Double-storey extensions in Lisburn

Covering Lisburn

Lisburn is about 7 miles south-west of Belfast. We also cover Belfast (7 miles to the north-east), Newtownabbey and Holywood.

Homes in County Antrim

Northern Ireland has a high proportion of detached houses and bungalows outside the cities, which often suit side extensions, rear extensions and upward extensions.

What is included in a double-storey extension in Lisburn?

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.

Structural engineer’s design and calculations
Windows, insulation, plastering, electrics and plumbing
Joining the new first floor to the existing landing

What will a double-storey extension cost?

Typical ranges for double-storey extensions. Ground conditions, access and specification move the final figure, which we fix in writing before work starts.

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

Do you need permission for a double-storey extension in Lisburn?

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 Lisburn homeowners check first?

Side extensions close to a boundary are often set back or stepped down so they do not create a terraced effect.
The new roof is tied into the old one, so roof tiles and ridge details need to match.

How does the project run?

Start with a conversation. A short call or the online form is enough for us to understand what you want to build.
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.

Questions about a double-storey extension in Lisburn

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.

Is a two-storey extension better value than a single-storey one?

Per square metre, usually yes, because the foundations and roof serve two floors of space.

Who deals with the council for a project in Lisburn?

We do. We prepare the drawings, submit planning or permitted development paperwork if needed, and arrange building control inspections.

Other towns nearby

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