Antrim side extensions, designed and built
If you live in Antrim and want more space without moving, a side extension is one of the most practical ways to get it. We handle the drawings, approvals and the build.
- Guide price in AntrimFrom £18,500 inc VAT
- PlanningDepends on the NI limits; checked at the survey
- Build time10–18 weeks on site
- Postcode districtsBT41
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.
The planning position for a specific Antrim address depends on its history and any designations, which is why we check it at the first visit.
In Northern Ireland building control is run by the councils under the Building Regulations (Northern Ireland). We submit full plans or a building notice and book the inspections through to completion.
Applications are decided by your council, which handles local planning in Northern Ireland.
Side extension prices in Antrim
For Antrim we adjust our national guide rates by ×0.86, the factor we use for Northern Ireland. Figures include VAT; your written quote after the survey replaces them.
Typical rates in 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 |
Try the guide-price tool to see a range for your own size and finish.
Working in Antrim
Across BT41, we can visit, measure and advise. Neighbouring towns we cover include Ballymena (10 miles), Newtownabbey (13 miles), Belfast (14 miles), Lisburn (15 miles).
For homes towards County Londonderry, Magherafelt is around 17 miles away. In Northern Ireland, extension projects follow the NI planning rules and council building control, which we account for from the first survey.
Who a side extension suits
- Homes needing a utility, study or ground-floor bedroom
- Houses where the rear garden is small
- Detached and semi-detached houses with side land
Councils often prefer side extensions to sit slightly back from the front of the house with a lower roof, so the original building still reads clearly. We design to those principles from the start to avoid redesigns.
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 Antrim 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
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Side extension questions answered
Who do I contract with for a side extension in Antrim?
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 see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Antrim, 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 Antrim?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
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 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 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.