Garage conversions and extensions

If you’re not using your garage to store a car, why not get the most of it and create a new room? 

Given as the foundations are already there, it’s often a much cheaper way to create more space. 

Plus, garage conversions mean you won't lose any garden space like you would with a standard extension. 

Plus, once it's a functioning room, it's less likely than a garage to get turned into a storage room that gets increasingly filled with stuff.

Before you begin

First consult an estate agent about whether converting your garage could have a negative impact on your property's value. If you'll be living in your home for years to come, it may well be worth going ahead anyway, whatever they say, but if garages are highly sought after in your area, think carefully before converting yours. 

Before you start work on the conversion, consider what you’ll do with everything currently kept in the garage. If you store a lot of garden gear and bikes in it, you may need to factor a shed into your plans; if it’s where you keep your large spare freezer, you’ll need to work out where it can be moved to – or whether you can live without it.

If you really have no room anywhere else for these things, perhaps a partial garage conversion (or a conversion that has lots of storage space set aside within it) will work better for you.

Attached vs detached garages

A garage conversion is one of the speediest and most affordable routes to adding extra space to your home. Plus, you won't need to move out while works are happening. If it’s integrated or attached, the garage should be fairly easy to work into the main house. 

If your garage is detached from the main property, you might need to apply for planning permission. In fact, in some circumstances it may be better to create a separate building that links back to the original structure, perhaps via a glazed corridor. This kind of approach can work especially well for heritage homes, where the planners may be keen on the idea of creating a distinct new zone that’s subservient to the main house. A detached structure lends itself to segregated uses, such as an annex or quiet home office.

Do you need Planning Permission for a garage conversion?

With many garage conversions – particularly attached and integral spaces – most of the work is internal (with the exception of changing the frontage and adding a window or two). This is likely to be considered permitted development, so it won’t usually need formal planning consent. But do check with your local authority before you begin.

However, if you live in a conservation area or listed building, you will almost certainly need planning permission and potentially also listed building consent. 

It is also worth checking for any planning conditions attached to the house or garage when constructed (for example, the garage has to remain as parking) before beginning works as an application will need to be submitted to remove the conditions.

If your intention is to convert a garage into a separate house (regardless of who will occupy it), then planning permission may be required no matter what work is involved. Discuss such proposals with your local planning authority to ensure that any work you do is lawful and has the correct permissions.

How much does a garage conversion cost?

Garage conversion costs are significantly lower than those associated with an extension because you will save money on laying new foundations and building new walls.

Your garage may also have power and perhaps even plumbing already, both of which will reduce your garage conversion’s cost even more. 

Head to our extensions costs page to unlock RICS data on a single and double storey extension. 

If you're not yet a member, join Which? here.

What insurance do you need if converting a garage?

As with any type of extension, conversion insurance will cover the work being carried out and the existing structure. It should also cover materials, plant tools and equipment.

This type of insurance should also cover public liability and employer's liability – should any of the workers be injured on site, for example. Public liability and employers liability is automatically included to ensure you are adequately protected, but do just double check to make sure it's definitely included. 

Ensure that the conversion insurance is ready to go from the moment work starts until the very end of the job.

Conversion insurance needs to be in place from the moment you plan to start works on the property and should continue to the point the project is completed and taken into full use.

Who designs and builds a garage conversion?

You can either design and oversee the project yourself and employ builders, or you can hire an architectural designer or a specialist garage design and build contractor, who will help put your ideas into fully formed plans, and give you expert design input. The latter will of course be more pricey.

If the garage is attached or integral to your home, they will also help you consider the best position for access and put plans in place to redirect this if required.

With more complex projects, you may prefer to have full structural plans drafted. This gives you peace of mind that building control has inspected the drawings and confirmed that – if it’s constructed as per the approved plans – your conversion will conform to regulations.

In addition to structural safety, key areas your building control officer or approved inspector will look at are damp proofing, ventilation, insulation and energy efficiency, fire safety (including escape routes), electrics and plumbing.

To find an architect or architectural technologist, visit RIBA or CIAT.

Specialist garage conversion companies can save you time in putting together applications and will be experienced in getting the best from this type of project, but any good builder will be able to do the job. Ideally, work with someone who has been recommended and is a member of an accredited body, such as The Federation of Master Builders. Head to Which? Trusted Traders for someone local to you.

Replacing the garage door

The garage door will have to be replaced with a new wall and/or window. This may mean new foundations, but there are other options, including having lintels set just below ground level that bear on sound masonry or existing foundations each end. 

If you live in a conservation area you might find that your local council will want you to retain the original door. Architects can often incorporate them stylishly into the new design.

If you're after advice from an architect before kicking off a project, head to our advice from a builder and architect page for their top tips.