Extensions over a garage in Sinfin

Sinfin: the key facts for this kind of project.

Postcode districts: DE23, DE24 and DE73
County / area: Derbyshire, England
Price region: East Midlands
Guide price: £31,000–£45,000 (£1,720–£2,500 per m²)
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Nearest towns: Derby (2.9 miles), Chaddesden (4 miles), Oakwood (Derbyshire) (4.9 miles)
Distance to Derby: about 2.9 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, building regulations approval and the build, carried out by vetted teams working under S&K.

We cover postcode districts DE23, DE24 and DE73 in and around Sinfin, along with neighbouring Derby, Chaddesden and Oakwood (Derbyshire).

What it costs in Sinfin

Our guide for the East Midlands is £1,720–£2,500 per m² including VAT. On a project with 3 m × 6 m of new first-floor space (18 m²), that puts an extension over a garage in Sinfin at roughly £31,000–£45,000. 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	£1,580–£2,300 per m²	£28,500–£41,500
Standard	£1,720–£2,500 per m²	£31,000–£45,000
Premium	£2,060–£3,000 per m²	£37,000–£54,000

Planning and building regulations in Sinfin

In England, most garages sit beside the house, so building over one makes a two-storey extension beyond a side wall, which always needs planning permission. If the garage is at the rear, the 3 m and 7 m rules for two-storey rear extensions apply, measured from the original house. A householder application costs £548 (or £575 for applications made from 8 December 2026).

Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

Design points for Sinfin homes

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.

Garage walls and the door opening

Garage walls are often a single skin of brick or block with piers, and the wide door opening needs a beam over it. Many over-garage extensions need new inner walls or a steel frame to carry the floor and to insulate properly, which we confirm before the design is fixed.

How we'd run your project

Start at your house
We come to your home in Sinfin, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Design and approvals
We draw the extension and check it against the rules for England, then apply for planning permission or a certificate of lawfulness, whichever fits.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
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 Sinfin

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

Our guide for the East Midlands, which covers Sinfin, is £1,720–£2,500 per m² including VAT. A typical project with 3 m × 6 m of new first-floor space (18 m²) comes to about £31,000–£45,000. 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 should decide householder applications within 8 weeks of validation), 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.

Who handles building regulations for a project in Sinfin?

We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

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.

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.

Nearby

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

Other extensions in Sinfin

All two-storey extension services in Sinfin · Extensions over a garage across Derbyshire

Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.