Double-storey extensions in County Durham
A double-storey extension in County Durham starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide priceFrom £34,500 inc VAT
- PlanningUsually a householder application
- Towns covered14
- Site visitFree, no obligation
Towns in County Durham
Extensions in and around County Durham
Towns we cover in County Durham include Darlington, Hartlepool, Stockton-on-Tees, Durham, Chester-le-Street, Billingham, Stanley, Consett. Across the North East, houses often have rear yards or modest gardens, so compact, well-lit single-storey extensions make the biggest difference.
Will the council need to approve it?
In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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).
Who a double-storey extension suits
- Homeowners who would otherwise consider moving
- Houses with enough distance to the rear or side boundary
- Growing families who need a bedroom as well as a bigger kitchen
What should I budget for a double-storey extension in County Durham?
For County Durham we adjust our national guide rates by ×0.91, the factor we use for North East England. Figures include VAT; your written quote after the survey replaces them.
Typical rates in County Durham: £1,410 to £2,730 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m, two floors 24 m² | £34,500 – £41,500 | £39,000 – £51,500 | £50,000 – £66,000 |
| 4 m × 4 m, two floors 32 m² | £45,000 – £54,000 | £52,000 – £68,500 | £66,500 – £87,500 |
| 4 m × 6 m, two floors 48 m² | £67,500 – £81,000 | £78,500 – £103,000 | £100,000 – £131,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
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
We visit your County Durham home, measure up, talk through what you want and check the planning position.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
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.
Questions people ask about double-storey extensions
Do you cover all of County Durham?
Yes, across the whole of County Durham. Site visits are free and there is no obligation.
Do I need building regulations approval in County Durham?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for County Durham, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Is a two-storey extension cheaper per square metre?
Usually. Our guide range is about £1,410 to £2,730 per m² of new floor area including VAT, compared with £1,590 to £3,090 per m² for single-storey work, because the foundations and roof are shared across two floors.
Does a double-storey extension need planning permission?
Often, yes. In England a two-storey rear extension can be permitted development only if it projects no more than 3 m and sits at least 7 m from the rear boundary, with matching roof pitch and obscure side windows. Side extensions over one storey always need planning permission. We confirm the route at the survey.
Book a free site visit in County Durham
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.