Extensions over a garage in Perth

Quick reference for homeowners in Perth.

Postcode districts: PH1 and PH2
County / area: Perth and Kinross, Scotland
Price region: Scotland
Guide price: £29,500–£43,000 (£1,640–£2,400 per m²)
Approval route: Planning permission is usually needed: Class 1B permitted development only applies if every part of the extension is at least 10 m from all boundaries. A building warrant is needed before work starts.
Nearest towns: Scone (2 miles), Bridge of Earn (3.4 miles), Auchterarder (12.6 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 postcode districts PH1 and PH2 in and around Perth, along with neighbouring Scone, Bridge of Earn and Auchterarder.

What it costs in Perth

A guide price for Perth: around £29,500–£43,000 for 3 m × 6 m of new first-floor space (18 m²). That works out at £1,640–£2,400 per m² of new floor space, including VAT at 20%. Kitchens, bathroom fittings and flooring are priced separately so you can compare like with like.

Spec	Per m²	3 m × 6 m of new first-floor space (18 m²)
Essential	£1,510–£2,210 per m²	£27,000–£39,500
Standard	£1,640–£2,400 per m²	£29,500–£43,000
Premium	£1,970–£2,880 per m²	£35,500–£52,000

Planning and building standards in Perth

In Scotland, a room over a garage makes the extension more than one storey, so Class 1B applies, which needs at least 10 m to every boundary for permitted development. Attached garages are rarely that far from the boundary, so expect a householder application (£371, decided within two months) and a building warrant.

Approval in Scotland: Householder planning application: £371. Councils have two months to decide a local planning application.

Building standards: A building warrant from the council's building standards service before work starts, and a completion certificate at the end. Scotland uses its own Technical Handbooks.

Design points for Perth homes

Checking the garage foundations

Garages are often built on shallow strip footings sized for a single-storey wall and a light roof. A trial hole shows their depth and condition, and the engineer decides whether they can carry two storeys or need underpinning or new foundations inside the garage.

Floor levels and headroom

Garage floors are often lower than the house, and the new first floor may not line up with the existing landing. We set the floor level to avoid awkward steps upstairs, while keeping enough headroom in the garage below for a car or storage.

How we'd run your project

Start at your house
We come to your home in Perth, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in Scotland before drawing in detail.
Technical design
We prepare the building warrant drawings, structural calculations and specification so the build price can be fixed.
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 Perth

How much does an extension over a garage cost in Perth?

Our guide for Scotland, which covers Perth, is £1,640–£2,400 per m² including VAT. A typical project with 3 m × 6 m of new first-floor space (18 m²) comes to about £29,500–£43,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

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

Perth is in Scotland. Planning permission is usually needed: Class 1B permitted development only applies if every part of the extension is at least 10 m from all boundaries. A building warrant is needed before work starts.

How long does an extension over a garage take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils have two months to decide a local planning application), 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.

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.

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.

Nearby

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

Other extensions in Perth

All two-storey extension services in Perth · Extensions over a garage across Perth and Kinross

The quickest next step is a visit. We'll look at your house in Perth and give you an honest view of the options.