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 Thatcham?
In Thatcham, 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. We start from a UK-wide guide and adjust it for the South East, where labour and materials are typically about 12% above average. 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 |
Your quote will depend mainly on:
- Lighting and finishes
- Glazing size, specification and lead time
- Cladding material
- Overheating and energy design
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 Thatcham?
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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
What we take care of:
- Structural design for steel frames and glass supports
- Electrics, heating and finishes
- Contemporary design and planning drawings
- Energy and overheating calculations where needed
- Large-format sliding doors and fixed glazing
- Foundations, walls and insulated roof
How long does it take?
Expect 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 Thatcham
The South East has a broad mix of housing, from Victorian terraces in the towns to post-war semis and newer estates, so extension types vary street by street.
Thatcham sits in Berkshire, about 13 miles west of Reading. We cover the whole of Thatcham, including postcodes RG18.
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 in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about glazed extensions in Thatcham
How long does a glazed extension take in Thatcham?
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.
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.
Is VAT charged?
Yes, VAT at the standard 20% rate applies to extensions. Our guide prices include it.
How much does a glazed extension cost in Thatcham?
In Thatcham, 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.
