Carrickfergus, County Antrim
Single-storey rear extension in Carrickfergus
Ground-floor space across the back of the house, usually for a kitchen, dining or family room. If you live in Carrickfergus and want to know what a single-storey rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Carrickfergus sits in County Antrim, with postcode districts including BT38. A single-storey rear extension in Carrickfergus is mostly built from the garden side, so the house stays usable for most of the job.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a single-storey rear extension cost in Carrickfergus?
For Carrickfergus we work from the Northern Ireland rate: £1,650–£2,700 per square metre of new floor, including VAT, standard specification. 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 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission for a single-storey rear extension in Carrickfergus?
Planning for a single-storey rear extension in Carrickfergus follows the Northern Irish householder rules.
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 has no larger-extension prior approval route; anything beyond permitted development needs a planning application.
Conservation areas, Areas of Outstanding Natural Beauty and listed buildings restrict permitted development in Northern Ireland. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Carrickfergus like to extend?
Carrickfergus 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 a single-storey rear extension in Carrickfergus comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Paperwork handled
Planning or permitted development, building control approval, structural design and neighbour agreements are all handled by us.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Single-storey rear extensions near Carrickfergus
Close by, we work in Holywood, about 5.4 miles away, and Newtownabbey, about 5.6 miles away.
- Single-storey rear extension in Holywood
- Single-storey rear extension in Newtownabbey
- Single-storey rear extension in Bangor
- Single-storey rear extension in Dundonald
- Single-storey rear extension in Larne
Other work in Carrickfergus:
FAQ
Single-storey rear extension questions in Carrickfergus
Do I need a party wall agreement?
Northern Ireland has no Party Wall Act; we agree any shared-wall work with your neighbour in writing.
What postcode areas do you cover around Carrickfergus?
Including BT38, and the surrounding County Antrim area.
Is a flat roof or a pitched roof better?
A warm flat roof keeps the extension low under first-floor windows and suits a roof lantern; a pitched or lean-to roof gives a vaulted ceiling. Both last for decades when built properly.
Is the site visit in Carrickfergus free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
How much does a single-storey rear extension cost in Carrickfergus?
As a guide, £1,650–£2,700 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £20,000–£32,500 at that rate. Your written price follows the survey.
How long does a rear extension take to build in Carrickfergus?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.