Cockfosters, Greater London
Glazed rear extension in Cockfosters
Full-height glass, slim frames and big rooflights for the most open rear room. If you live in Cockfosters 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.
We cover Cockfosters (EN4, N14 and N20) as part of our Greater London work. If your garden in Cockfosters 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 Cockfosters?
Guide prices for a glazed rear extension in Cockfosters start from our London rate of £3,640–£6,240 per square metre, including VAT. 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 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission for a glazed rear extension in Cockfosters?
Here is how the rules in England apply to a glazed rear extension in Cockfosters.
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 Cockfosters like to extend?
Cockfosters is mostly 1930s semis, short terraces and post-war houses, so full-width single-storey and two-storey rear extensions are realistic on many plots. Some later estates had permitted development rights removed by condition, so we check the planning history first. Glass-led rear extensions in Cockfosters are planned around which way the garden faces, because that decides the glass specification.
How a glazed rear extension in Cockfosters 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.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Paperwork handled
Planning, prior approval or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Glazed rear extensions near Cockfosters
From Cockfosters, the nearest places we also cover are East Barnet (0.6 miles) and New Barnet (1.2 miles).
- Glazed rear extension in East Barnet
- Glazed rear extension in New Barnet
- Glazed rear extension in Hadley Wood
- Glazed rear extension in Barnet
- Glazed rear extension in Totteridge
Other work in Cockfosters:
FAQ
Glazed rear extension questions in Cockfosters
Do I need planning permission for a rear extension in Cockfosters?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
How much does a glazed rear extension cost in Cockfosters?
As a guide, £3,640–£6,240 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £43,500–£75,000 at that rate. Your written price follows the survey.
Will a glass extension be too hot?
Not if it is designed for its orientation, with solar-control glass, shading and ventilation.
What postcode areas do you cover around Cockfosters?
Including EN4, N14 and N20, and the surrounding Greater London area.
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.
Can you match the brick or stone on my Cockfosters house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.