Brentwood, Essex
Glazed rear extension in Brentwood
Thinking about a glazed rear extension in Brentwood? Full-height glass, slim frames and big rooflights for the most open rear room. Our team handles the drawings, the planning route and the build, and your contract is with one company throughout.
Brentwood sits in Essex, with postcode districts including CM13, CM14 and CM15. Glass-led rear extensions in Brentwood are planned around which way the garden faces, because that decides the glass specification.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a glazed rear extension cost in Brentwood?
For Brentwood we work from the East of England rate: £2,970–£5,090 per square metre of new floor, including VAT, standard specification. East of England prices run slightly above our West Midlands baseline; clay soils near trees are the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £35,500–£61,000 |
| 4 m wide × 6 m deep (24 m²) | £71,000–£122,000 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a glazed rear extension in Brentwood?
The planning route for a glazed rear extension in Brentwood is set by England's householder rules and your council.
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.
New fabric must meet Approved Document L (2021 edition incorporating 2023 amendments): walls 0.18, roof 0.15 and floor 0.18 W/m²K, windows 1.4 W/m²K or Band B. Under the simple route, new windows, doors and rooflights should not exceed 25% of the extension floor area plus any openings removed; more glass is possible with a whole-house calculation.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Brentwood like to extend?
Post-war semis and newer estates are typical of Brentwood, and many have room for a full-width extension. Shrinkable clay is common in the East of England, so foundations near trees and hedges are designed to NHBC-style depth guidance.
How a glazed rear extension in Brentwood comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Design and guide price
Two or three layout options with a guide price for each, so you choose the design knowing what it costs.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Glazed rear extensions near Brentwood
Neighbouring places we cover include Harold Wood (3.6 miles) and Emerson Park (4.5 miles).
- Glazed rear extension in Harold Wood
- Glazed rear extension in Emerson Park
- Glazed rear extension in Billericay
- Glazed rear extension in Upminster
- Glazed rear extension in Hornchurch
Other work in Brentwood:
FAQ
Glazed rear extension questions in Brentwood
How much does a glazed rear extension cost in Brentwood?
As a guide, £2,970–£5,090 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £35,500–£61,000 at that rate. Your written price follows the survey.
Is the site visit in Brentwood free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Sliding or bifold doors?
Sliders give bigger panes and slimmer sightlines; bifolds open the whole width. Our guide compares them.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
How long does a rear extension take to build in Brentwood?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.