Extensions over a garage across Thornaby-on-Tees
Our design and build teams take on over-garage extensions in Thornaby-on-Tees, from the first measured survey through planning and building control to the finished room.
- Guide price in Thornaby-on-TeesFrom £21,500 inc VAT
- PlanningHouseholder application needed
- Build time12–18 weeks on site
- Postcode districtsTS17
Working in Thornaby-on-Tees
We cover Thornaby-on-Tees and the postcode districts TS17. Neighbouring towns we cover include Stockton-on-Tees (3 miles), Yarm (3 miles), Billingham (4 miles), Darlington (10 miles).
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 over-garage extension in Thornaby-on-Tees?
These guide figures apply our North East England adjustment (×0.91) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Thornaby-on-Tees: £1,640 to £3,090 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £21,500 – £27,000 | £22,500 – £29,500 | £29,000 – £37,500 |
| Over a large single garage 16 m² | £26,000 – £32,500 | £30,500 – £39,500 | £39,000 – £50,000 |
| Over a double garage 24 m² | £39,000 – £48,500 | £45,500 – £59,000 | £58,500 – £74,500 |
For a figure based on your own dimensions, use our guide-price tool.
Will the council need to approve it?
In England any side extension over one storey, including a room built over a side garage, needs a householder planning application. The fee is £548 from 1 April 2026 and councils aim to decide within 8 weeks.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
Who an over-garage extension suits
- Detached and link-detached houses with an attached garage
- Families needing a bedroom without losing garden
- Homes where the landing can connect to the new room
Fitting the new room to the existing landing is the planning puzzle inside the house. We design the connection first, then the roof, so the extension does not end up with awkward steps or a corridor through a bedroom.
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
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
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Your questions about an over-garage extension in Thornaby-on-Tees
How long does an over-garage extension take to build in Thornaby-on-Tees?
On site, typically 12 to 18 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Will my neighbours in Thornaby-on-Tees be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
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 keep using the garage during the build?
Usually not for parking. The garage roof is removed and the space below is used for access and props for part of the build.
Does building over a garage need planning permission?
In England and the rest of the UK, adding a storey over a side garage almost always needs a planning application, because two-storey side extensions are outside permitted development.
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.