Annexe extensions for homes in West Sussex
Thinking about an annexe extension for your West Sussex home? Start with a free site visit: we measure up, check what the council will allow and give you honest guide figures on the day.
- Guide priceFrom £61,500 inc VAT
- PlanningUsually a householder application
- Towns covered12
- Site visitFree, no obligation
Towns in West Sussex
Covering West Sussex
Towns we cover in West Sussex include Crawley, Worthing, Bognor Regis, Littlehampton, Horsham, Haywards Heath, Chichester, Burgess Hill. The South East has a broad mix of 1930s semis, post-war estates, newer developments and period cottages, and many houses have enough garden for a generous rear extension.
Included in a typical project
- Kitchenette, shower room and bedroom finish
- Design for accessibility: level thresholds, wider doors, walk-in shower
- Separate or shared heating and hot water
- Fire separation and alarms to building regulations
Guide prices for West Sussex
Labour and material costs vary across the UK, so for West Sussex we use our South East England factor (×1.12). The ranges include VAT and exclude design, structural and council fees.
Typical rates in West Sussex: £2,240 to £4,260 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £61,500 – £77,500 | £67,000 – £84,500 | £84,000 – £106,500 |
| One-bedroom annexe 35 m² | £78,000 – £98,500 | £94,000 – £118,000 | £117,500 – £149,000 |
| Larger annexe 45 m² | £100,500 – £126,500 | £120,500 – £151,500 | £151,000 – £192,000 |
For a figure based on your own dimensions, use our guide-price tool.
Planning and approvals in West Sussex
In England an annexe that stays part of the household and connects to the house is assessed as an extension, but its size usually takes it beyond permitted development, so a householder application describing the ancillary use is the normal route.
The planning position for a specific West Sussex address depends on its history and any designations, which is why we check it at the first visit.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
What happens next
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
We visit your West Sussex home, measure up, talk through what you want and check the planning position.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Your questions about an annexe extension in West Sussex
Do I need building regulations approval in West Sussex?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for West Sussex, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do you cover all of West Sussex?
Yes, across the whole of West Sussex. Site visits are free and there is no obligation.
Can the annexe have its own front door?
Yes, many do, but it should still connect to the main house to stay clearly part of it.
Does an annexe extension need planning permission?
Usually yes, because of its size and the way it will be used. Councils check that it stays ancillary to the main house, so the application must describe the use clearly.
Book a free site visit in West Sussex
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.