Double-storey extensions in County Down

Covering County Down

Our double-storey extensions service in County Down covers Bangor, Newtownards, Newry and Banbridge and more.

Homes in County Down

Across Northern Ireland you find city terraces, suburban semis and rural bungalows and farmhouses, so the right approach depends on the plot and the planning history.

What do you get with a double-storey extension?

A double-storey extension adds new rooms on both the ground and first floor in one build, typically a larger kitchen or living space downstairs and an extra bedroom or bathroom above. Because the roof and foundations are shared, the cost per square metre is usually lower than a single-storey extension.

Planning and building control applications to the council
Foundations, steelwork, brick and block walls, roof
Windows, insulation, plastering, electrics and plumbing

How much should I budget for a double-storey extension?

Guide prices for double-storey extensions, including VAT where it applies. Your fixed price is confirmed in writing after the survey.

Double-storey extensions	Guide price incl. VAT
Standard specification	£2,400 to £2,900 per m²
Good specification	£2,900 to £3,400 per m²
High specification	£3,400 to £3,850 per m²

Planning and building rules in County Down

Projects in Northern Ireland need planning clearance from one of the eleven councils and building control approval, also from the council. The Party Wall etc. Act does not extend to Northern Ireland, so work near neighbours is agreed directly and documented carefully.

Two-storey extensions in Northern Ireland normally need planning permission from the council, plus building control approval.

What should County Down homeowners check first?

The new roof is tied into the old one, so roof tiles and ridge details need to match.
The first-floor link can mean moving a bathroom or reshaping the landing.

What happens after I enquire?

Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
Survey at your house. We look at the existing structure, services and access, and agree what the design needs to achieve.
Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
Construction and completion. One site lead co-ordinates every trade through to the building control certificate.

What people ask before starting

How much does a two-storey extension cost?

Typically about £2,400 to £3,850 per square metre of new floor area including VAT. A 40 m² extension across two floors is often around £100,000 to £150,000 depending on specification.

How long does a two-storey extension take?

Around 14 to 24 weeks on site, plus the planning period before that.

How do I get a price for double-storey extensions in County Down?

Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.

Double-storey extensions in nearby towns

Learn more about double-storey extensions, or see every project we cover in County Down.