Single-storey rear extensions in County Londonderry
We design and build single-storey extensions for houses in County Londonderry, with a written price once the survey and design are done and one point of contact throughout.
- Guide priceFrom £18,000 inc VAT
- PlanningNI permitted development (rear 3–4 m) or planning
- Towns covered4
- Site visitFree, no obligation
Towns in County Londonderry
What we take care of
- Flat or pitched roof, rooflights or lantern
- Building regulations drawings and structural calculations
- Doors, windows, insulation, plastering and first fix to finish
- Planning route checked and the right approval obtained
- Measured survey and design
Depth is the big decision. Every extra metre adds floor area but also takes garden and can push you out of permitted development. We draw the room at two or three depths so you can see the trade-off in space, light and cost before anything is fixed.
Will the council need to approve it?
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.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
In Northern Ireland building control is run by the councils under the Building Regulations (Northern Ireland). We submit full plans or a building notice and book the inspections through to completion.
Applications are decided by your council, which handles local planning in Northern Ireland.
Extensions in and around County Londonderry
Towns we cover in County Londonderry include Derry/Londonderry, Coleraine, Limavady, Magherafelt. In Northern Ireland, extension projects follow the NI planning rules and council building control, which we account for from the first survey.
Single-storey extension prices in County Londonderry
Labour and material costs vary across the UK, so for County Londonderry we use our Northern Ireland factor (×0.86). The ranges include VAT and exclude design, structural and council fees.
Typical rates in County Londonderry: £1,500 to £2,920 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £18,000 – £21,500 | £21,000 – £27,000 | £26,500 – £35,500 |
| 4 m × 5 m 20 m² | £30,000 – £35,500 | £35,000 – £45,000 | £44,500 – £58,500 |
| 5 m × 6 m 30 m² | £45,000 – £53,000 | £52,500 – £67,500 | £67,000 – £88,000 |
Want a range for your exact size? The guide-price tool takes about a minute.
From first visit to completion
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
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Single-storey extension questions answered
Who do I contract with for a single-storey extension in County Londonderry?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Do I need building regulations approval in County Londonderry?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for County Londonderry, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Flat roof or pitched roof?
Flat roofs give more headroom inside and suit lanterns and rooflights; pitched roofs can blend better with older houses. Both meet building regulations when built properly. See our flat roof and pitched roof pages for the details.
How much does a single-storey extension cost per square metre?
Our guide range is about £1,500 to £2,920 per m² including VAT, depending on specification. A standard-spec 4 m × 5 m room usually lands at £35,000 to £45,000 in County Londonderry, plus design and council fees.
Book a free site visit in County Londonderry
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.