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 March?
In March, a glazed extension typically costs £2,950–£4,450 per m² of floor area, including VAT at 20% (standard rate). For a typical 18 m² project that is roughly £53,000–£80,000. That range is adjusted for the East of England, where domestic building work typically costs around 6% above the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (13 m²) | £38,500–£58,000 |
| Typical project (18 m²) | £53,000–£80,000 |
| Larger project (25 m²) | £74,000–£111,000 |
| Rate per m² | £2,950–£4,450 |
Your quote will depend mainly on:
- Lighting and finishes
- Cladding material
- Overheating and energy design
- Access for large glass panels
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a glazed extension in March?
Here is how the rules work for a glazed extension in 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.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
From survey to sign-off, the job normally involves:
- Structural design for steel frames and glass supports
- Building control sign-off
- Large-format sliding doors and fixed glazing
- Cladding or render finish
- Foundations, walls and insulated roof
- Energy and overheating calculations where needed
How long does it take?
Expect 12 to 16 weeks on site; glazing lead times can be 6 to 10 weeks. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
Building in March
Many towns in the East of England have estates built since the 1970s, where garage conversions and rear extensions are popular.
Projects in March (PE15) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 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 March
How long do large glass panels take to arrive?
Often 6 to 10 weeks after final measurements, so we order them as soon as the structure is built.
How much does a glazed extension cost in March?
In March, a glazed extension typically costs £2,950–£4,450 per m² of floor area, including VAT at 20% (standard rate). A typical 18 m² project comes to roughly £53,000–£80,000. Your fixed price depends on the survey and drawings.
Can large glass panels be lifted in?
Some need a crane or glass-lifting robot. We plan access during design.
Do you build glazed extensions in March?
Yes. We build glazed extensions across March, including postcodes PE15. Every project starts with a free home visit.
Does it need planning permission?
The same rules as other extensions apply, but contemporary designs in conservation areas are assessed carefully. We discuss the design approach with you before applying.