Part single, part two-storey extensions in Newcastle

Before you start in Newcastle, here's what applies.

Postcode districts: BT31 and BT33
County / area: County Down, Northern Ireland
Price region: Northern Ireland
Guide price: £63,500–£87,000 (£1,760–£2,420 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 part single, part two-storey extension

A part single, part two-storey extension is an extension where the ground floor is wider or deeper than the floor above, so only part of it rises to two storeys. It usually gives a large kitchen or living area with roof lights below and one bedroom or bathroom above. It is often a good way to add space while limiting the effect on neighbours.

Newcastle sits about 31.9 miles from Bangor (County Down). Closer to home, Downpatrick is 10.4 miles away and Kilkeel 11.7 miles.

What it costs in Newcastle

Using our Northern Ireland rates, a part single, part two-storey extension with a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) comes to about £63,500–£87,000, including VAT. Bigger or more glazed designs cost more per m². Professional fees for drawings and the structural engineer are listed separately on our prices page.

Spec	Per m²	A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total)
Essential	£1,620–£2,230 per m²	£58,500–£80,000
Standard	£1,760–£2,420 per m²	£63,500–£87,000
Premium	£2,110–£2,900 per m²	£76,000–£104,500

Planning and building control in Newcastle

In Northern Ireland, the extension can be permitted development if it 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 met. Specified protected areas are excluded. If the design goes further, a planning application costs £347 per dwelling, and building control approval is needed either way.

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

The roof junction

Where the single-storey roof meets the two-storey wall you need a sound weathering detail, usually a lead or similar flashing, and enough height for roof lights or a lantern. We set the roof falls and the upstairs window sill heights together so they do not clash.

Where to put the two-storey part

The two-storey section usually works best away from the closest neighbour, with the single-storey part on that boundary side. We test a few positions against neighbours' windows, the upstairs layout and the roof shape before choosing the one to take forward.

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.
Design and approvals
We draw the extension and check it against the rules for Northern Ireland, then apply for planning permission or a certificate of lawfulness, whichever fits.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.

Questions about part single, part two-storey extensions in Newcastle

How much does a part single, part two-storey extension cost in Newcastle?

Our guide for Northern Ireland, which covers Newcastle, is £1,760–£2,420 per m² including VAT. A typical project with a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) comes to about £63,500–£87,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Who handles building control for a project in Newcastle?

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 part single, part two-storey 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.

Can the single-storey part be deeper than the two-storey part?

With planning permission, yes, and that is often the point of the design: the ground floor projects further into the garden while the first floor stays back from neighbours. Under permitted development, the depth limits for extensions of more than one storey can apply to the whole extension, so we confirm which route applies before drawings are finalised.

Which side should the two-storey part go on?

Usually the side furthest from the nearest neighbour's windows, so the single-storey part sits nearest them and keeps their light. Other factors are where the stairs land upstairs, which room needs the extra space and where drains run. We sketch options at the design stage and explain which is most likely to be approved.

Nearby

Nearby towns we cover for part single, part two-storey extensions:

Other extensions in Newcastle

All two-storey extension services in Newcastle · Part single, part two-storey extensions across County Down

Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.