Downpatrick, County Down
Single-storey rear extension in Downpatrick
We plan and build single-storey rear extensions for homeowners in Downpatrick. Ground-floor space across the back of the house, usually for a kitchen, dining or family room. Start with a free site visit, then a written price once the design is agreed.
Downpatrick is covered from our County Down round, including BT30. A single-storey rear extension in Downpatrick is mostly built from the garden side, so the house stays usable for most of the job.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a single-storey rear extension cost in Downpatrick?
In Downpatrick, our guide for a single-storey rear extension is £1,650–£2,700 per square metre including VAT for a standard specification. Northern Ireland prices are the lowest in our range.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £20,000–£32,500 |
| 4 m wide × 5 m deep (20 m²) | £33,000–£54,000 |
| 4 m wide × 6 m deep (24 m²) | £39,500–£64,500 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission for a single-storey rear extension in Downpatrick?
Here is how the rules in Northern Ireland apply to a single-storey rear extension in Downpatrick.
In Northern Ireland the Planning (General Permitted Development) Order (Northern Ireland) 2015 allows a single-storey rear extension of up to 3 metres on an attached house or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres within 2 metres of a boundary. Building control approval from the council is still required.
Northern Ireland has no larger-extension prior approval route; anything beyond permitted development needs a planning application.
Conservation areas, Areas of Outstanding Natural Beauty and listed buildings restrict permitted development in Northern Ireland. At the first visit we measure what is there now and tell you which route fits: permitted development or a planning application.
What are homes in Downpatrick like to extend?
Semis and detached houses are typical of Downpatrick, and many have room for a rear extension within Northern Ireland's permitted development limits.
How a single-storey rear extension in Downpatrick comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Approvals
Permitted development check or planning application, then building control drawings to the Northern Ireland Technical Booklets and structural calculations, plus a written agreement with neighbours for any shared-wall work.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Single-storey rear extensions near Downpatrick
From Downpatrick, the nearest places we also cover are Castlereagh (18.3 miles) and Newtownards (18.3 miles).
- Single-storey rear extension in Castlereagh
- Single-storey rear extension in Newtownards
- Single-storey rear extension in Dundonald
- Single-storey rear extension in Lisburn
- Single-storey rear extension in Belfast
Other work in Downpatrick:
FAQ
Single-storey rear extension questions in Downpatrick
How long does a rear extension take to build in Downpatrick?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Can you match the brick or stone on my Downpatrick house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Does it add value to the house?
Nationwide's October 2025 house price research found that a 10% increase in floor area is linked to about 5% higher value on average. It is a guide, not a promise; local agents can tell you what extended homes on your street sell for.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
Who will build my extension?
Vetted building teams working under contract to us. Your contract is with S&K Property Investments and Improvement Ltd for the design and the build.