Thornaby-on-Tees, North Yorkshire
Semi-detached rear extension in Thornaby-on-Tees
We plan and build rear extensions for semi-detached houses for homeowners in Thornaby-on-Tees. Single or two-storey extensions for semi-detached houses, with side access and one party wall. Start with a free site visit, then a written price once the design is agreed.
Thornaby-on-Tees is covered from our North Yorkshire round, including TS16, TS17 and TS18. Where a Thornaby-on-Tees semi already has a small lean-to at the back, we usually replace it rather than extend it.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Thornaby-on-Tees?
A semi-detached rear extension in Thornaby-on-Tees is priced at £1,710–£2,790 per square metre including VAT as a guide, before kitchen fit-out and fees. North East prices are among the lowest in our range; former mining ground is the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £20,500–£33,500 |
| 4 m wide × 5 m deep (20 m²) | £34,000–£56,000 |
| 4 m wide × 6 m deep (24 m²) | £41,000–£67,000 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission for a semi-detached rear extension in Thornaby-on-Tees?
Planning for a semi-detached rear extension in Thornaby-on-Tees follows the English householder rules.
English permitted development (Class A) allows a single-storey rear extension of 3 metres on a terraced or semi-detached house and 4 metres on a detached one, measured from the original house, with a maximum height of 4 metres and eaves of no more than 3 metres within 2 metres of a boundary.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
If 3 or 4 metres is not enough, England's prior approval route allows 6 metres on a terraced or semi-detached house and 8 metres on a detached house for a single-storey rear extension. Neighbours are consulted, the council decides within 42 days, and the fee is £249, rising to £310 from 8 December 2026.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Thornaby-on-Tees like to extend?
Terraces and semis are typical around Thornaby-on-Tees. On terraces a single-storey rear extension across the back yard is usually the practical choice; semis often have room for more.
How a semi-detached rear extension in Thornaby-on-Tees comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Paperwork handled
Planning, prior approval or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Semi-detached rear extensions near Thornaby-on-Tees
Neighbouring places we cover include Ingleby Barwick (1.0 miles) and Stockton-on-Tees (2.5 miles).
- Semi-detached rear extension in Ingleby Barwick
- Semi-detached rear extension in Stockton-on-Tees
- Semi-detached rear extension in Yarm
- Semi-detached rear extension in Billingham
- Semi-detached rear extension in Middlesbrough
Other work in Thornaby-on-Tees:
FAQ
Semi-detached rear extension questions in Thornaby-on-Tees
Can you match the brick or stone on my Thornaby-on-Tees house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Can I match pebbledash or render?
Yes. Many semis are refinished with new render across the whole back elevation so old and new match.
Who will build my extension?
Vetted building teams working under contract to us. Your contract is with S&K Property Investments and Improvement Ltd for the design and the build.
Do I need planning permission for a rear extension in Thornaby-on-Tees?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.