Extensions in County Antrim: design, planning and build
Looking to extend your home in County Antrim? Start here: extension types, guide prices for County Antrim, the planning rules that apply and how a project runs.
- Towns listed8
- Price regionNorthern Ireland (×0.86)
- Planning rulesNorthern Ireland
- Postcode districts31
Towns we cover in County Antrim
Towns we cover here include Belfast, Lisburn, Newtownabbey, Castlereagh.
What extensions cost in County Antrim
Every figure below is a guide for County Antrim, adjusted for Northern Ireland build costs (×0.86) and including VAT. Design and council fees are shown separately on each page.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Single-storey rear extensions | 20 m² | £35,000 – £45,000 |
| Wraparound extensions | 25 m² | £49,000 – £62,500 |
| Double-storey extensions | 32 m² | £49,500 – £65,000 |
| Kitchen extensions | 20 m² | £36,000 – £46,000 |
| Orangery extensions | 16 m² | £38,500 – £48,500 |
| Side return extensions | 11 m² | £22,500 – £28,500 |
Which extension suits a County Antrim home?
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.
Start by comparing single-storey rear extensions, bungalow extensions and annexe extensions: between them they cover most of the layouts we see requested for houses like these.
Planning rules 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.
In a conservation area or area of townscape character the permitted development rights are more limited, listed homes need listed building consent, and if rights have been removed by a condition, any extension needs an application.
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.
Choose an extension type
- Home office extensions · from £13,500
- Conservatory replacement extensions · from £17,000
- Building regulations for extensions · from £750
- Flat roof extensions · from £18,000
- Extensions over a garage · from £20,500
- Utility and boot room extensions · from £12,000
- Bungalow extensions · from £22,500
- Double-storey extensions · from £32,500
- Glass box extensions · from £25,500
- Pitched roof extensions · from £19,000
- Side return extensions · from £15,000
- Planning permission for extensions · from £300
- Wraparound extensions · from £30,500
- Side extensions · from £18,500
- Orangery extensions · from £25,500
- Annexe extensions · from £47,000
- Bedroom extensions · from £22,000
- Timber frame extensions · from £18,000
- Extension plans and drawings · from £1,000
- Single-storey rear extensions · from £18,000
- Kitchen extensions · from £23,000
- Porch extensions · from £3,400
Neighbouring areas
Questions about extensions in County Antrim
How much does an extension cost in County Antrim?
With our Northern Ireland factor (×0.86), a standard-spec 20 m² single-storey extension is a guide £35,000 to £45,000 including VAT. Prices for every type are linked on this page.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Will my neighbours need to be told?
If you apply for planning permission the council notifies neighbours, and we agree access with them in writing for work near a shared boundary.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for County Antrim, and the guide-price tool gives a range for your own size and finish in about a minute.
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.