Castlereagh, County Down
Single-storey rear extension in Castlereagh
Thinking about a single-storey rear extension in Castlereagh? Ground-floor space across the back of the house, usually for a kitchen, dining or family room. Our team handles the drawings, the planning route and the build, and your contract is with one company throughout.
We cover Castlereagh (BT8) as part of our County Down work. On terraces, semis and detached bungalows like those around Castlereagh, a single-storey rear extension is usually the simplest way to fix a small back kitchen without touching the bedrooms.
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 Castlereagh?
For Castlereagh 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 Castlereagh?
Here is how the rules in Northern Ireland apply to a single-storey rear extension in Castlereagh.
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 Castlereagh like to extend?
Castlereagh 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 Castlereagh 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.
Design and guide price
Two or three layout options with a guide price for each, so you choose the design knowing what it costs.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for council building control.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Single-storey rear extensions near Castlereagh
From Castlereagh, the nearest places we also cover are Belfast (2.3 miles) and Dundonald (3.7 miles).
- Single-storey rear extension in Belfast
- Single-storey rear extension in Dundonald
- Single-storey rear extension in Holywood
- Single-storey rear extension in Newtownabbey
- Single-storey rear extension in Lisburn
Other work in Castlereagh:
FAQ
Single-storey rear extension questions in Castlereagh
Do I need planning permission for a rear extension in Castlereagh?
Often not for a single-storey rear extension of up to 3 metres (4 metres detached) under Northern Ireland's permitted development rules, outside conservation areas.
Do you handle building control in Castlereagh?
Yes. We apply to the council's building control team and hand over the completion certificate.
Will the extension make the room behind it dark?
Not if it is designed well. Rooflights or a lantern over the old back room, and a wide opening into it, keep daylight reaching the middle of the house.
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.
Can you match the brick or stone on my Castlereagh house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
How much does a single-storey rear extension cost in Castlereagh?
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.