Extensions over a garage for homes in County Londonderry
If you live in County Londonderry and want more space without moving, an over-garage extension is one of the most practical ways to get it. We handle the drawings, approvals and the build.
- Guide priceFrom £20,500 inc VAT
- PlanningPermission from the council needed
- Towns covered4
- Site visitFree, no obligation
Towns in County Londonderry
What is included
- Design and householder planning application
- Opening into the existing first floor
- New floor structure, walls and roof
- Insulation, electrics, heating and finish
- Structural survey of garage walls and foundations
Covering County Londonderry
Towns we cover in County Londonderry include Derry/Londonderry, Coleraine, Limavady, Magherafelt. Northern Ireland's housing ranges from city terraces to large numbers of detached houses and bungalows on rural plots, many in render, where single-storey extensions fit easily.
Planning and approvals in County Londonderry
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.
The planning position for a specific County Londonderry address depends on its history and any designations, which is why we check it at the first visit.
Building close to a public sewer needs the agreement of NI Water, which we check during design.
Applications are decided by your council, which handles local planning in Northern Ireland.
Guide prices for County Londonderry
These guide figures apply our Northern Ireland adjustment (×0.86) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in County Londonderry: £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 |
Want a range for your exact size? The guide-price tool takes about a minute.
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
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Questions people ask about over-garage extensions
Will my neighbours in County Londonderry be involved?
If a planning application is needed, the council notifies neighbours. Where work is close to a shared boundary, we agree access and protection with them in writing.
How long does an over-garage extension take to build in County Londonderry?
On site, typically 12 to 18 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for County Londonderry, 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 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.
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 County Londonderry
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.