Update 2022: The cost of extensions, conversions and other construction projects have soared during the last 18 months due to rising labour costs, material shortages and other factors. This has been well documented in the media and confirmed by our own research. The garage conversion price guide on this page was updated in 2022 but we urge customers to get a custom quote, which will be far more accurate.

This guide is all about garage conversion costs – what you can expect to pay to convert a garage into a practical, usable living space.

A garage conversion is one of the cheapest ways to give your family extra room.

With the cost of moving house so high, homeowners are still choosing to convert their garages and lofts into habitable spaces.

Garages are rarely used to store cars and more often than not, the available space becomes little more than a junk room for items that could be stored somewhere else, like in a garden shed or loft.

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3 Different Types of Garage Conversion

The cost of a garage conversion will depend on the type and size of the existing garage.

Here are the three most common types of garage:

Integral Garage

This is where the garage is inside the house and is the cheapest type to convert.

Attached Garage

This type of garage is attached to the house, usually by a shared wall. An attached garage will have its own roof and several outer walls that will need reinforcing and/or insulating. If the roof is a “flat roof” you may want to convert it to a pitched tiled roof. These garages are the next most expensive option.

Detached Garage

Detached garages are separate from the main house and are the most expensive to convert. Depending on the structure, you’ll probably need to add an extra wall to each side, insulate it, convert it to a tiled roof if it’s flat and install piping for fresh and waste water. The amount of work involved with detached garage conversions makes them prohibitively expensive. It might be better to knock down the garage and build from scratch.

Planning Permission

Integral and attached garages can usually be converted under “Permitted Development” rules. This means you don’t need to apply for planning permission if the conversion doesn’t increase the overall size (footprint) of the house and doesn’t drastically change its appearance.

There are many exclusions to permitted developments so it’s always a good idea to contact your local planning office before proceeding with any work.

The Planning Portal is also a great resource.

Prices: How Much Does a Garage Conversion Cost?

Integral Garage Conversions

Garage conversion costs vary but for an integrated garage are usually between £800 and £1200 per square metre of floor space.

Any significant remodelling of the existing floor space will push the cost to the upper end of our price guide. Many homeowners choose to knock through into the kitchen and then install a new larger kitchen, this is the most expensive option. The cheapest option is to convert the garage into its own room with a single door, ideally from a hallway.

You can expect the price to increase if you instruct an architect to design your project and create technical drawings.

For a single garage, converted into a room without any significant remodelling of the existing floor space, expect the cost to be around £10,500 – £12,500. Your location will also affect the cost of the project as labour fees in London are higher than in Hull for example.

For integral single garage conversions where remodelling of the existing floor space is needed, perhaps to extend a kitchen or redesign the living room/dining rooms etc, expect the cost to be around £14,000-£17,000.

Attached Garage Conversion Costs

Attached Garages are usually more expensive to convert, the roof may need changing to a tiled roof and there are more walls to potentially strengthen and insulate.

Expect the cost to be between £1150 and £1400 per square metre, excluding architect fees if you choose to use one.

A single garage conversion is likely to cost between £16,000 and £20,000 depending on where you live and the amount of remodelling required.

Detached Garage Conversion Cost

These are by far the most expensive and are more likely to require planning permission.

The cost per square metre will only be slightly less than a newly constructed extension so many homeowners choose to bring down the garage and design a more practical extension.

Expect the cost to be in the region of £1400 – £1600 per square metre.

What Work Is Involved When Converting a Garage?

Here is a list of the work that might need to be completed, every home is different and this list isn’t exhaustive:

• Damp proofing the wall.
• Insulate the wall.
• Insulate the ceiling
• Relocating access drains (inspection chambers) if you have one in the garage.
• Damp proofing, insulating and raising the floor.
• New windows and doors.
• Convert the roof from felted flat to a pitched tiled roof.
• Brickwork around the new windows.
• Wall strengthening.
• Knocking through into the existing home and inserting steel joists to support the walls above.
• Remodelling the kitchen or other living space.
• Flooring, blinds and decorating.
• Wiring, plumbing, heating etc.
• For double garages, you may need to upgrade the boiler if it’s not powerful enough to cope with 2-3 extra radiators being added to the system.
• Building Control notification.
• Planning permission, structural engineer and architect fees if applicable.

Does a Garage Conversion Increase House Value?

If done correctly with good planning, a garage conversion can add up to 10% to the value of a home.

Unfortunately, not every conversion is done to a high standard.

Here are our tips to maximise the value of your home:

• Extending the kitchen and/or adding a kitchen diner is a great idea as the kitchen is a key selling point of any home.
• Try to keep the floors on the same level throughout the home, you don’t want the space to feel different to any other part of the home.
• If the converted garage will be used as a room, perhaps a dining room or study, the room should have a door directly off a hallway. Having to gain access via another room is not a good idea and may put off potential buyers.
• If your garage is used as the only access point to the rear garden, blocking off this access could put off a potential buyer. Not every homeowner wants to go through the house to get into the rear garden.

How Much Do Architects Charge and What About Structural Engineer Fees?

You don’t need to use an architect unless the conversion is complex or involves significant remodelling of the home. If you do instruct an architect to draw up plans, expect their fees to be between 10 -15% of the total build cost.

Structural engineers can provide you (or your builder) with calculations for supporting steel joists that will be needed should you knock through a supporting wall. Their fees vary but for straightforward projects like this expect the cost to be between £275 and £375. For larger projects that involve significant remodelling of the existing floor space and several steel joists, expect to pay up to £500.

This page explains in more detail the differences between architects and structural engineers and also delves into the prices they typically charge.

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This guide to garage conversion costs written by Danny Woodley and was last updated in April 2022.

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