Extensions over a garage in Gloucestershire

Gloucestershire at a glance

Nation: England
Price region: South West England
Postcode areas: BS, GL
Towns covered: 15 listed below, plus surrounding villages
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
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.

The main places we list in Gloucestershire are Gloucester (GL1), Cheltenham (GL50), Stroud (GL5), Kingswood (BS15), Mangotsfield (BS16) and Yate (BS37). We cover the villages in between too.

Guide price in South West England

Our guide for South West England is £1,800–£2,630 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 Gloucestershire at roughly £32,500–£47,500. Kitchens, bathroom fittings and flooring are priced separately so you can compare like with like.

Spec	Per m²	Typical project
Essential	£1,660–£2,420 per m²	£30,000–£43,500
Standard	£1,800–£2,630 per m²	£32,500–£47,500
Premium	£2,160–£3,150 per m²	£39,000–£56,500

Rules in England

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.

The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.

Getting the design right

Fire separation

If the garage stays a garage, the floor between it and the room above, and any door into the house, must give fire separation under building regulations. That usually means fire-resisting plasterboard ceilings, sealed gaps and a fire door, which we design in from the start.

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 work in Gloucestershire

Visit and first ideas
One of our team visits your house in Gloucestershire, checks the walls, roof and drains, and sketches out options with you.
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.
Engineer it
Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.
Build and hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.

Towns we cover in Gloucestershire

Extensions over a garage in Gloucestershire: questions

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

In South West England our guide is £1,800–£2,630 per m² including VAT, so about £32,500–£47,500 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.

Can I add an en-suite above the garage?

Yes, and it is a common choice for a main bedroom. The en-suite needs an extract fan under Part F, a route for the soil pipe down to the drains and enough fall for the waste, which can be harder over a garage. We plan the pipe route through the garage or an outside wall early.

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.

Will I need planning permission in Gloucestershire?

Gloucestershire is in England. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.

Neighbouring areas

All extension services in Gloucestershire · About extensions over a garage