Double-storey extensions for homes in Coleraine
Thinking about a double-storey extension for your Coleraine home? Start with a free site visit: we measure up, check what the council will allow and give you honest guide figures on the day.
- Guide price in ColeraineFrom £32,500 inc VAT
- PlanningUsually needs planning permission
- Build time16–24 weeks on site
- Postcode districtsBT52
Planning rules that apply in Coleraine
In Northern Ireland the Planning (General Permitted Development) Order 2015 lets some single-storey rear extensions go ahead without planning permission, up to 3 m on a semi-detached or terraced house and 4 m on a detached house, within height and boundary limits. Larger, side and two-storey extensions normally need planning permission from the council, and building control approval is separate.
Homes in conservation areas, areas of townscape character and listed buildings have tighter rules, so we always check the property's status and planning history before design starts.
Northern Ireland has no Party Wall Act. Where work is on or close to a shared boundary, we agree access and protection with your neighbour in writing before work starts.
Applications are decided by your council, which handles local planning in Northern Ireland.
Local to Coleraine
We cover Coleraine and the postcode districts BT52. We also work in nearby Limavady (13 miles), Magherafelt (26 miles), Derry/Londonderry (27 miles).
Ballymena, in County Antrim, is roughly 24 miles from Coleraine and also on our list. In Northern Ireland, extension projects follow the NI planning rules and council building control, which we account for from the first survey.
How much does a double-storey extension cost in Coleraine?
Prices below are for Coleraine, using the Northern Ireland factor of ×0.86. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Coleraine: £1,330 to £2,580 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m, two floors 24 m² | £32,500 – £39,500 | £37,000 – £49,000 | £47,000 – £62,000 |
| 4 m × 4 m, two floors 32 m² | £42,500 – £51,000 | £49,500 – £65,000 | £63,000 – £83,000 |
| 4 m × 6 m, two floors 48 m² | £63,500 – £76,500 | £74,000 – £97,500 | £94,500 – £124,000 |
Want a range for your exact size? The guide-price tool takes about a minute.
What we take care of
- Householder planning application where needed
- Breaking through at both levels, stairs and landing changes where needed
- Building regulations drawings and structural design
- Ground and first floor structure, roof tied into the existing roof
- Measured survey, design and planning drawings
The roof is what makes a two-storey extension look right or wrong. We match the pitch and materials of the main house wherever possible and plan the upstairs layout around the existing landing so the new rooms feel original rather than bolted on.
How the project works
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
We visit your Coleraine home, measure up, talk through what you want and check the planning position.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Your questions about a double-storey extension in Coleraine
How long does a double-storey extension take to build in Coleraine?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 8–16 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Coleraine, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do you cover all of Coleraine?
Yes. We cover Coleraine and the surrounding parts of County Londonderry. Site visits are free and there is no obligation.
Is a two-storey extension cheaper per square metre?
Usually. Our guide range is about £1,330 to £2,580 per m² of new floor area including VAT, compared with £1,500 to £2,920 per m² for single-storey work, because the foundations and roof are shared across two floors.
Book a free site visit in Coleraine
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.