Annexe extensions in Yarm: design, approvals and build
Planning an annexe extension in Yarm? We survey the house, work out the planning route, draw the design and build it, so you deal with one team from the first visit to the completion certificate.
- Guide price in YarmFrom £50,000 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsTS15, TS16

Guide prices for Yarm
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 Yarm: £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 |
Want a range for your exact size? The guide-price tool takes about a minute.
Planning rules that apply in Yarm
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.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
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).
What we take care of
- Separate or shared heating and hot water
- Kitchenette, shower room and bedroom finish
- Fire separation and alarms to building regulations
- Design for accessibility: level thresholds, wider doors, walk-in shower
- Planning application describing ancillary use
Working in Yarm
Site visits are available across Yarm (TS15, TS16). Neighbouring towns we cover include Thornaby-on-Tees (3 miles), Stockton-on-Tees (5 miles), Billingham (6 miles), Darlington (8 miles).
Just over the North Yorkshire border, Middlesbrough is about 7 miles away. The North East has many brick terraces, colliery-era housing and post-war semis, with rear extensions and kitchen extensions the most common requests.
What happens next
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
We visit your Yarm home, measure up, talk through what you want and check the planning position.
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
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.
Common questions in Yarm
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Yarm, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do I need building regulations approval in Yarm?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Do you cover all of Yarm?
Yes. We cover Yarm and the surrounding parts of County Durham. Site visits are free and there is no obligation.
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.
Can the annexe have its own front door?
Yes, many do, but it should still connect to the main house to stay clearly part of it.
Book a free site visit in Yarm
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.