Side extensions in County Antrim
We design and build side extensions for houses in County Antrim, with a written price once the survey and design are done and one point of contact throughout.
- Guide priceFrom £18,500 inc VAT
- PlanningDepends on the NI limits; checked at the survey
- Towns covered8
- Site visitFree, no obligation
Towns in County Antrim
Local to County Antrim
Towns we cover in County Antrim include Belfast, Lisburn, Newtownabbey, Castlereagh, Carrickfergus, Ballymena, Antrim, Larne. 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.
Side extension prices in County Antrim
Prices below are for County Antrim, using the Northern Ireland factor of ×0.86. They are guide ranges including VAT for the build only, not a quote.
Typical rates in County Antrim: £1,500 to £2,920 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 5 m 12 m² | £18,500 – £23,000 | £21,000 – £27,500 | £26,500 – £35,500 |
| 3 m × 6 m 18 m² | £27,000 – £33,000 | £31,500 – £41,500 | £40,000 – £53,000 |
| 3 m × 8 m 24 m² | £36,000 – £43,500 | £42,000 – £55,000 | £53,500 – £70,500 |
For a figure based on your own dimensions, use our guide-price tool.
Planning and approvals in County Antrim
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.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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.
Is a side extension right for your house?
- Homes needing a utility, study or ground-floor bedroom
- Detached and semi-detached houses with side land
- Houses where the rear garden is small
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
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.
Your questions about a side extension in County Antrim
How long does a side extension take to build in County Antrim?
On site, typically 10 to 18 weeks once approvals are in place. Before that, allow 6–14 weeks design and approvals.
Do you cover all of County Antrim?
Yes, across the whole of County Antrim. Site visits are free and there is no obligation.
Will my neighbours in County Antrim 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 much does a side extension cost?
Our guide range is about £1,500 to £2,920 per m² including VAT, depending on specification, so a standard 18 m² single-storey side extension lands around £31,500 to £41,500 in County Antrim.
Can I build over my driveway?
Yes, if the foundations work and you keep any parking the council requires. Drains and services under drives are common, so we check before design.
Book a free site visit in County Antrim
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.