Lisburn side extensions, designed and built
From the first sketch to final sign-off, we plan and build side extensions in Lisburn and the surrounding County Antrim area.
- Guide price in LisburnFrom £18,500 inc VAT
- PlanningDepends on the NI limits; checked at the survey
- Build time10–18 weeks on site
- Postcode districtsBT10, BT11, BT17, BT27, BT28
Extensions in and around Lisburn
Our survey diary covers Lisburn, including BT10, BT11, BT17, BT27, BT28. Nearby, we also take on projects in Belfast (7 miles), Castlereagh (7 miles), Newtownabbey (11 miles), Antrim (15 miles).
For homes towards County Down, Newtownards is around 15 miles away. 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.
How much does a side extension cost in Lisburn?
Prices below are for Lisburn, using the Northern Ireland factor of ×0.86. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Lisburn: £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.
What we take care of
- Structure, roof tied into the house
- Windows, doors and finishes to match
- Planning route checked or application made
- Foundations near boundaries and any drains
- Survey, design and street-view drawings
- New openings through the side wall
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.
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.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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.
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.
How the project works
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
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
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 Lisburn
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Lisburn, 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 you cover all of Lisburn?
Yes. We cover Lisburn and the surrounding parts of County Antrim. Site visits are free and there is no obligation.
How long does a side extension take to build in Lisburn?
On site, typically 10 to 18 weeks once approvals are in place. Before that, allow 6–14 weeks design and approvals.
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.
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 Lisburn.
Book a free site visit in Lisburn
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.