What is a glazed extension?
A glazed or contemporary extension uses large panes of glass, slim aluminium frames and modern cladding to create a bright room that contrasts with the original house. Frameless corners, structural glass roofs and minimal sliding doors are typical features.
How much does a glazed extension cost in Grantham?
In Grantham, a glazed extension typically costs £2,650–£4,000 per m² of floor area, including VAT at 20% (standard rate). For a typical 18 m² project that is roughly £47,500–£72,000. That range is adjusted for the East Midlands, where domestic building work typically costs around 5% below the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (13 m²) | £34,500–£52,000 |
| Typical project (18 m²) | £47,500–£72,000 |
| Larger project (25 m²) | £66,000–£100,000 |
| Rate per m² | £2,650–£4,000 |
The biggest cost drivers are:
- Overheating and energy design
- Access for large glass panels
- Cladding material
- Lighting and finishes
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a glazed extension in Grantham?
Approvals for a glazed extension in Grantham follow the rules for England. In England a single-storey rear extension is often permitted development: broadly up to 3 metres deep on a semi-detached or terraced house and 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres within 2 metres of a boundary, and covering no more than half the garden. The larger home extension scheme allows up to 6 or 8 metres if you notify the council first and neighbours have a chance to comment. In conservation areas, National Parks and National Landscapes the larger home extension route, side extensions and cladding are not permitted development. Flats and houses whose rights have been removed need a planning application, and listed buildings need listed building consent.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
We check this for your address before design work starts, so there are no surprises later.
What we handle
From survey to sign-off, the job normally involves:
- Energy and overheating calculations where needed
- Structural design for steel frames and glass supports
- Foundations, walls and insulated roof
- Contemporary design and planning drawings
- Electrics, heating and finishes
- Cladding or render finish
How long does it take?
Build time is typically 12 to 16 weeks on site; glazing lead times can be 6 to 10 weeks. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Grantham
In the East Midlands, many estates built since the 1960s have integral garages that convert well into a study or bedroom.
Our Grantham coverage includes postcode districts NG31, and we also work in nearby places such as Newark on Trent, Melton Mowbray and Oakham.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about glazed extensions in Grantham
Can large glass panels be lifted in?
Some need a crane or glass-lifting robot. We plan access during design.
How long does a glazed extension take in Grantham?
Typically 12 to 16 weeks on site; glazing lead times can be 6 to 10 weeks. Design and approvals beforehand usually take 3 to 4 months.
How much does a glazed extension cost in Grantham?
In Grantham, a glazed extension typically costs £2,650–£4,000 per m² of floor area, including VAT at 20% (standard rate). A typical 18 m² project comes to roughly £47,500–£72,000. Your fixed price depends on the survey and drawings.
Will a glass extension be too hot in summer?
It can be if poorly designed. Solar-control glass, roof overhangs and opening vents reduce overheating, and building regulations may require calculations to show the design works.
Is VAT charged?
Yes, VAT at the standard 20% rate applies to extensions. Our guide prices include it.