centre retains a historic core of timber-framed and Georgian buildings around the Carfax and Causeway, surrounded by Victorian villas, interwar suburbs and newer developments on the town's edges. The surrounding villages and countryside sit close to the South Downs, which shapes both the property styles and the planning context for extension and renovation work.
Coverage
Areas we cover in Horsham for extensions
Property styles in Horsham
Horsham has a strong stock of period cottages and Victorian villas in and around the town centre, alongside 20th-century family housing in the surrounding estates and larger detached homes in the outlying villages. Extension and loft conversion potential varies significantly between the historic core and the more recent suburbs.
Planning considerations
Horsham District Council is the local planning authority. The town centre, including the Causeway, is a conservation area with a number of listed buildings, meaning alterations to visible elevations, windows and materials are more tightly controlled. Some outlying villages also have their own conservation area designations, which we check before advising on likely planning routes.
How it works
Our extensions process
- 01
Feasibility and survey
Assessing what is achievable on the plot, including boundary conditions, trees, drainage and neighbouring properties.
- 02
Design
Developing layout and elevations that work with the existing house, in scale and materials.
- 03
Planning route
Establishing whether the extension falls under permitted development or requires a full planning application, and submitting accordingly.
- 04
Party wall matters
Serving party wall notices where the extension is near a boundary, ahead of any groundworks starting.
- 05
Construction
Groundworks, structure, roof, and first fix through to decoration, with the existing house kept weathertight throughout.
- 06
Completion
Building Control sign-off, snagging list and handover.
Also in this area
Other services we provide in Horsham
Nearby coverage
Extensions in nearby areas
FAQs
Extensions in Horsham: FAQs
Do you provide extensions across all of Horsham?
Yes, we cover the RH12 and RH13 postcode areas in full, including Roffey, Holbrook, Littlehaven, Denne, Trafalgar, Broadbridge Heath, Southwater, Warnham, Colgate.
Do I need planning permission for a rear extension?
Many single-storey rear extensions fall under permitted development if they meet size, height and boundary criteria. Larger extensions, those on designated land, or properties where permitted development rights have been removed, need a full planning application. We assess this during the feasibility stage.
What is a party wall notice and do I need one?
If your extension involves work at or near a shared boundary, the Party Wall etc. Act 1996 usually requires you to notify your neighbour before work starts. We flag this during design so notices can be served in good time.
Is Horsham town centre a conservation area?
Yes, the historic core around the Carfax and Causeway is a conservation area with a number of listed buildings, which affects what changes can be made without planning permission or listed building consent.
Get a quote for extensions in Horsham
Tell us about the property and what you have in mind, and we'll arrange a site visit.
Last reviewed 2026-07-19.