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 Sunbury-on-Thames?
In Sunbury-on-Thames, a glazed extension typically costs £3,150–£4,700 per m² of floor area, including VAT at 20% (standard rate). For a typical 18 m² project that is roughly £56,500–£84,500. Prices across the South East are typically 12% above the UK average for this kind of work, which is reflected in the range for Sunbury-on-Thames. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (13 m²) | £41,000–£61,000 |
| Typical project (18 m²) | £56,500–£84,500 |
| Larger project (25 m²) | £79,000–£117,500 |
| Rate per m² | £3,150–£4,700 |
The biggest cost drivers are:
- Steel framing
- Access for large glass panels
- Glazing size, specification and lead time
- 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 Sunbury-on-Thames?
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
The work we manage on a glazed extension:
- Building control sign-off
- Contemporary design and planning drawings
- Electrics, heating and finishes
- Cladding or render finish
- Foundations, walls and insulated roof
- Structural design for steel frames and glass supports
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 Sunbury-on-Thames
Commuter towns across the South East have many 1930s and post-war semis that suit rear extensions and hip-to-gable loft conversions.
If your home is in Sunbury-on-Thames or close by in Walton-on-Thames, Ashford and Weybridge, a free home visit is the first step.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 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 Sunbury-on-Thames
Is triple glazing necessary?
Not always. High-performance double glazing can meet the standards; triple glazing helps in exposed locations.
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.
How much does a glazed extension cost in Sunbury-on-Thames?
In Sunbury-on-Thames, a glazed extension typically costs £3,150–£4,700 per m² of floor area, including VAT at 20% (standard rate). A typical 18 m² project comes to roughly £56,500–£84,500. Your fixed price depends on the survey and drawings.
How long does a glazed extension take in Sunbury-on-Thames?
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.
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.