Glass box extensions in Penzance
Planning a glass extension in Penzance? We survey the house, work out the planning route, draw the design and build it, so you deal with one team from the first visit to the completion certificate.
- Guide price in PenzanceFrom £30,500 inc VAT
- PlanningSame limits as single-storey rear; glazing checked for building regs
- Build time10–16 weeks on site
- Postcode districtsTR18
Local to Penzance
We cover Penzance and the postcode districts TR18. Nearby, we also take on projects in Camborne (12 miles), Redruth (16 miles), Falmouth (21 miles), Truro (24 miles).
For homes towards Devon, Plymouth is around 64 miles away. South West homes range from terraced streets in the cities to stone cottages and bungalows in the countryside, and conservation areas are common in historic centres.
Planning rules that apply in Penzance
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).
Who a glass extension suits
- Period and listed-style houses where a light touch is wanted
- Garden-facing dining rooms
- Small infill spaces and side returns
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.
Glass extension prices in Penzance
Labour and material costs vary across the UK, so for Penzance we use our South West England factor (×1.02). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Penzance: £3,060 to £5,920 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2 m × 4 m 8 m² | £30,500 – £37,000 | £30,500 – £38,500 | £35,000 – £47,500 |
| 3 m × 4 m 12 m² | £36,500 – £44,500 | £42,500 – £54,000 | £52,500 – £71,000 |
| 3 m × 6 m 18 m² | £55,000 – £66,500 | £64,000 – £81,000 | £78,500 – £106,500 |
For a figure based on your own dimensions, use our guide-price tool.
From first visit to completion
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 Penzance home, measure up, talk through what you want and check the planning position.
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
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Common questions in Penzance
Do you cover all of Penzance?
Yes. We cover Penzance and the surrounding parts of Cornwall. Site visits are free and there is no obligation.
How long does a glass extension take to build in Penzance?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Do I need building regulations approval in Penzance?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
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.
How much does a glass extension cost?
Our guide range is about £3,060 to £5,920 per m² including VAT, because structural glass is made to order. A 12 m² standard-spec glass extension is typically £42,500 to £54,000 in Penzance.
Book a free site visit in Penzance
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.