Thornaby-on-Tees annexe extensions, designed and built
Thornaby-on-Tees homeowners can use us for the whole annexe extension project: survey, design, planning or permitted development checks, building regulations and the build itself.
- Guide price in Thornaby-on-TeesFrom £50,000 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsTS17
Do I need planning permission in Thornaby-on-Tees?
In England an annexe that stays part of the household and connects to the house is assessed as an extension, but its size usually takes it beyond permitted development, so a householder application describing the ancillary use is the normal route.
The planning position for a specific Thornaby-on-Tees address depends on its history and any designations, which is why we check it at the first visit.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
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).
Local to Thornaby-on-Tees
Site visits are available across Thornaby-on-Tees (TS17). The same team covers Stockton-on-Tees (3 miles), Yarm (3 miles), Billingham (4 miles), Darlington (10 miles), all within easy reach.
Just over the North Yorkshire border, Middlesbrough is about 4 miles away. Across the North East, houses often have rear yards or modest gardens, so compact, well-lit single-storey extensions make the biggest difference.
What should I budget for an annexe extension in Thornaby-on-Tees?
Labour and material costs vary across the UK, so for Thornaby-on-Tees we use our North East England factor (×0.91). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Thornaby-on-Tees: £1,820 to £3,460 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £50,000 – £63,000 | £54,500 – £68,500 | £68,000 – £86,500 |
| One-bedroom annexe 35 m² | £63,500 – £80,000 | £76,000 – £96,000 | £95,500 – £121,500 |
| Larger annexe 45 m² | £81,500 – £102,500 | £98,000 – £123,000 | £122,500 – £156,000 |
Try the guide-price tool to see a range for your own size and finish.
When an annexe extension makes sense
- Multi-generational families
- Homes with a large side or rear garden
- Relatives who need support close by
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Your questions about an annexe extension in Thornaby-on-Tees
Do you cover all of Thornaby-on-Tees?
Yes. We cover Thornaby-on-Tees and the surrounding parts of County Durham. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Thornaby-on-Tees, 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 an annexe extension take to build in Thornaby-on-Tees?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 10–16 weeks design and approvals.
How much does an annexe extension cost?
Our guide range is about £1,820 to £3,460 per m² including VAT. A one-bedroom annexe of about 35 m² is typically £76,000 to £96,000 at standard spec in Thornaby-on-Tees.
Does an annexe extension need planning permission?
Usually yes, because of its size and the way it will be used. Councils check that it stays ancillary to the main house, so the application must describe the use clearly.
Book a free site visit in Thornaby-on-Tees
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.