Flat roof extensions for homes in Northwich
If you live in Northwich and want more space without moving, a flat roof extension is one of the most practical ways to get it. We handle the drawings, approvals and the build.
- Guide price in NorthwichFrom £19,500 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time10–16 weeks on site
- Postcode districtsCW8, CW9
What should I budget for a flat roof extension in Northwich?
These guide figures apply our North West England adjustment (×0.95) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Northwich: £1,660 to £3,180 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £19,500 – £23,500 | £23,000 – £30,000 | £29,500 – £38,500 |
| 4 m × 5 m 20 m² | £33,000 – £39,000 | £38,500 – £49,500 | £49,000 – £64,000 |
| 5 m × 6 m 30 m² | £49,500 – £58,500 | £58,000 – £74,500 | £74,000 – £95,500 |
For a figure based on your own dimensions, use our guide-price tool.
Do I need planning permission in Northwich?
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 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.
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
- Warm-roof design with insulation above the deck
- Falls and outlets designed to drain properly
- Lanterns or rooflights with upstands
- Membrane choice: single-ply, EPDM or GRP
- Parapets or edge trims and flashings to the house
Height is often what decides a flat roof. Under first-floor windows, a pitched roof may not fit at all; a flat roof keeps the extension low while still giving a good ceiling height inside.
Working in Northwich
Across CW8, CW9, we can visit, measure and advise. We also work in nearby Winsford (5 miles), Warrington (10 miles), Runcorn (10 miles), Widnes (11 miles).
Altrincham, in Greater Manchester, is roughly 11 miles from Northwich and also on our list. The North West has a high share of Victorian and Edwardian terraces with rear yards and outriggers, plus large areas of inter-war semis in the suburbs.
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
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
The build is managed from start to finish, inspected at each stage and signed off on completion.
Your questions about a flat roof extension in Northwich
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Northwich, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
How long does a flat roof extension take to build in Northwich?
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 Northwich?
Yes. We cover Northwich and the surrounding parts of Cheshire. Site visits are free and there is no obligation.
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.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,660 to £3,180 per m² including VAT.
Book a free site visit in Northwich
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.