Extensions over a garage in Chaddesden

Before you start in Chaddesden, here's what applies.

Postcode districts: DE21
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: Oakwood (Derbyshire) (1 mile), Derby (1.8 miles), Sinfin (4 miles)
Distance to Derby: about 1.8 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 district DE21 in and around Chaddesden, along with neighbouring Oakwood (Derbyshire), Derby and Sinfin.

What it costs in Chaddesden

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 Chaddesden at roughly £31,000–£45,000. We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.

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 Chaddesden

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 Chaddesden homes

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.

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

Understand the brief
At your home in Chaddesden we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Engineer it
Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Questions about extensions over a garage in Chaddesden

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

Our guide for the East Midlands, which covers Chaddesden, 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.

Which postcodes do you cover around Chaddesden?

We cover Chaddesden (DE21) and nearby places including Oakwood (Derbyshire), Derby and Sinfin, plus the rest of Derbyshire. 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 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.

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.

Nearby

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

Other extensions in Chaddesden

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

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