Flat roof extensions in Finchley
Planning a flat roof extension in Finchley? 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 FinchleyFrom £27,000 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time10–16 weeks on site
- Postcode districtsN2, N3, N12, NW4, NW7
Covering Finchley
Our survey diary covers Finchley, including N2, N3, N12, NW4, NW7, NW11. The same team covers Golders Green (2 miles), Friern Barnet (2 miles), Muswell Hill (2 miles), Cricklewood (3 miles), all within easy reach.
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.
What should I budget for a flat roof extension in Finchley?
For Finchley 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 Finchley: £2,280 to £4,360 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £27,000 – £32,000 | £31,500 – £41,000 | £40,500 – £52,500 |
| 4 m × 5 m 20 m² | £45,500 – £53,500 | £53,000 – £68,000 | £67,500 – £87,500 |
| 5 m × 6 m 30 m² | £68,000 – £80,000 | £79,500 – £101,500 | £101,000 – £131,000 |
Try the guide-price tool to see a range for your own size and finish.
Included in a typical project
- Lanterns or rooflights with upstands
- Warm-roof design with insulation above the deck
- Falls and outlets designed to drain properly
- Membrane choice: single-ply, EPDM or GRP
- Parapets or edge trims and flashings to the house
Will the council need to approve it?
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.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
Our process, step by step
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
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
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
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Your questions about a flat roof extension in Finchley
Do I need building regulations approval in Finchley?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Who do I contract with for a flat roof extension in Finchley?
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.
Will my neighbours in Finchley be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £2,280 to £4,360 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 Finchley
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.