County Londonderry house extensions
More space without moving: we plan and build extensions across County Londonderry, with one team for the drawings, the council and the build.
- Towns listed4
- Price regionNorthern Ireland (×0.86)
- Planning rulesNorthern Ireland
- Postcode districts9
Towns we cover in County Londonderry
Towns we cover here include Derry/Londonderry, Coleraine, Limavady, Magherafelt.
Which extension suits a County Londonderry home?
In Northern Ireland, extension projects follow the NI planning rules and council building control, which we account for from the first survey.
Depending on the plot, bungalow extensions and side extensions are often the strongest options, with annexe extensions worth considering where there is room.
County Londonderry extension prices at a glance
Every figure below is a guide for County Londonderry, adjusted for Northern Ireland build costs (×0.86) and including VAT. Design and council fees are shown separately on each page.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Extensions over a garage | 12 m² | £21,500 – £28,000 |
| Side return extensions | 11 m² | £22,500 – £28,500 |
| Single-storey rear extensions | 20 m² | £35,000 – £45,000 |
| Conservatory replacement extensions | 14 m² | £25,500 – £33,500 |
| Kitchen extensions | 20 m² | £36,000 – £46,000 |
Do extensions in County Londonderry need planning permission?
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.
In a conservation area or area of townscape character the permitted development rights are more limited, listed homes need listed building consent, and if rights have been removed by a condition, any extension needs an application.
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.
Every extension type in County Londonderry
- Single-storey rear extensions · from £18,000
- Side extensions · from £18,500
- Wraparound extensions · from £30,500
- Kitchen extensions · from £23,000
- Bedroom extensions · from £22,000
- Planning permission for extensions · from £300
- Glass box extensions · from £25,500
- Timber frame extensions · from £18,000
- Side return extensions · from £15,000
- Porch extensions · from £3,400
- Annexe extensions · from £47,000
- Flat roof extensions · from £18,000
- Utility and boot room extensions · from £12,000
- Building regulations for extensions · from £750
- Pitched roof extensions · from £19,000
- Conservatory replacement extensions · from £17,000
- Orangery extensions · from £25,500
- Extension plans and drawings · from £1,000
- Double-storey extensions · from £32,500
- Bungalow extensions · from £22,500
- Home office extensions · from £13,500
- Extensions over a garage · from £20,500
Neighbouring areas
Questions about extensions in County Londonderry
How much does an extension cost in County Londonderry?
With our Northern Ireland factor (×0.86), a standard-spec 20 m² single-storey extension is a guide £35,000 to £45,000 including VAT. Prices for every type are linked on this page.
Do you cover all of County Londonderry?
Yes, across the whole of County Londonderry. Site visits are free and there is no obligation.
Who do I contract with?
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 planning permission for an extension in County Londonderry?
Not always. It depends on the size, position and your property's history. In Northern Ireland some single-storey rear extensions are permitted development; larger ones need planning permission.
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.