Garage conversions: costs, rules and planning

Updated 26 October 2026 · SK Home Improvements

What is a garage conversion?

A garage conversion turns an existing garage into a warm, habitable room that is part of the house. The garage door is usually replaced with a wall and window, the floor is raised and insulated, the walls and roof are insulated, and heating, lighting and sockets are added. Integral and attached garages are the most common conversions, because they already share a wall with the house.

Detached garages can be converted too, but they need more work to bring services across, and using one as a separate annexe or home has wider planning implications.

Is your garage suitable for conversion?

Most attached and integral garages can be converted, but a survey checks a few things first:

• Foundations: the new wall under the old garage door opening needs adequate support, and the existing foundations there may be shallow.
• Walls: garage walls are often single-skin brick or block, which needs insulating and damp-proofing.
• Floor: garage floors are usually lower than the house and may lack a damp-proof membrane.
• Roof: a flat garage roof may need replacing, and any roof needs insulation.
• Services: a boiler, meters or a soil pipe in the garage may need moving or boxing in.

Head height is rarely a problem in a garage, but a sloping drive or a steep step down from the house may be.

How much does a garage conversion cost?

A single garage conversion typically costs £12,000–£28,000 including VAT, depending on the size, the condition of the structure and what the new room is for. A simple home office or playroom sits towards the lower end. A double garage, a shower room or utility with new plumbing and drainage, a replacement flat roof, underfloor heating or bifold doors to the garden push the price up.

Fees for drawings and building control are often extra, and planning fees apply if an application is needed. Our guide-price tool gives a range based on your answers.

Do you need planning permission for a garage conversion?

Many garage conversions do not need planning permission, because the work is mostly internal and replacing the garage door with a wall and window is often permitted development where the materials match. But permission is commonly needed where:

• A planning condition removes permitted development rights or requires the garage to be kept for parking, which is common on newer estates.
• The house is listed, or in a conservation area where the change to the front would need consent.
• The conversion enlarges the building or changes its outside significantly.
• A detached garage is to become a separate home or a self-contained annexe.

Check your title deeds as well, because covenants can restrict conversions separately from planning. The rules differ across England, Wales, Scotland and Northern Ireland; see our planning permission guide.

What Building Regulations apply to a garage conversion?

A garage conversion almost always needs Building Regulations approval, or a building warrant in Scotland, because it turns a garage into a habitable room. Building control usually checks:

• Foundations and damp-proofing for the new wall in the door opening.
• A floor with a damp-proof membrane and insulation, often raised to the level of the house.
• Insulation to walls and roof to current energy standards.
• Ventilation, including background ventilation and, for a shower room or utility, mechanical extraction.
• Fire safety, including smoke alarms and, in some layouts, an escape window or protected route.
• Electrical work, installed and certified by a suitably qualified electrician.

Our Building Regulations guide explains the approval process in each nation.

Can you convert only part of a garage?

Yes. A part conversion turns the back of the garage into a room, such as a utility, home office or shower room, and keeps the front as storage, usually behind the existing garage door. It costs less than a full conversion and keeps the garage looking unchanged from the street, which can help where planning rules or covenants protect the front of the house.

The new room still needs Building Regulations approval, with an insulated partition wall between the room and the storage area, plus insulation, ventilation and fire separation. A part conversion will usually leave the space too short to park a car, so think about parking and storage in the same way as for a full conversion.

How long does a garage conversion take?

A single garage conversion typically takes two to four weeks on site, and a double garage or a conversion with a shower room can take longer. Most of the work happens inside the garage, so disruption to the rest of the house is limited until the new room is connected to it, usually in the final days. Allow time beforehand for drawings, building control approval and any planning application.

What happens to parking and storage?

Converting a garage removes a parking space and a lot of storage, so plan for both before you start. Check that your driveway can still take the cars you need, as on-street parking pressure and council parking standards can matter, especially where a planning condition applies. Many people keep a small storage area at the front of the old garage, add a garden store, or build storage into the new room.

In some areas, buyers value a garage, while in others an extra room adds more appeal. It is worth weighing how you will use the space against what your local market expects.

How do you plan the new room?

Start with how you will use the room, because that decides where windows, sockets, radiators and any plumbing go. A home office needs good light, data and plenty of sockets; a bedroom needs an escape-friendly window and a quiet position; a utility or shower room needs drainage and extraction. Think about the step down from the house, heating from the existing system or a separate electric source, and the flooring.

We survey the garage, check approvals and give a written quote. See our garage conversions page for more detail.

Related services

• Garage conversions: guide £12,000–£28,000 inc VAT
• Replacement windows: guide £4,500–£9,000 inc VAT
• Flooring: guide £1,200–£4,000 inc VAT

Figures in this guide are typical UK ranges including VAT where it applies. They are not quotes. Rules on planning and building control differ between England, Wales, Scotland and Northern Ireland and change over time, so we check what applies to your property before quoting.