County Antrim
Permitted development rear extensions in County Antrim
Designing to the no-application limits, with a certificate of lawfulness of proposed use or development as proof. Rear extensions in County Antrim: we cover 7 towns including Belfast, Lisburn and Newtownabbey, with design, approvals and the build under one contract.

County Antrim has terraces near the centre, semis on the edges and many detached houses and bungalows in the surrounding countryside, where plots are often generous.
How much does a permitted development rear extension cost in County Antrim?
A permitted development rear extension in County Antrim is priced at £1,650–£2,700 per square metre including VAT as a guide, before kitchen fit-out and fees. Northern Ireland prices are the lowest in our range.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £20,000–£32,500 |
| 4 m wide × 5 m deep (20 m²) | £33,000–£54,000 |
| 4 m wide × 6 m deep (24 m²) | £39,500–£64,500 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission in County Antrim?
Northern Ireland's permitted development rules allow a single-storey rear extension of 3 metres on terraced and semi-detached houses and 4 metres on detached houses, with a 4 metre height limit. Listed buildings, conservation areas and houses with removed rights need planning permission from the council.
Northern Ireland's 2015 Order allows a two-storey rear extension of up to 3 metres where at least 7 metres is left to the rear boundary. Anything larger, or in a conservation area, needs a planning application to the council.
Conservation areas, Areas of Outstanding Natural Beauty and listed buildings restrict permitted development in Northern Ireland.
Where in County Antrim do we work?
FAQ
Questions people ask
Is permitted development the same as planning permission?
No; it is a national grant of permission for work within set limits, so no application is needed.
Do I still need Building Regulations?
Yes, always.
How long does a certificate of lawfulness of proposed use or development take?
Councils should decide within 8 weeks.
Do you cover all of County Antrim?
We cover 7 towns and districts in County Antrim, including Belfast, Lisburn and Newtownabbey.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.