HMO extensions across County Down

In short: An HMO extension adds space to a shared house, usually a ground-floor bedroom with ensuite or a bigger communal kitchen. In County Down we survey first, price each item separately and hand over the certificates and photos a council asks for.

Nation: Northern Ireland
Pricing region: Northern Ireland
Postcode areas: BT
Main towns: Bangor (County Down), Banbridge, Holywood

What do extensions for extra rooms in County Down involve?

Fire separation and detection extended to the new space
Planning route check and drawings
Foundations, structure and roof
Heating, insulation and glazing
Party wall coordination where needed
Ensuite drainage and extraction

Which rules apply in County Down?

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 Down?

Regional adjustment for Northern Ireland. Planning budgets: see our prices page.
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 Down

Questions about extensions for extra rooms in County Down

Is a kitchen extension worth it?

Often, when the existing kitchen limits how many people the council will allow. A bigger kitchen can unlock an extra room.

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 carry out extensions for extra rooms across County Down?

Yes, across the whole of County Down, including Bangor (County Down), Banbridge, Holywood.

Who licenses HMOs in County Down?

HMO licensing in County Down, 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.

Extensions for extra rooms across County Down

What do extensions for extra rooms in County Down involve?

Which rules apply in County Down?

How much do extensions for extra rooms cost in County Down?

Extensions for extra rooms by town in County Down

Questions about extensions for extra rooms in County Down

Other HMO services in County Down

Planning HMO works?