Glass box extensions across Henley-on-Thames
A glass extension in Henley-on-Thames starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in Henley-on-ThamesFrom £33,500 inc VAT
- PlanningSame limits as single-storey rear; glazing checked for building regs
- Build time10–16 weeks on site
- Postcode districtsRG9
Extensions in and around Henley-on-Thames
Site visits are available across Henley-on-Thames (RG9). We also work in nearby Thame (14 miles), Didcot (14 miles), Abingdon (18 miles), Oxford (20 miles).
Just over the Berkshire border, Reading is about 6 miles away. 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.
When a glass extension makes sense
- Small infill spaces and side returns
- Garden-facing dining rooms
- Period and listed-style houses where a light touch is wanted
Glass extension prices in Henley-on-Thames
For Henley-on-Thames we adjust our national guide rates by ×1.12, the factor we use for South East England. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Henley-on-Thames: £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 |
Want a range for your exact size? The guide-price tool takes about a minute.
Will the council need to approve it?
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 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.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Glass extension questions answered
How long does a glass extension take to build in Henley-on-Thames?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Henley-on-Thames, 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 I need building regulations approval in Henley-on-Thames?
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 £3,360 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 Henley-on-Thames.
Book a free site visit in Henley-on-Thames
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.