House extensions in Belfast
Planning an extension in Belfast? Compare extension types, see guide prices adjusted for Belfast and book a free site visit.
- Postcode districtsBT1, BT2, BT6, BT7, BT12, BT13
- Price regionNorthern Ireland (×0.86)
- Planning rulesNorthern Ireland
- Site visitFree, no obligation
Approvals for an extension in Belfast
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.
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.
Belfast extension prices at a glance
Prices on this page use our Northern Ireland factor of ×0.86, include VAT at 20% and cover the build; your written price follows a survey and agreed drawings.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Extensions over a garage | 12 m² | £21,500 – £28,000 |
| Orangery extensions | 16 m² | £38,500 – £48,500 |
| Wraparound extensions | 25 m² | £49,000 – £62,500 |
| Single-storey rear extensions | 20 m² | £35,000 – £45,000 |
| Side return extensions | 11 m² | £22,500 – £28,500 |
| Conservatory replacement extensions | 14 m² | £25,500 – £33,500 |
| Double-storey extensions | 32 m² | £49,500 – £65,000 |
Choosing the right extension in Belfast
Northern Ireland's housing ranges from city terraces to large numbers of detached houses and bungalows on rural plots, many in render, where single-storey extensions fit easily.
Start by comparing bungalow extensions, side extensions and annexe extensions: between them they cover most of the layouts we see requested for houses like these.
Areas we cover around Belfast
We cover Belfast and the postcode districts BT1, BT2, BT6, BT7, BT12, BT13. The same team covers Castlereagh (2 miles), Newtownabbey (4 miles), Lisburn (7 miles), Carrickfergus (10 miles), Antrim (14 miles), all within easy reach. Newtownards, in County Down, is roughly 9 miles from Belfast and also on our list.
Choose an extension type
- Planning permission for extensions · from £300
- Extension plans and drawings · from £1,000
- Kitchen extensions · from £23,000
- Single-storey rear extensions · from £18,000
- Side extensions · from £18,500
- Wraparound extensions · from £30,500
- Double-storey extensions · from £32,500
- Utility and boot room extensions · from £12,000
- Porch extensions · from £3,400
- Flat roof extensions · from £18,000
- Building regulations for extensions · from £750
- Side return extensions · from £15,000
- Timber frame extensions · from £18,000
- Home office extensions · from £13,500
- Conservatory replacement extensions · from £17,000
- Pitched roof extensions · from £19,000
- Annexe extensions · from £47,000
- Orangery extensions · from £25,500
- Bedroom extensions · from £22,000
- Extensions over a garage · from £20,500
- Glass box extensions · from £25,500
- Bungalow extensions · from £22,500
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
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
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
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 Belfast
How much does an extension cost in Belfast?
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 you cover all of Belfast?
Yes, including the surrounding parts of County Antrim. Site visits are free and there is no obligation.
Will my neighbours need to be told?
If you apply for planning permission the council notifies neighbours, and we agree access with them in writing for work near a shared boundary.
Do I need planning permission for an extension in Belfast?
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 Belfast
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.