Part single, part two-storey extensions in Stockton-on-Tees

Useful details for planning a part single, part two-storey extension in Stockton-on-Tees.

Postcode districts: TS18, TS19 and TS21
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: Billingham (1.8 miles), Thornaby-on-Tees (2.5 miles), Middlesbrough (3.4 miles)
Distance to Darlington: about 9.8 miles
First visit: Free, no obligation

About a part single, part two-storey extension

A part single, part two-storey extension is an extension where the ground floor is wider or deeper than the floor above, so only part of it rises to two storeys. It usually gives a large kitchen or living area with roof lights below and one bedroom or bathroom above. It is often a good way to add space while limiting the effect on neighbours.

Around Stockton-on-Tees we also work in Billingham, Thornaby-on-Tees and Middlesbrough, and across the rest of County Durham. Postcode districts in and near Stockton-on-Tees: TS18, TS19 and TS21.

What it costs in Stockton-on-Tees

In North East England, which includes Stockton-on-Tees, 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 Stockton-on-Tees

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 Stockton-on-Tees 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.

Light into the kitchen

The single-storey part is the place for roof lights or a lantern, which bring daylight deep into the plan. In England, glazing is normally limited to 25% of the new floor area plus any windows removed, unless calculations show the house still performs, so we plan the balance early.

How we'd run your project

Look at the house
We start in Stockton-on-Tees with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Drawings, then consent
We draw the scheme, check it against the rules in England, and take it through the right consent with the council.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.

Questions about part single, part two-storey extensions in Stockton-on-Tees

Who handles building regulations for a project in Stockton-on-Tees?

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 Stockton-on-Tees?

Our guide for North East England, which covers Stockton-on-Tees, 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 Stockton-on-Tees?

We cover Stockton-on-Tees (TS18, TS19 and TS21) and nearby places including Billingham, Thornaby-on-Tees and Middlesbrough, plus the rest of County Durham. The first site visit is free.

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.

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.

Nearby

Close to Stockton-on-Tees? We work across the area, including:

Other extensions in Stockton-on-Tees

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

Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Stockton-on-Tees.