Castlereagh, County Down
Semi-detached rear extension in Castlereagh
Single or two-storey extensions for semi-detached houses, with side access and one party wall. We design, get the approvals for and build rear extensions for semi-detached houses in Castlereagh and the surrounding area, with one contract from the first survey to building control sign-off.
We cover Castlereagh (BT8) as part of our County Down work. Where a Castlereagh semi already has a small lean-to at the back, we usually replace it rather than extend it.
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 semi-detached 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 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission for a semi-detached rear extension in Castlereagh?
Planning for a semi-detached rear extension in Castlereagh 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'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.
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. At the first visit we measure what is there now and tell you which route fits: permitted development or a planning application.
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 semi-detached rear extension in Castlereagh comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Approvals
Permitted development check or planning application, then building control drawings to the Northern Ireland Technical Booklets and structural calculations, plus a written agreement with neighbours for any shared-wall work.
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.
Semi-detached rear extensions near Castlereagh
Neighbouring places we cover include Belfast (2.3 miles) and Dundonald (3.7 miles).
- Semi-detached rear extension in Belfast
- Semi-detached rear extension in Dundonald
- Semi-detached rear extension in Holywood
- Semi-detached rear extension in Newtownabbey
- Semi-detached rear extension in Lisburn
Other work in Castlereagh:
FAQ
Semi-detached rear extension questions in Castlereagh
What postcode areas do you cover around Castlereagh?
Including BT8, and the surrounding County Down area.
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.
Can I match pebbledash or render?
Yes. Many semis are refinished with new render across the whole back elevation so old and new match.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
Is the site visit in Castlereagh free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
How much does a semi-detached 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.