Extensions over a garage in Belfast: design, approvals and build
We design and build over-garage extensions for houses in Belfast, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in BelfastFrom £20,500 inc VAT
- PlanningPermission from the council needed
- Build time12–18 weeks on site
- Postcode districtsBT1, BT2, BT6, BT7, BT12
How much does an over-garage extension cost in Belfast?
Prices below are for Belfast, using the Northern Ireland factor of ×0.86. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Belfast: £1,550 to £2,920 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £20,500 – £25,500 | £21,500 – £28,000 | £27,500 – £35,500 |
| Over a large single garage 16 m² | £24,500 – £30,500 | £28,500 – £37,500 | £37,000 – £47,000 |
| Over a double garage 24 m² | £37,000 – £45,500 | £43,000 – £56,000 | £55,500 – £70,500 |
Try the guide-price tool to see a range for your own size and finish.
Will the council need to approve it?
In Northern Ireland the Planning (General Permitted Development) Order 2015 lets some single-storey rear extensions go ahead without planning permission, up to 3 m on a semi-detached or terraced house and 4 m on a detached house, within height and boundary limits. Larger, side and two-storey extensions normally need planning permission from the council, and building control approval is separate.
Homes in conservation areas, areas of townscape character and listed buildings have tighter rules, so we always check the property's status and planning history before design starts.
Northern Ireland has no Party Wall Act. Where work is on or close to a shared boundary, we agree access and protection with your neighbour in writing before work starts.
Applications are decided by your council, which handles local planning in Northern Ireland.
Working in Belfast
Postcode districts we cover around Belfast include BT1, BT2, BT6, BT7, BT12, BT13. The same team covers Castlereagh (2 miles), Newtownabbey (4 miles), Lisburn (7 miles), Carrickfergus (10 miles), all within easy reach.
For homes towards County Down, Newtownards is around 9 miles away. In Northern Ireland, extension projects follow the NI planning rules and council building control, which we account for from the first survey.
Is an over-garage extension right for your house?
- 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
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
We visit your Belfast home, measure up, talk through what you want and check the planning position.
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.
Your questions about an over-garage extension in Belfast
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Belfast, 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 over-garage extension take to build in Belfast?
On site, typically 12 to 18 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Do I need building regulations approval in Belfast?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
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.
How much does a room over a garage cost?
Our guide range is about £1,550 to £2,920 per m² including VAT. A single-garage room of about 12 m² usually costs £21,500 to £28,000 at standard spec, more if the garage needs rebuilding.
Book a free site visit in Belfast
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.