Extensions over a garage in Bath: design, approvals and build
We design and build over-garage extensions for houses in Bath, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in BathFrom £24,000 inc VAT
- PlanningHouseholder application needed
- Build time12–18 weeks on site
- Postcode districtsBA1, BA2
Covering Bath
Site visits are available across Bath (BA1, BA2). We also work in nearby Keynsham (6 miles), Frome (10 miles), Nailsea (18 miles), Portishead (19 miles).
Trowbridge, in Wiltshire, is roughly 8 miles from Bath and also on our list. In the South West, local stone, render and brick vary from town to town, so matching materials is a big part of designing an extension that looks right.
How much does an over-garage extension cost in Bath?
Prices below are for Bath, using the South West England factor of ×1.02. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Bath: £1,840 to £3,470 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £24,000 – £30,000 | £25,500 – £33,500 | £33,000 – £42,000 |
| Over a large single garage 16 m² | £29,000 – £36,000 | £34,000 – £44,500 | £44,000 – £55,500 |
| Over a double garage 24 m² | £44,000 – £54,000 | £51,000 – £66,500 | £66,000 – £83,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Who an over-garage extension suits
- Homes where the landing can connect to the new room
- Detached and link-detached houses with an attached garage
- Families needing a bedroom without losing garden
Planning rules that apply in Bath
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.
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.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
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.
Over-garage extension questions answered
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Bath, 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 Bath?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Who do I contract with for an over-garage extension in Bath?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
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.
Can my garage take the weight of a room on top?
Some can and some cannot. Many garages have a single-skin wall or shallow foundations. Our structural engineer checks this before we give a fixed price.
Book a free site visit in Bath
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.