Extensions over a garage in Carrickfergus

What we'd confirm first for a project in Carrickfergus.

Postcode districts: BT38
County / area: County Antrim, Northern Ireland
Price region: Northern Ireland
Guide price: £27,500–£40,500 (£1,540–£2,240 per m²)
Approval route: Planning permission is needed: permitted development side extensions in Northern Ireland can't be more than 4 m high, which rules out two storeys.
Nearest towns: Greenisland (2.9 miles), Jordanstown (4.4 miles), Holywood (5.4 miles)
Distance to Belfast: about 9.5 miles
First visit: Free, no obligation

About an extension over a garage

An extension over a garage is a new first-floor room built on top of an existing attached garage, usually a bedroom, en-suite or study. It uses a footprint you already have, so it adds floor space without taking any garden. The garage walls and foundations often need strengthening or replacing to carry the new floor.

We cover Carrickfergus (BT38) and the places around it, including Greenisland (2.9 miles), Jordanstown (4.4 miles) and Holywood.

What it costs in Carrickfergus

Guide prices for extensions over a garage in Northern Ireland are around £1,540–£2,240 per m² of new floor space, including VAT. For a typical project with 3 m × 6 m of new first-floor space (18 m²), that's roughly £27,500–£40,500. The fastest way to a firmer number is a free site visit, after which we price the design stage in writing.

Spec	Per m²	3 m × 6 m of new first-floor space (18 m²)
Essential	£1,420–£2,060 per m²	£25,500–£37,000
Standard	£1,540–£2,240 per m²	£27,500–£40,500
Premium	£1,850–£2,690 per m²	£33,500–£48,500

Planning and building control in Carrickfergus

In Northern Ireland, permitted development for two-storey work is set out for rear extensions, so building over a side garage normally needs a planning application, which costs £347 per dwelling. Councils aim for an average of 15 weeks for local applications. Building control approval is also needed, including fire separation if the garage stays in use.

Approval in Northern Ireland: Planning application for works to a house: £347. Councils aim to decide local applications within an average of 15 weeks; many take longer.

Building control: Building control approval from the local council under the Building Regulations (Northern Ireland), using the Technical Booklets.

Design points for Carrickfergus homes

Fire separation

If the garage stays a garage, the floor between it and the room above, and any door into the house, must give fire separation under building regulations. That usually means fire-resisting plasterboard ceilings, sealed gaps and a fire door, which we design in from the start.

Matching the house

A room over a garage usually sits beside the front of the house in full view, so roof form, ridge height, windows and brick matter. Setting the front wall and ridge back slightly from the main house usually helps it look as if it belongs.

How we'd run your project

Visit and first ideas
One of our team visits your house in Carrickfergus, checks the walls, roof and drains, and sketches out options with you.
Design and approvals
We draw the extension and check it against the rules for Northern Ireland, then apply for planning permission or a certificate of lawfulness, whichever fits.
Engineer it
Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.

Questions about extensions over a garage in Carrickfergus

Which postcodes do you cover around Carrickfergus?

We cover Carrickfergus (BT38) and nearby places including Greenisland, Jordanstown and Holywood, plus the rest of County Antrim. The first site visit is free.

How long does an extension over a garage take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils aim to decide local applications within an average of 15 weeks; many take longer), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

Do I need planning permission for an extension over a garage in Carrickfergus?

Carrickfergus is in Northern Ireland. Planning permission is needed: permitted development side extensions in Northern Ireland can't be more than 4 m high, which rules out two storeys.

How do I get into a room over the garage?

Usually through a new opening off the existing landing or a bedroom, so the stairs stay where they are. If the floor levels do not match, a step or two may be needed inside the new room. Where a landing opening is not practical, a new stair from a converted garage is an option.

Can my garage take a room on top?

Sometimes, but it needs checking. Many garages are built on shallow footings with thin walls, designed only for a single storey. We dig a trial hole and inspect the walls, and the structural engineer decides whether to reuse them, strengthen them, underpin the footings or build new foundations inside the garage.

Nearby

Close to Carrickfergus? We work across the area, including:

Other extensions in Carrickfergus

All two-storey extension services in Carrickfergus · Extensions over a garage across County Antrim

Want a figure first? Try our guide price tool, then book a free visit to firm it up.