Bedroom extensions across Friern Barnet
Planning a bedroom extension in Friern Barnet? We survey the house, work out the planning route, draw the design and build it, so you deal with one team from the first visit to the completion certificate.
- Guide price in Friern BarnetFrom £33,500 inc VAT
- PlanningUsually a householder application
- Build time14–22 weeks on site
- Postcode districtsN2, N3, N10, N11, N12
Do I need planning permission in Friern Barnet?
In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
How much does a bedroom extension cost in Friern Barnet?
For Friern Barnet we adjust our national guide rates by ×1.3, the factor we use for London. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Friern Barnet: £2,080 to £4,160 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| One bedroom 12 m² | £33,500 – £41,500 | £33,500 – £44,000 | £37,000 – £50,000 |
| Bedroom and en-suite 18 m² | £37,000 – £46,000 | £44,000 – £57,500 | £56,000 – £75,000 |
| Two rooms 30 m² | £62,000 – £76,500 | £74,000 – £96,000 | £93,500 – £125,000 |
Try the guide-price tool to see a range for your own size and finish.
Working in Friern Barnet
Our survey diary covers Friern Barnet, including N2, N3, N10, N11, N12, N20. Nearby, we also take on projects in Muswell Hill (2 miles), Finchley (2 miles), Wood Green (2 miles), Palmers Green (2 miles).
For homes towards Hertfordshire, Potters Bar is around 6 miles away. Across London, terraced houses with narrow side returns and tight access are the norm, which shapes everything from party wall notices to how materials reach the back garden.
When a bedroom extension makes sense
- Homeowners who want an en-suite master bedroom
- Growing families
- Multi-generational households
What happens next
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Your questions about a bedroom extension in Friern Barnet
Who do I contract with for a bedroom extension in Friern Barnet?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Do I need building regulations approval in Friern Barnet?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
How long does a bedroom extension take to build in Friern Barnet?
On site, typically 14 to 22 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
How much does a bedroom extension cost?
Our guide range is about £2,080 to £4,160 per m² including VAT. A bedroom with an en-suite of about 18 m² is typically £44,000 to £57,500 at standard spec, depending on whether it is part of a larger two-storey build.
Can I add a ground-floor bedroom for a relative?
Yes. A ground-floor bedroom with an accessible shower room is a common request. If it will be lived in as a self-contained home, planning treats it differently, so tell us how it will be used.
Book a free site visit in Friern Barnet
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.