Glass box extensions in Marlow: design, approvals and build
Thinking about a glass extension for your Marlow 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 price in MarlowFrom £33,500 inc VAT
- PlanningSame limits as single-storey rear; glazing checked for building regs
- Build time10–16 weeks on site
- Postcode districtsSL7
What should I budget for a glass extension in Marlow?
Labour and material costs vary across the UK, so for Marlow we use our South East England factor (×1.12). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Marlow: £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 |
For a figure based on your own dimensions, use our guide-price tool.
Covering Marlow
Our survey diary covers Marlow, including SL7. Nearby, we also take on projects in High Wycombe (4 miles), Gerrards Cross (9 miles), Amersham (10 miles), Chalfont St Peter (10 miles).
Maidenhead, in Berkshire, is roughly 4 miles from Marlow and also on our list. Homes across the South East range from Victorian terraces in the older town centres to large detached houses on the edges, so the right extension type varies street by street.
Included in a typical project
- Drainage details for frameless roofs
- Planning drawings that show the glass detail
- Design with specialist glazing input
- Steel or glass beams and slim-frame glazing
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.
Do I need planning permission in Marlow?
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.
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).
Our process, step by step
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
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
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.
Your questions about a glass extension in Marlow
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Marlow, 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 Marlow?
Yes. We cover Marlow and the surrounding parts of Buckinghamshire. Site visits are free and there is no obligation.
Will my neighbours in Marlow 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.
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 Marlow.
Book a free site visit in Marlow
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.