Extra bedroom and en-suite extensions in Carryduff
For an extra bedroom and en-suite extension in Carryduff, the first questions are always the same: how big, which approvals, and what it will cost. This page answers all three for County Down.
Before you start in Carryduff, here's what applies.
- Postcode districts
- BT8
- County / area
- County Down, Northern Ireland
- Price region
- Northern Ireland
- Guide price
- £49,500–£66,500 (£1,760–£2,380 per m²), plus £5,500–£11,000 for the en-suite
- Approval route
- It may be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary.
- 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 an extra bedroom and en-suite extension
This service suits you if you need another bedroom, or want a main bedroom with its own bathroom, without converting the loft or moving. You get a first-floor layout that connects well to your landing, an en-suite designed for plumbing and ventilation, a useful room downstairs, the approvals your nation needs and the build, managed by us and carried out by vetted teams working under S&K.
Carryduff sits about 13.2 miles from Bangor (County Down). Closer to home, Castlereagh is 3.8 miles away and Belfast 5.7 miles.
What it costs in Carryduff
A guide price for Carryduff: around £49,500–£66,500 (plus £5,500–£11,000 for the en-suite) for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). That works out at £1,760–£2,380 per m² of new floor space, including VAT at 20%. Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.
| Spec | Per m² | A 4 m × 3.5 m footprint on two floors (28 m² of new floor space) |
|---|---|---|
| Essential | £1,620–£2,190 per m² | £45,500–£61,000 |
| Standard | £1,760–£2,380 per m² | £49,500–£66,500 |
| Premium | £2,110–£2,850 per m² | £59,000–£80,000 |
Planning and building control in Carryduff
In Northern Ireland, a rear extra bedroom extension can be permitted development within 3 m of the original rear wall and 7 m from the rear boundary. Upper side windows within 15 m of a neighbouring boundary must be obscure-glazed and non-opening. Other designs need a planning application costing £347, plus building control approval.
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
Escape window and fire safety
A new first-floor bedroom needs an escape window with a clear opening of at least 0.33 m², at least 450 mm wide and high, and the bottom no more than 1,100 mm above the floor, unless there is a protected route to the stairs. We design the windows to meet this.
Sound and privacy
Bedrooms above a kitchen or family room benefit from an insulated floor to reduce noise. Side-facing upstairs windows usually have to be obscure-glazed, so we place the main bedroom window to the rear and the en-suite window to the side where possible.
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.
Drawings, then consent
We draw the scheme, check it against the rules in Northern Ireland, and take it through the right consent with the council.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.
Questions about extra bedroom and en-suite extensions in Carryduff
How much does an extra bedroom and en-suite extension cost in Carryduff?
Our guide for Northern Ireland, which covers Carryduff, is £1,760–£2,380 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £49,500–£66,500 (plus £5,500–£11,000 for the en-suite). Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Who handles building control for a project in Carryduff?
We handle it as part of the project. What's needed in Northern Ireland: building control approval from the local council under the Building Regulations (Northern Ireland), using the Technical Booklets. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.
How long does an extra bedroom and en-suite extension 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.
What goes on the ground floor below a new bedroom?
Whatever suits you: a bigger kitchen, a family room, a study, a utility or a downstairs shower room. The ground floor usually costs about the same whatever it is used for, apart from kitchen units and bathroom fittings, which are priced separately.
Does an extra bedroom add value to my house?
It usually does, though not always by the full cost. Nationwide's 2025 research found that adding a double bedroom to a two-bed house was linked to about 13% higher value, and a double bedroom and bathroom on a three-bed, one-bathroom house up to 24%. Local ceiling prices still apply.
Nearby
Nearby towns we cover for extra bedroom and en-suite extensions:
Other extensions in Carryduff
All two-storey extension services in Carryduff · Extra bedroom and en-suite extensions 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.