Cockfosters, Greater London
Kitchen-diner rear extension in Cockfosters
For homes in Cockfosters, a kitchen-diner rear extension is often the simplest way to gain space without moving. An open-plan kitchen, dining and family room that opens straight onto the garden. We take it from survey to completion certificate.
We cover Cockfosters (EN4, N14 and N20) as part of our Greater London work. We usually keep the working kitchen where the old one was and put the dining table in the new space by the doors, which suits most Cockfosters homes.
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 Cockfosters?
Guide prices for a kitchen-diner rear extension in Cockfosters start from our London rate of £2,470–£4,030 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) | £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 |
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 kitchen-diner rear extension in Cockfosters?
Here is how the rules in England apply to a kitchen-diner rear extension in Cockfosters.
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.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
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?
Much of Cockfosters 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 kitchen-diner rear extension in Cockfosters 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.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
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 Cockfosters
Neighbouring places we cover include East Barnet (0.6 miles) and New Barnet (1.2 miles).
- Kitchen-diner rear extension in East Barnet
- Kitchen-diner rear extension in New Barnet
- Kitchen-diner rear extension in Hadley Wood
- Kitchen-diner rear extension in Barnet
- Kitchen-diner rear extension in Totteridge
Other work in Cockfosters:
FAQ
Kitchen-diner rear extension questions in Cockfosters
What postcode areas do you cover around Cockfosters?
Including EN4, N14 and N20, and the surrounding Greater London area.
How long does a rear extension take to build in Cockfosters?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
How big should a kitchen-diner be?
Around 25 to 35 m² for the combined kitchen, dining and seating areas suits most family homes. Your survey shows what fits the house.
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.
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.
Is the site visit in Cockfosters free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.