Over-Garage Extensions: Cost, Planning and What to Expect in Berkshire

A Smarter Way to Add Space

If you have a detached or integral garage, you may already be sitting on the footprint for an extra room. An extension above the garage is one of the most cost-effective ways to add a bedroom, bathroom or home office — without sacrificing garden space or altering the ground floor layout.

We build over-garage extensions across Berkshire, from Reading and Wokingham to Bracknell, Windsor and Newbury. Here is what you need to know before you start.

What Is an Over-Garage Extension?

An over-garage extension adds a storey above an existing garage structure. Depending on your property, this might mean:

• Adding a room above an integral garage (one that is part of the main house)

• Extending above a detached garage in the garden

• Creating a link between the garage roof and the main first floor

The most common use is a new bedroom or ensuite, but we have also built home offices, playrooms and utility spaces this way.

Do You Need Planning Permission?

This depends on the type of garage and the scale of the build. As a general guide:

•      Extensions above an integral garage often fall under Permitted Development (PD), meaning no planning application is needed — provided the work stays within certain size limits and does not alter the roofline significantly.

•      Works above a detached garage are more likely to require full planning permission, particularly if the result looks like a separate dwelling.

•      Properties in Conservation Areas or those with Article 4 Directions have stricter rules and PD rights are often removed.

We carry out a planning assessment at the start of every project and handle any applications directly with the local authority. You will not need to deal with the council yourself.

How Much Does an Over-Garage Extension Cost?

Costs vary depending on the size of the garage, the structural work required and the specification of the finished room. As a rough guide for Berkshire in 2026:

•      Basic over-garage extension (new room, standard finishes): from £40,000

•      Over-garage extension with ensuite: from £55,000

•      Larger or more complex builds: £70,000 and above

The biggest cost variable is the garage structure itself. Older garages often have foundations and walls that were never designed to carry an upper floor, which means additional structural work before the extension can go up. We assess this during the initial survey and price it transparently before any work begins.

Our over-garage extensions start from around £1,600 per m2 for the build, with design, planning and structural engineering included in our full service.

What Does the Build Process Look Like?

A typical over-garage extension follows these stages:

•      Initial survey and structural assessment of the existing garage

•      Design and planning — architectural drawings, structural engineer sign-off, planning application if required

•      Foundation and structural upgrades to the garage where needed

•      Superstructure — walls, roof structure, insulation and weatherproofing

•      First fix — electrics, plumbing rough-in

•      Internal finish — plasterboard, flooring, joinery, decoration

Build time is typically 10 to 16 weeks from groundworks to handover, depending on the scope. Projects requiring planning permission add 8 to 12 weeks to the overall programme before the build begins.

Is an Over-Garage Extension Worth It?

For most Berkshire homeowners, yes. You are adding usable floor space without touching the garden and typically without needing to move out during the build. Estate agents in the area consistently report that an additional bedroom adds significant value — often well above the build cost in the current market.

If your garage is sitting largely unused but your home feels cramped, an over-garage extension is worth serious consideration before you think about moving.

Talk to Us About Your Project

We have been building extensions across Berkshire for over 20 years. If you are thinking about building above your garage, we are happy to take a look and give you an honest assessment of what is possible and what it will cost.

Get in touch at hello@nuovahomeimprovements.com or call 07355 894804.