Two-storey extensions for detached houses in Carryduff
Adding a two-storey extension for a detached house in Carryduff gives you two new rooms stacked on one footprint. Here's how we'd approach it, what it typically costs and the rules that apply in Northern Ireland.
Carryduff: the key facts for this kind of project.
- Postcode districts
- BT8
- County / area
- County Down, Northern Ireland
- Price region
- Northern Ireland
- Guide price
- £76,000–£101,500 (£1,800–£2,420 per m²)
- Approval route
- Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); most others need planning permission.
- Nearest towns
- Castlereagh (3.8 miles), Belfast (5.7 miles), Lisburn (6 miles)
- Distance to Bangor (County Down)
- about 13.2 miles
- First visit
- Free, no obligation
About a two-storey extension for a detached house
A two-storey extension for a detached house is a two-floor addition to the side, rear or both of a house that stands on its own plot. Detached houses often have room on more than one side, so there is more choice of layout and fewer shared-wall issues. The design still needs to respect boundaries, neighbours' windows and the look of the house.
Around Carryduff we also work in Castlereagh, Belfast and Lisburn, and across the rest of County Down. Postcode district in and near Carryduff: BT8.
What it costs in Carryduff
Expect a two-storey extension for a detached house in Carryduff to land somewhere around £76,000–£101,500 for a 3 m × 7 m footprint on two floors (42 m² of new floor space). Our Northern Ireland guide rate is £1,800–£2,420 per m², including VAT. The fastest way to a firmer number is a free site visit, after which we price the design stage in writing.
| Spec | Per m² | A 3 m × 7 m footprint on two floors (42 m² of new floor space) |
|---|---|---|
| Essential | £1,660–£2,230 per m² | £69,500–£93,500 |
| Standard | £1,800–£2,420 per m² | £76,000–£101,500 |
| Premium | £2,160–£2,900 per m² | £91,000–£122,000 |
Planning and building control in Carryduff
In Northern Ireland, a two-storey rear extension on a detached house can be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary, with height, materials and roof pitch conditions. Side and wraparound designs normally need a planning application, which costs £347 per dwelling.
Approval in Northern Ireland: Planning application for works to a house: £347. Councils aim to decide local applications within an average of 15 weeks; many take longer.
Building control: Building control approval from the local council under the Building Regulations (Northern Ireland), using the Technical Booklets.
Design points for Carryduff homes
Larger spans and steelwork
Bigger extensions often mean wider openings and longer spans, which need more steel and sometimes a steel frame. The engineer designs these early, because the size of the steel affects ceiling heights, floor depths and the cost.
Choosing the best side
On a detached house you can often extend on either side or the rear. We look at orientation for daylight, where the stairs and landing are, the distance to each boundary, drains and trees, so the extension goes where it adds the most useful space.
How we'd run your project
Visit and first ideas
One of our team visits your house in Carryduff, checks the walls, roof and drains, and sketches out options with you.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.
Questions about two-storey extensions for detached houses in Carryduff
Which postcodes do you cover around Carryduff?
We cover Carryduff (BT8) and nearby places including Castlereagh, Belfast and Lisburn, plus the rest of County Down. The first site visit is free.
How long does a two-storey extension for a detached house take?
Allow 4 to 8 weeks for survey and design, then the approval period (councils aim to decide local applications within an average of 15 weeks; many take longer), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.
Do I need planning permission for a two-storey extension for a detached house in Carryduff?
Carryduff is in Northern Ireland. Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); most others need planning permission.
Can I extend a detached house on both sides?
Sometimes. With planning permission, a council may accept extensions on both sides if the house stays well proportioned and keeps gaps to the boundaries. It is more common to extend on one side and the rear, or with a wraparound. We look at the plot as a whole before suggesting more than one extension.
Is a detached house extension a better investment than moving?
It often costs less than the gap between your house and a larger one nearby, once property tax, legal fees and removal costs are counted, but that depends on your area. Extending also has limits: every street has a ceiling price. We give you build costs so you can compare them with local asking prices.
Nearby
Close to Carryduff? We work across the area, including:
Other extensions in Carryduff
- Rear
- Side
- Wraparound
- Part two-storey
- Over a garage
- First floor
- Semi-detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Carryduff · Two-storey extensions for detached houses across County Down
Book a free site visit in Carryduff and we'll tell you what's possible, what approvals you need and what the design stage would cost.