First-floor extensions in Newcastle

What we'd confirm first for a project in Newcastle.

Postcode districts: BT31 and BT33
County / area: County Down, 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: Downpatrick (10.4 miles), Kilkeel (11.7 miles), Ballynahinch (12.7 miles)
Distance to Bangor (County Down): about 31.9 miles
First visit: Free, no obligation

About a first-floor extension

A first-floor extension suits you if your house already has a single-storey extension and you need more space upstairs. You get a structural check of the existing walls and foundations, a design that ties the new floor into the house, the approvals your nation needs, building regulations approval and the build, managed by us and carried out by vetted teams working under S&K.

Around Newcastle we also work in Downpatrick, Kilkeel and Ballynahinch, and across the rest of County Down. Postcode districts in and near Newcastle: BT31 and BT33.

What it costs in Newcastle

A guide price for Newcastle: around £22,000–£32,000 for 4 m × 3.5 m of new first-floor space (14 m²). That works out at £1,580–£2,290 per m² of new floor space, including VAT at 20%. 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 Newcastle

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 Newcastle 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.

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.

How we'd run your project

Free site visit
We visit your home in Newcastle, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in Northern Ireland before drawing in detail.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
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 Newcastle

Do I need planning permission for a first-floor extension in Newcastle?

Newcastle 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.

How long does a first-floor 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.

Which postcodes do you cover around Newcastle?

We cover Newcastle (BT31 and BT33) and nearby places including Downpatrick, Kilkeel and Ballynahinch, plus the rest of County Down. The first site visit is free.

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 Newcastle:

Other extensions in Newcastle

All two-storey extension services in Newcastle · First-floor extensions across County Down

The quickest next step is a visit. We'll look at your house in Newcastle and give you an honest view of the options.