Flat roof extensions in Dartford
We design and build flat roof extensions for houses in Dartford, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in DartfordFrom £23,500 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time10–16 weeks on site
- Postcode districtsDA1, DA2, DA9
Local to Dartford
Our survey diary covers Dartford, including DA1, DA2, DA9. The same team covers Swanley (4 miles), Gravesend (7 miles), Strood (12 miles), Sevenoaks (12 miles), all within easy reach.
Just over the Greater London border, Bexley is about 3 miles away. The South East has a broad mix of 1930s semis, post-war estates, newer developments and period cottages, and many houses have enough garden for a generous rear extension.
Do I need planning permission in Dartford?
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
What is included
- Lanterns or rooflights with upstands
- Falls and outlets designed to drain properly
- Warm-roof design with insulation above the deck
- Membrane choice: single-ply, EPDM or GRP
- Parapets or edge trims and flashings to the house
Flat roof extension prices in Dartford
For Dartford we adjust our national guide rates by ×1.12, the factor we use for South East England. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Dartford: £1,960 to £3,750 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £23,500 – £28,000 | £27,500 – £35,000 | £34,500 – £45,500 |
| 4 m × 5 m 20 m² | £39,000 – £46,000 | £45,500 – £58,500 | £58,000 – £75,500 |
| 5 m × 6 m 30 m² | £58,500 – £69,000 | £68,500 – £87,500 | £87,000 – £113,000 |
For a figure based on your own dimensions, use our guide-price tool.
How the project works
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
We visit your Dartford home, measure up, talk through what you want and check the planning position.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Flat roof extension questions answered
Who do I contract with for a flat roof extension in Dartford?
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.
How long does a flat roof extension take to build in Dartford?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 4–12 weeks design and approvals.
Do you cover all of Dartford?
Yes. We cover Dartford and the surrounding parts of Kent. Site visits are free and there is no obligation.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,960 to £3,750 per m² including VAT.
Can I walk on a flat roof extension?
Only for maintenance unless it is designed as a terrace. A roof terrace or balcony needs planning permission and a different structure.
Book a free site visit in Dartford
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.