House extensions in Derry/Londonderry
We design and build house extensions for homes in Derry/Londonderry and the surrounding County Londonderry area, with guide prices adjusted for the region.
- Postcode districtsBT48
- Price regionNorthern Ireland (×0.86)
- Planning rulesNorthern Ireland
- Site visitFree, no obligation
Covering Derry/Londonderry and nearby
Site visits are available across Derry/Londonderry (BT48). Neighbouring towns we cover include Limavady (15 miles), Coleraine (27 miles), Magherafelt (31 miles). For homes towards County Tyrone, Strabane is around 13 miles away.
What works best for Derry/Londonderry houses?
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, single-storey rear extensions and bungalow extensions are often the strongest options, with annexe extensions worth considering where there is room.
Derry/Londonderry extension prices at a glance
We publish guide prices so you can budget before anyone visits. For Derry/Londonderry they are adjusted by ×0.86, the factor we use across Northern Ireland.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Wraparound extensions | 25 m² | £49,000 – £62,500 |
| Conservatory replacement extensions | 14 m² | £25,500 – £33,500 |
| Extensions over a garage | 12 m² | £21,500 – £28,000 |
| Double-storey extensions | 32 m² | £49,500 – £65,000 |
| Side return extensions | 11 m² | £22,500 – £28,500 |
| Kitchen extensions | 20 m² | £36,000 – £46,000 |
Planning rules in Derry/Londonderry
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.
Applications are decided by your council, which handles local planning in Northern Ireland.
Choose an extension type
- Orangery extensions · from £25,500
- Utility and boot room extensions · from £12,000
- Extension plans and drawings · from £1,000
- Timber frame extensions · from £18,000
- Planning permission for extensions · from £300
- Side return extensions · from £15,000
- Glass box extensions · from £25,500
- Home office extensions · from £13,500
- Side extensions · from £18,500
- Building regulations for extensions · from £750
- Double-storey extensions · from £32,500
- Bungalow extensions · from £22,500
- Pitched roof extensions · from £19,000
- Single-storey rear extensions · from £18,000
- Flat roof extensions · from £18,000
- Conservatory replacement extensions · from £17,000
- Annexe extensions · from £47,000
- Porch extensions · from £3,400
- Kitchen extensions · from £23,000
- Extensions over a garage · from £20,500
- Wraparound extensions · from £30,500
- Bedroom extensions · from £22,000
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Questions about extensions in Derry/Londonderry
How much does an extension cost in Derry/Londonderry?
Using our Northern Ireland factor (×0.86), a standard-spec single-storey extension of 20 m² is a guide £35,000 to £45,000 including VAT, and a 32 m² two-storey extension £49,500 to £65,000. Your written price follows the survey.
Do I need planning permission for an extension in Derry/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.
Do you cover all of Derry/Londonderry?
Yes, including the surrounding parts of County Londonderry. Site visits are free and there is no obligation.
How long does an extension take in Derry/Londonderry?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
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.
Book a free site visit in Derry/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.