Chalk Farm, Greater London
Semi-detached rear extension in Chalk Farm
Single or two-storey extensions for semi-detached houses, with side access and one party wall. We design, get the approvals for and build rear extensions for semi-detached houses in Chalk Farm and the surrounding area, with one contract from the first survey to building control sign-off.
Chalk Farm sits in Greater London, with postcode districts including NW1, NW3 and NW5. In Chalk Farm we measure the attached neighbour's extension at the survey, because it often sets the sensible depth for yours.
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 semi-detached rear extension cost in Chalk Farm?
In Chalk Farm, our guide for a semi-detached rear extension is £2,470–£4,030 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 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 semi-detached rear extension in Chalk Farm?
Here is how the rules in England apply to a semi-detached rear extension in Chalk Farm.
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.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
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. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Chalk Farm like to extend?
Period terraces in Chalk Farm sit alongside flats, and the difference matters: houses usually keep permitted development rights, while flats and maisonettes need planning permission for any rear extension.
How a semi-detached rear extension in Chalk Farm comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Semi-detached rear extensions near Chalk Farm
From Chalk Farm, the nearest places we also cover are Camden Town (0.3 miles) and Belsize Park (1.0 miles).
- Semi-detached rear extension in Camden Town
- Semi-detached rear extension in Belsize Park
- Semi-detached rear extension in Holloway
- Semi-detached rear extension in Barnsbury
- Semi-detached rear extension in Highgate
Other work in Chalk Farm:
FAQ
Semi-detached rear extension questions in Chalk Farm
Do you handle building control in Chalk Farm?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
How much does a semi-detached rear extension cost in Chalk Farm?
As a guide, £2,470–£4,030 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £29,500–£48,500 at that rate. Your written price follows the survey.
How long does a semi extension take?
10 to 16 weeks on site for a single-storey extension.
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.
Is the site visit in Chalk Farm free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Can you match the brick or stone on my Chalk Farm house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.