New Barnet, Greater London
Glazed rear extension in New Barnet
Full-height glass, slim frames and big rooflights for the most open rear room. If you live in New Barnet and want to know what a glazed rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
New Barnet sits in Greater London, with postcode districts including EN4, EN5 and N20. If your garden in New Barnet faces south, expect us to talk about overhangs and solar-control glass before frame colours.
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 New Barnet?
In New Barnet, our guide for a glazed rear extension is £3,640–£6,240 per square metre including VAT for a standard specification. London prices sit at the top of our range because of labour rates, access through the house, parking suspensions and skip licences.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £43,500–£75,000 |
| 4 m wide × 6 m deep (24 m²) | £87,500–£150,000 |
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 New Barnet?
The planning route for a glazed rear extension in New Barnet is set by England's householder rules and your council.
English permitted development (Class A) allows a single-storey rear extension of 3 metres on a terraced or semi-detached house and 4 metres on a detached one, measured from the original house, with a maximum height of 4 metres and eaves of no more than 3 metres 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. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in New Barnet like to extend?
Much of New Barnet is 1920s and 1930s semis and short terraces with longer gardens than inner London, which suit full-width single-storey rear extensions. Parking suspensions, skip licences and controlled hours on residential streets shape the programme more than the build itself.
How a glazed rear extension in New Barnet comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Glazed rear extensions near New Barnet
We also build glazed and glass-box rear extensions in nearby East Barnet (0.6 miles) and Barnet (1.1 miles).
- Glazed rear extension in East Barnet
- Glazed rear extension in Barnet
- Glazed rear extension in Cockfosters
- Glazed rear extension in Hadley Wood
- Glazed rear extension in Totteridge
Other work in New Barnet:
FAQ
Glazed rear extension questions in New Barnet
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.
Is the site visit in New Barnet free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Is a glass box a conservatory?
No. It is built to Building Regulations as part of the house, with insulated floor and roof, so it is usable all year.
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.
Do you handle building control in New Barnet?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
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.