Extensions over a garage in Perth and Kinross

Perth and Kinross at a glance

Nation: Scotland
Price region: Scotland
Postcode areas: KY, PH
Towns covered: 8 listed below, plus surrounding villages
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.
Site visits: Free, no obligation

What an extension over a garage involves

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.

Across Perth and Kinross we cover Perth (PH1), Blairgowrie and Rattray (PH10), Crieff (PH5), Auchterarder (PH3), Scone (PH2) and Kinross (KY13), plus the smaller places around them.

Guide price in Scotland

A guide price for Perth and Kinross: 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%. We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.

Spec	Per m²	Typical project
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

Rules in Scotland

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.

There is no Party Wall Act in Scotland. Shared walls and boundaries are governed by title deeds and common law, so we speak to neighbours early and record the condition of shared structures.

Getting the design right

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.

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.

How we work in Perth and Kinross

Understand the brief
At your home in Perth and Kinross we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Drawings, then consent
We draw the scheme, check it against the rules in Scotland, and take it through the right consent with the council.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Finish and certify
Second fix, plastering and making good, then the council's final building standards inspection and the completion paperwork.

Towns we cover in Perth and Kinross

Extensions over a garage in Perth and Kinross: questions

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

In Scotland our guide is £1,640–£2,400 per m² including VAT, so about £29,500–£43,000 for 3 m × 6 m of new first-floor space (18 m²). Essential and Premium specs move that by roughly 8% down or 20% up.

Do I need to convert the garage as well?

No. You can keep the garage for parking or storage and build only the room above, as long as the floor between them and any door into the house meet fire separation rules. Converting the garage at the same time is often good value, because the walls and foundations may be upgraded anyway.

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.

Will I need planning permission in Perth and Kinross?

Perth and Kinross 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.

Neighbouring areas

All extension services in Perth and Kinross · About extensions over a garage