First-floor extensions in Portstewart
Thinking about a first-floor extension in Portstewart? We design it, take it through the approvals it needs and build it, with one team responsible from the first visit to the final certificate.
Quick reference for homeowners in Portstewart.
- Postcode districts
- BT55
- County / area
- County Londonderry, 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
- Portrush (2.7 miles), Coleraine (3.8 miles), Ballymoney (11.1 miles)
- Distance to Derry
- about 26.8 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.
Around Portstewart we also work in Portrush, Coleraine and Ballymoney, and across the rest of County Londonderry. Postcode district in and near Portstewart: BT55.
What it costs in Portstewart
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 Portstewart at roughly £22,000–£32,000. Professional fees for drawings and the structural engineer are listed separately on our prices page.
| 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 Portstewart
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 Portstewart homes
Can the existing structure take it?
Many single-storey extensions were built with foundations, walls and lintels sized for one storey. We find out what is there with trial holes and, where available, the original building control drawings. The engineer then decides whether to reuse, strengthen or rebuild parts of the structure.
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
Free site visit
We visit your home in Portstewart, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
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.
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 hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.
Questions about first-floor extensions in Portstewart
Do I need planning permission for a first-floor extension in Portstewart?
Portstewart 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.
Who handles building control for a project in Portstewart?
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.
Which postcodes do you cover around Portstewart?
We cover Portstewart (BT55) and nearby places including Portrush, Coleraine and Ballymoney, plus the rest of County Londonderry. The first site visit is free.
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.
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.
Nearby
Close to Portstewart? We work across the area, including:
Other extensions in Portstewart
- 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 Portstewart · First-floor extensions across County Londonderry
Book a free site visit in Portstewart and we'll tell you what's possible, what approvals you need and what the design stage would cost.