Dartford, Kent
Single-storey rear extension in Dartford
Ground-floor space across the back of the house, usually for a kitchen, dining or family room. If you live in Dartford and want to know what a single-storey rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
We cover Dartford (DA1) as part of our Kent work. A single-storey rear extension in Dartford is mostly built from the garden side, so the house stays usable for most of the job.
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 single-storey rear extension cost in Dartford?
Guide prices for a single-storey rear extension in Dartford start from our South East England rate of £2,130–£3,470 per square metre, including VAT. South East prices run above our West Midlands baseline, mainly on labour rates and clay-soil foundations.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £25,500–£41,500 |
| 4 m wide × 5 m deep (20 m²) | £42,500–£69,500 |
| 4 m wide × 6 m deep (24 m²) | £51,000–£83,500 |
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 single-storey rear extension in Dartford?
Here is how the rules in England apply to a single-storey rear extension in Dartford.
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 Dartford like to extend?
Commuter semis and detached houses make up much of Dartford, and longer gardens make England's prior approval route for deeper rear extensions worth considering.
How a single-storey rear extension in Dartford 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.
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.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Single-storey rear extensions near Dartford
We also build single-storey rear extensions in nearby Bexley (2.8 miles) and Swanley (3.8 miles).
- Single-storey rear extension in Bexley
- Single-storey rear extension in Swanley
- Single-storey rear extension in Belvedere
- Single-storey rear extension in Swanscombe
- Single-storey rear extension in Chafford Hundred
Other work in Dartford:
FAQ
Single-storey rear extension questions in Dartford
Is the site visit in Dartford free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Do you handle building control in Dartford?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Do I need a structural engineer?
Yes for the beam over the new opening and usually for the foundations. Their calculations go to building control with the drawings.
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.
How much does a single-storey rear extension cost in Dartford?
As a guide, £2,130–£3,470 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £25,500–£41,500 at that rate. Your written price follows the 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.