Extensions over a garage in Dumbarton

Quick reference for homeowners in Dumbarton.

Postcode districts: G82
County / area: Glasgow and Dunbartonshire, 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: Vale of Leven (1.9 miles), Bonhill (2.4 miles), Alexandria (3.5 miles)
Distance to Glasgow: about 13.3 miles
First visit: Free, no obligation

About an extension over a garage

An extension over a garage suits you if you have an attached single garage beside the house and need an extra bedroom or a larger main bedroom with an en-suite. You get an inspection of the garage structure, a design that matches the house, the approvals your nation needs, structural design, a building warrant and the build, carried out by vetted teams working under S&K.

Dumbarton sits about 13.3 miles from Glasgow. Closer to home, Vale of Leven is 1.9 miles away and Bonhill 2.4 miles.

What it costs in Dumbarton

Expect an extension over a garage in Dumbarton to land somewhere around £29,500–£43,000 for 3 m × 6 m of new first-floor space (18 m²). Our Scotland guide rate is £1,640–£2,400 per m², including VAT. Keep a contingency of around 10% for things nobody can see until the ground is opened up.

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 Dumbarton

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 Dumbarton 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 Dumbarton, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Dumbarton.
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.
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 Dumbarton

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

Our guide for Scotland, which covers Dumbarton, 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.

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.

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

Dumbarton 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.

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.

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 Dumbarton? We work across the area, including:

Other extensions in Dumbarton

All two-storey extension services in Dumbarton · Extensions over a garage across Glasgow and Dunbartonshire

Book a free site visit in Dumbarton and we'll tell you what's possible, what approvals you need and what the design stage would cost.