Part single, part two-storey extensions in Durham

Quick reference for homeowners in Durham.

Postcode districts: DH1
County / area: County Durham, England
Price region: North East England
Guide price: £65,000–£89,000 (£1,800–£2,480 per m²)
Approval route: It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission.
Nearest towns: Brandon (2.5 miles), Spennymoor (5.5 miles), Chester-le-Street (5.7 miles)
Distance to Darlington: about 17.5 miles
First visit: Free, no obligation

About a part single, part two-storey extension

A part single, part two-storey extension suits you if you want a generous ground floor but only need one extra room upstairs, or if a full two-storey design would affect a neighbour too much. You get design options that test where the two-storey part works best, the approvals your nation needs, structural design, building regulations approval and the build, carried out by vetted teams working under S&K.

Around Durham we also work in Brandon, Spennymoor and Chester-le-Street, and across the rest of County Durham. Postcode district in and near Durham: DH1.

What it costs in Durham

In North East England, which includes Durham, we'd expect a part single, part two-storey extension to cost around £65,000–£89,000 for a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total), or £1,800–£2,480 per m² including VAT. Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total)
Essential	£1,660–£2,280 per m²	£59,500–£82,000
Standard	£1,800–£2,480 per m²	£65,000–£89,000
Premium	£2,160–£2,970 per m²	£78,000–£107,000

Planning and building regulations in Durham

In England, the extension can only be permitted development if it goes no more than 3 m beyond the original rear wall and stays at least 7 m from the rear boundary, with matching materials and roof pitch. We check the whole design against the rules, including the 50% garden coverage limit. If any part fails, or extends beyond a side wall on two floors, you need planning permission, costing £548 (or £575 for applications made from 8 December 2026).

Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

Design points for Durham homes

Where to put the two-storey part

The two-storey section usually works best away from the closest neighbour, with the single-storey part on that boundary side. We test a few positions against neighbours' windows, the upstairs layout and the roof shape before choosing the one to take forward.

Structure at the step

The first-floor wall above often sits over the new open-plan space, so it needs a steel beam or frame to carry it. Loads come down at different points than in a full two-storey design, and the engineer sizes the foundations to suit each part.

How we'd run your project

Free site visit
We visit your home in Durham, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Get it approved
Once you're happy with the design we submit it to the council for Durham and deal with any questions from the planning officer.
Engineer it
Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.
Build and hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.

Questions about part single, part two-storey extensions in Durham

Who handles building regulations for a project in Durham?

We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

How much does a part single, part two-storey extension cost in Durham?

Our guide for North East England, which covers Durham, is £1,800–£2,480 per m² including VAT. A typical project with a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) comes to about £65,000–£89,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Which postcodes do you cover around Durham?

We cover Durham (DH1) and nearby places including Brandon, Spennymoor and Chester-le-Street, plus the rest of County Durham. The first site visit is free.

Can I add roof lights to the single-storey part?

Yes. Roof lights or a lantern over the single-storey part are one of the main reasons to choose this design, as they light the middle of a deep kitchen. In England they count towards the Part L glazing allowance, normally 25% of the new floor area plus windows removed, so we balance them with the rear doors.

Can the single-storey part be deeper than the two-storey part?

With planning permission, yes, and that is often the point of the design: the ground floor projects further into the garden while the first floor stays back from neighbours. Under permitted development, the depth limits for extensions of more than one storey can apply to the whole extension, so we confirm which route applies before drawings are finalised.

Nearby

Other towns near Durham:

Other extensions in Durham

All two-storey extension services in Durham · Part single, part two-storey extensions across County Durham

The quickest next step is a visit. We'll look at your house in Durham and give you an honest view of the options.