Glass box extensions across West Sussex
Thinking about a glass 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 £33,500 inc VAT
- PlanningSame limits as single-storey rear; glazing checked for building regs
- Towns covered12
- Site visitFree, no obligation
Towns in West Sussex
Glass extension prices in West Sussex
Prices below are for West Sussex, using the South East England factor of ×1.12. They are guide ranges including VAT for the build only, not a quote.
Typical rates in West Sussex: £3,360 to £6,500 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2 m × 4 m 8 m² | £33,500 – £40,500 | £33,500 – £42,500 | £38,500 – £52,000 |
| 3 m × 4 m 12 m² | £40,000 – £48,500 | £47,000 – £59,500 | £57,500 – £78,000 |
| 3 m × 6 m 18 m² | £60,000 – £73,000 | £70,500 – £89,000 | £86,500 – £117,000 |
Try the guide-price tool to see a range for your own size and finish.
Planning rules that apply in West Sussex
In England a glazed or orangery-style extension follows the same size limits as any single-storey rear extension: 3 m or 4 m without an application, or up to 6 m and 8 m through prior approval. Building regulations limit glazing to about a quarter of the new floor area plus the openings it replaces, unless whole-house calculations show the design still performs.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
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).
Local to West Sussex
Towns we cover in West Sussex include Crawley, Worthing, Bognor Regis, Littlehampton, Horsham, Haywards Heath, Chichester, Burgess Hill. In the South East, plenty of houses have already been extended once, which makes checking the remaining permitted development allowance an important early step.
What is included
- Drainage details for frameless roofs
- Design with specialist glazing input
- Whole-house energy calculations where needed
- Steel or glass beams and slim-frame glazing
- Planning drawings that show the glass detail
Solar gain is the risk. We specify solar-control glass, plan for opening vents or sliding panels, and avoid fully glazed roofs on south-facing extensions unless shading is included.
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
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
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
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Your questions about a glass 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.
How long does a glass extension take to build in West Sussex?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Will my neighbours in West Sussex 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.
How much does a glass extension cost?
Our guide range is about £3,360 to £6,500 per m² including VAT, because structural glass is made to order. A 12 m² standard-spec glass extension is typically £47,000 to £59,500 in West Sussex.
Are glass extensions cold in winter?
Modern double or triple glazing with warm-edge spacers and underfloor heating keeps them comfortable. They are not as warm as a solid room, and we explain the trade-off honestly.
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.