In short: An HMO extension adds space to a shared house, usually a ground-floor bedroom with ensuite or a bigger communal kitchen. We carry this out across County Antrim, priced against the HMO rules for Northern Ireland and the council’s own standards.
- Nation
- Northern Ireland
- Pricing region
- Northern Ireland
- Postcode areas
- BT
- Main towns
- Lisburn, Newtownabbey, Castlereagh, Carrickfergus, Ballymena
What do extensions for extra rooms in County Antrim involve?
- Planning route check and drawings
- Building control completion
- Foundations, structure and roof
- Ensuite drainage and extraction
- Kitchen or bedroom fit-out
- Fire separation and detection extended to the new space
Which rules apply in County Antrim?
- All new HMOs need planning permission; councils such as Belfast apply HMO policy areas and limits on concentration.
- New HMOs need building control approval as well as planning permission.
- The NIFRS HMO Fire Safety Guide (July 2026) usually expects Grade D1 interlinked detection in smaller shared houses and a Grade A system with more than 6 occupants or over 200 m².
- Kitchens, bathrooms and WCs must meet the 2019 living accommodation standard regulations and licence conditions.
- Doors on protected routes are typically FD30 or FD30S, self-closing on three hinges; emergency lighting is required in HMOs of 4 or more storeys.
In Northern Ireland, licensing is run centrally by the NI HMO Unit, and all new HMOs need planning permission and building control approval from the local council.
How much do extensions for extra rooms cost in County Antrim?
| Item | UK typical | Local guide | Per |
|---|---|---|---|
| Single-storey extension, about 15 m² | £35,000 – £60,000 | £31,500 – £54,000 | project |
| Single-storey extension per m² | £1,800 – £4,000 | £1,600 – £3,600 | m² |
Typical time on site: 8–14 weeks. For a figure for your house, try the guide-price tool.
Extensions for extra rooms by town in County Antrim
Questions about extensions for extra rooms in County Antrim
Can I extend an HMO under permitted development?
Some extensions to houses are permitted development, but rules differ for HMOs and by nation and council. We check the address before design.
Do you handle building control?
Yes, from application to completion certificate.
Do you carry out extensions for extra rooms across County Antrim?
Yes, across the whole of County Antrim, including Lisburn, Newtownabbey, Castlereagh.
Who licenses HMOs in County Antrim?
HMO licensing in County Antrim, as everywhere in Northern Ireland, is run by the NI HMO Unit at Belfast City Council. Planning and building control are handled by the local council.
Other HMO services in County Antrim
- Loft conversions for extra rooms in County Antrim
- Communal kitchen refits in County Antrim
- Layout changes and room reconfiguration in County Antrim
- Large HMO conversions (7+ sharers) in County Antrim
- Ensuite installation in County Antrim
- House to HMO conversion in County Antrim
- Professional and co-living HMO refurbs in County Antrim
- Fire alarm and detection systems in County Antrim