First-floor extensions in Greenisland
Our first-floor extensions service in Greenisland covers everything: measured survey, design, planning or permitted development checks, structural design, building control and the build itself.
Greenisland: the key facts for this kind of project.
- Postcode districts
- BT37
- County / area
- County Antrim, Northern Ireland
- Price region
- Northern Ireland
- Guide price
- £22,000–£32,000 (£1,580–£2,290 per m²)
- 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
- Jordanstown (1.6 miles), Carrickfergus (2.9 miles), Newtownabbey (3.1 miles)
- Distance to Belfast
- about 7.5 miles
- First visit
- Free, no obligation
About a first-floor extension
A first-floor extension is a new upstairs room built on top of an existing single-storey part of your house, such as a rear kitchen extension, a utility or a side annexe. It adds a bedroom, bathroom or study without enlarging the footprint. Whether it works depends mainly on whether the walls and foundations below can carry the extra load.
We cover postcode district BT37 in and around Greenisland, along with neighbouring Jordanstown, Carrickfergus and Newtownabbey.
What it costs in Greenisland
Our guide for Northern Ireland is £1,580–£2,290 per m² including VAT. On a project with 4 m × 3.5 m of new first-floor space (14 m²), that puts a first-floor extension in Greenisland at roughly £22,000–£32,000. These are guides, not quotes. Ground conditions, steelwork and access can move the figure either way.
| Spec | Per m² | 4 m × 3.5 m of new first-floor space (14 m²) |
|---|---|---|
| Essential | £1,460–£2,100 per m² | £20,500–£29,500 |
| Standard | £1,580–£2,290 per m² | £22,000–£32,000 |
| Premium | £1,900–£2,750 per m² | £26,500–£38,500 |
Planning and building control in Greenisland
In Northern Ireland, a first floor over a rear extension can be permitted development if the extension goes no more than 3 m beyond the original rear wall and stays at least 7 m from the rear boundary, with height, materials and roof pitch conditions. Over a side extension, or beyond these limits, a planning application 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 Greenisland homes
Tying into the house
The new floor and walls must line up with the existing first floor, often through a new opening in the rear wall above the old one. Floor levels, the position of upstairs windows and the existing roof all affect where the opening can go, so we survey both floors carefully.
Replacing the flat roof
The existing roof usually comes off and is replaced by a new first-floor structure. The room below is exposed for a short time, so we plan temporary weatherproofing and sequence the work to keep the kitchen or living room usable for as long as possible.
How we'd run your project
Measure and listen
A visit to Greenisland to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.
Questions about first-floor extensions in Greenisland
Which postcodes do you cover around Greenisland?
We cover Greenisland (BT37) and nearby places including Jordanstown, Carrickfergus and Newtownabbey, plus the rest of County Antrim. The first site visit is free.
Who handles building control for a project in Greenisland?
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.
Do I need planning permission for a first-floor extension in Greenisland?
Greenisland is in Northern Ireland. 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.
Can I build on top of my existing single-storey extension?
Often yes, but only after the structure has been checked. Foundations, walls and lintels built for one storey may not carry two. We dig trial holes, look for the original building control approval and ask the structural engineer to confirm what can stay, what needs strengthening and what must be rebuilt.
What happens to the room below while the first floor is built?
The old roof is removed, so the room below is exposed for a short period. We fit temporary weather protection, plan the work so the roof comes off only when the new structure is ready, and agree with you which rooms will be out of use and for roughly how long.
Nearby
Other towns near Greenisland:
Other extensions in Greenisland
- Rear
- Side
- Wraparound
- Part two-storey
- Over a garage
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Greenisland · First-floor extensions across County Antrim
Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Greenisland.