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 Letchworth Garden City?
In Letchworth Garden City, 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. Building costs in the East of England run about 6% above the UK average, and the figures for Letchworth Garden City are adjusted to reflect that. 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 |
The biggest cost drivers are:
- Steel framing
- Access for large glass panels
- Overheating and energy design
- Cladding material
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a glazed extension in Letchworth Garden City?
Whether you need planning permission depends on your house and its location 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
Handled as part of most glazed extensions:
- Cladding or render finish
- Energy and overheating calculations where needed
- Building control sign-off
- Structural design for steel frames and glass supports
- Electrics, heating and finishes
- Large-format sliding doors and fixed glazing
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 Letchworth Garden City
Many towns in the East of England have estates built since the 1970s, where garage conversions and rear extensions are popular.
From SG6 outwards, we take on projects throughout Letchworth Garden City and the surrounding parts of Hertfordshire.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and 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 Letchworth Garden City
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.
Can large glass panels be lifted in?
Some need a crane or glass-lifting robot. We plan access during design.
How much does a glazed extension cost in Letchworth Garden City?
In Letchworth Garden City, 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.
Who approves a glazed extension in Letchworth Garden City?
Planning matters in Letchworth Garden City go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
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.