Barnet, Greater London
Kitchen-diner rear extension in Barnet
An open-plan kitchen, dining and family room that opens straight onto the garden. If you live in Barnet and want to know what a kitchen-diner rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Barnet and its postcode districts EN4, EN5, N3 and N12 are part of our Greater London coverage. For Barnet kitchens we plan the extraction route and the island drainage before the slab is poured, so nothing has to be chased in later.
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 kitchen-diner rear extension cost in Barnet?
For Barnet we work from the London rate: £2,470–£4,030 per square metre of new floor, including VAT, 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) | £29,500–£48,500 |
| 4 m wide × 5 m deep (20 m²) | £49,500–£80,500 |
| 4 m wide × 6 m deep (24 m²) | £59,500–£96,500 |
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 kitchen-diner rear extension in Barnet?
Planning for a kitchen-diner rear extension in Barnet follows the English householder rules.
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.
If 3 or 4 metres is not enough, England's prior approval route allows 6 metres on a terraced or semi-detached house and 8 metres on a detached house for a single-storey rear extension. Neighbours are consulted, the council decides within 42 days, and the fee is £249, rising to £310 from 8 December 2026.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. At the first visit we measure what is there now and tell you which route fits: permitted development, prior approval or a planning application.
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.
How a kitchen-diner rear extension in Barnet 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.
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.
Kitchen-diner rear extensions near Barnet
We also build kitchen-diner rear extensions in nearby New Barnet (1.1 miles) and Totteridge (1.2 miles).
- Kitchen-diner rear extension in New Barnet
- Kitchen-diner rear extension in Totteridge
- Kitchen-diner rear extension in East Barnet
- Kitchen-diner rear extension in Hadley Wood
- Kitchen-diner rear extension in Cockfosters
Other work in Barnet:
FAQ
Kitchen-diner 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.
Is the site visit in Barnet free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Do you fit the kitchen?
Yes, whether you buy it yourself or we supply it. We take the measurements from the built shell, not the drawings.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
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.
Can you match the brick or stone on my Barnet house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.