Barnet, Greater London
Two-storey rear extension in Barnet
For homes in Barnet, a two-storey rear extension is often the simplest way to gain space without moving. A larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. We take it from survey to completion certificate.
Barnet is covered from our Greater London round, including EN4, EN5, N3 and N12. Two-storey rear extensions suit semi-detached houses in Barnet best, where the extra bedroom matters as much as the bigger kitchen.
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 two-storey rear extension cost in Barnet?
In Barnet, our guide for a two-storey rear extension is £2,340–£3,510 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 × 5 m footprint, two floors (30 m²) | £70,000–£105,500 |
| 4 m × 6 m footprint, two floors (48 m²) | £112,500–£168,500 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission for a two-storey rear extension in Barnet?
Here is how the rules in England apply to a two-storey rear extension in Barnet.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
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 Barnet like to extend?
Barnet 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. In Greater London we check the neighbours' rear windows first, because the upper floor is where most two-storey schemes win or lose planning.
How a two-storey rear extension in 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.
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.
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.
Two-storey rear extensions near Barnet
Neighbouring places we cover include New Barnet (1.1 miles) and Totteridge (1.2 miles).
- Two-storey rear extension in New Barnet
- Two-storey rear extension in Totteridge
- Two-storey rear extension in East Barnet
- Two-storey rear extension in Hadley Wood
- Two-storey rear extension in Cockfosters
Other work in Barnet:
FAQ
Two-storey rear extension questions in Barnet
What postcode areas do you cover around Barnet?
Including EN4, EN5, N3, N12, N20 and NW7, and the surrounding Greater London area.
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.
Is two-storey cheaper per square metre than single-storey?
Usually yes, because the foundations and roof are shared across twice the floor area. The total cost is higher.
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 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.
Do I need planning permission for a rear extension in Barnet?
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.