Two-storey extensions in County Down
We cover all of County Down for two-storey and first-floor extensions. Pick a town or an extension type below.
County Down at a glance
- Nation
- Northern Ireland
- Price region
- Northern Ireland
- Postcode areas
- BT
- Main town
- Bangor (County Down)
- Towns listed
- 15
- Site visits
- Free, no obligation
Choose your town
- Bangor (County Down)
- Newtownards
- Newry
- Banbridge
- Dundonald
- Holywood
- Downpatrick
- Comber
- Carryduff
- Warrenpoint
- Newcastle
- Donaghadee
- Dromore (County Down)
- Kilkeel
- Ballynahinch
Guide prices in Northern Ireland
| Extension type | Per m² | Typical project |
|---|---|---|
| Two-storey rear extension | £1,760–£2,380 per m² | £49,500–£66,500 |
| Two-storey side extension | £1,800–£2,420 per m² | £76,000–£101,500 |
| Two-storey wraparound extension | £1,890–£2,600 per m² | £106,000–£145,500 |
| Part single, part two-storey | £1,760–£2,420 per m² | £63,500–£87,000 |
| Extension over a garage | £1,540–£2,240 per m² | £27,500–£40,500 |
| First-floor extension over an existing single storey | £1,580–£2,290 per m² | £22,000–£32,000 |
| Two-storey front extension | £1,940–£2,640 per m² | £23,000–£31,500 |
Including VAT, Standard spec. See all prices and fees.
Towns in County Down include Bangor (County Down) (BT19), Newtownards (BT22), Newry (BT35), Banbridge (BT32), Dundonald (BT16), Holywood (BT18), Downpatrick (BT30) and Comber (BT23). If yours isn't listed, we still cover it.
Which type suits your house?
Start with what you need the space for. Bedrooms and an en-suite upstairs with a bigger kitchen below is the classic two-storey brief, but in County Down we also design annexes, home offices and bedrooms over garages.
The rules in Northern Ireland
County Down is in Northern Ireland. Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Most others need planning permission. Planning application for works to a house: £347. Councils aim to decide local applications within an average of 15 weeks; many take longer.
The full Northern Ireland rules explained
Extension types
- Two-storey rear extensions
- Two-storey side extensions
- Two-storey wraparound extensions
- Part single, part two-storey extensions
- Extensions over a garage
- First-floor extensions
- Two-storey front extensions
By house type
- Two-storey extensions for semi-detached houses
- Two-storey extensions for detached houses
- Two-storey extensions for end-of-terrace houses
Rooms and uses
- Kitchen extensions with bedrooms above
- Extra bedroom and en-suite extensions
- Two-storey annexe extensions
- Garage conversions with a room above
Design and approvals
- Two-storey extension plans and drawings
- Planning permission for two-storey extensions
- Structural engineering for two-storey extensions
- Building regulations for two-storey extensions
- Design and build two-storey extensions
Questions about extensions in County Down
How much does a two-storey extension cost in County Down?
In Northern Ireland our guide for a two-storey rear extension is £1,760–£2,380 per m² including VAT, about £49,500–£66,500 for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Side and wraparound extensions cost a little more per m².
Do I need planning permission in County Down?
Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Most others need planning permission. Planning application for works to a house: £347.
Do you cover the whole of County Down?
Yes. We list the main towns here, but we cover the whole of County Down including villages. The first site visit is free.
What happens at the first visit?
We look at your house, the boundaries, access and drains, talk through what you need and explain the approvals. Then we price the design stage, including the measured survey, in writing.