Brighton annexe extensions, designed and built
Brighton homeowners can use us for the whole annexe extension project: survey, design, planning or permitted development checks, building regulations and the build itself.
- Guide price in BrightonFrom £61,500 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsBN1, BN2, BN3, BN41
Covering Brighton
Site visits are available across Brighton (BN1, BN2, BN3, BN41). Neighbouring towns we cover include Hove (1 mile), Portslade (3 miles), Peacehaven (6 miles), Seaford (11 miles).
Shoreham-by-Sea, in West Sussex, is roughly 6 miles from Brighton and also on our list. 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.
What should I budget for an annexe extension in Brighton?
Labour and material costs vary across the UK, so for Brighton we use our South East England factor (×1.12). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Brighton: £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 |
Try the guide-price tool to see a range for your own size and finish.
Included in a typical project
- Separate or shared heating and hot water
- Planning application describing ancillary use
- Fire separation and alarms to building regulations
- Design for accessibility: level thresholds, wider doors, walk-in shower
- Kitchenette, shower room and bedroom finish
Will the council need to approve it?
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 Brighton address depends on its history and any designations, which is why we check it at the first visit.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
How the project works
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
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
The build is managed from start to finish, inspected at each stage and signed off on completion.
Common questions in Brighton
Who do I contract with for an annexe extension in Brighton?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Will my neighbours in Brighton be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Do I need building regulations approval in Brighton?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
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.
How much does an annexe extension cost?
Our guide range is about £2,240 to £4,260 per m² including VAT. A one-bedroom annexe of about 35 m² is typically £94,000 to £118,000 at standard spec in Brighton.
Book a free site visit in Brighton
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.