The 10 extension builders from Google's results for Belfast, ranked on Google rating, online presence and other factors. Updated 10 September 2026.
Northern Ireland has separate planning and building control.
on GoogleBelfast
Renovations & Extensions is a Belfast building firm that adds house extensions and renovates kitchens, bedrooms and bathrooms for homes in Belfast and across Northern Ireland. The team works alongside architects and building control, handling everything from foundations and structural work to the internal finishes.
on GoogleBelfast
Madden Contracts constructs home extensions for property owners throughout Belfast. The firm provides structural building services to help local clients expand their available living space.
028 9081 7200 55 - 59 Adelaide St, Belfast BT2 8FE
on GoogleBelfast
Line Architects undertakes architectural design and feasibility studies for detached house extensions in Belfast. The practice develops plans to alter internal room configurations and expand residential accommodation.
028 9532 0034 51 Haddington Gardens, Belfast BT6 0AN
on GoogleLisburn
Knox Clayton delivers architectural services for private homes and house extensions in Lisburn and Belfast. The practice designs bright, open-plan living environments and larger residential layouts.
028 9267 4312 2A Wallace Ave, Lisburn BT27 4AA
on GoogleDungiven, Londonderry
Farren Architects designs house extensions and reconfigurations, creating open-plan kitchen and living spaces. Work includes single-storey extensions, glazed openings, carports and patio areas. The practice undertakes projects in Belfast and across Northern Ireland.
028 7774 0643 447 Ballyquin Rd, Dungiven, Londonderry BT47 4LX
on GoogleBelfast
Planning a House Extension in Belfast provides guidance and construction services for residential extensions across Northern Ireland. The business handles building projects that add living space to homes. It covers planning permission and building regulations requirements throughout the Belfast area.
07446 950762 Office 3:01, Innovation Factory, 385 Springfield Rd, Belfast BT12 7DG
on GoogleBelfast
Jim Morrison Architects plans home and kitchen extensions for residential clients in Belfast. The architectural practice creates designs for house alterations, reconfigurations and property renovations. It works directly with homeowners to expand and alter living spaces across the city.
07980 302885 31 Cricklewood Park, Belfast BT9 5GW
on GoogleBallymote, Downpatrick
Creative Construction NI builds home extensions, sunrooms and garden rooms throughout Downpatrick and Northern Ireland. Its work includes conservatory roof replacements, new home builds, property renovations, and window and door installations.
028 4489 8098 Unit 5, Upper, 2 Ballynoe Rd, Ballymote, Downpatrick BT30 8AG
on GoogleAdvantage Wy, Belfast
Total Home Improvements builds house extensions and installs windows and doors across Belfast and Northern Ireland. Its fitting services cover casement, sash and tilt-and-turn windows alongside bifold, patio and composite doors.
028 9072 9688 Ind Est, Unit 2 Ballygomartin, Advantage Wy, Belfast BT13 3LZ
Belfast
Techniplan is a Belfast architectural consultancy providing design services for property conversions, home extensions and renovations. The firm manages planning permission applications and building regulation guidance for projects across Northern Ireland.
07767 271305 40 Mount Merrion Park, Belfast BT6 0GB
In Belfast, single storey, per m² typically costs £1,600 – £2,200. Labour in County Antrim runs 12% below the UK median, which accounts for most of the difference from the same job elsewhere.
These are the firms from Google's results for "house extensions belfast". They are ranked on Google rating, online presence and other factors.
The figures above are Belfast ranges. These explain what drives them, so you can read a quote properly.
Per-square-metre prices for single-storey, two-storey, side return and kitchen extensions, costs by size, the fees outside the build price, and planning limits by nation.
The permitted development limits for extensions, lofts, porches and outbuildings in England, where the rights do not apply, what prior approval and a certificate cost, and how Wales, Scotland and NI differ.
When the Party Wall Act applies, which notice to serve and how far ahead, what your neighbour can do, what a surveyor's award costs, and the rules in Scotland and NI.
Under permitted development, three metres for a terrace or semi and four for a detached, doubled to six and eight under the prior approval process. Height, materials and how much garden you cover all carry separate limits, and none of it applies in a conservation area.
If you are excavating within three metres of a neighbour's foundations or building on the boundary, yes. You must serve notice two months before work starts. Skipping it is the most common reason extension projects stall.