Garage conversions are one of the quickest and most cost-effective ways to add living space to your home

So, where’s the car?

While many homes have garages, few people park a car inside. Most of us are happy to leave our cars sat on the driveway or street – while we fill our garages with everything from bikes to lawn movers and half-empty tins of paint. In older properties and even some brand-new ones, the garage may be too narrow to store an average-sized family car. Other garages are just too cluttered. Whether it’s single, double, integrated or detached, a garage has the potential to add living space and value to your home. But before you sacrifice your garage, think through the implications for your family and future buyers. In some areas where parking is at a premium, it might be better to extend or convert the loft.

Aquila Property Group garage conversion with mezzanine level bedroom space

Better uses

A single garage will provide about 15m2 of potential living space; more than enough for a home office, playroom, extra bedroom or accessible downstairs bathroom and toilet. A double garage, or a single garage plus car port, at around 30m2 gives you more options. It could house a big family room with guest bed and bathroom or annex for ‘boomerang’ children, elderly parents or a paying lodger. 

If it’s an integrated garage, you could knock down the interior wall to join up with the existing house, perhaps extending the kitchen or hallway. If it’s a detached garage, it might be better suited to a more separate use such as a home office or guest annexe.  Alternatively, you might keep a single parking space by erecting a suitably insulated partition and fit out the rest for a utility room or mini-gym. Carefully consider how you want to use the space and what your budget will allow.

Getting the design right

.It’s important to consider what type of internal space you will be left with if you simply replace the garage door with a new brick wall and windows. It may create a dark, narrow room with a low ceiling which can feel quite claustrophobic. Consider adding a feature glass block wall to brighten the space or floor-to-ceiling windows facing the back garden if your budget stretches that far. Or you could potentially raise the roof to create a higher, vaulted ceiling. “If you have a flat roof on a single-storey garage, it might be worth stripping it and replacing it with a new pitched roof, said architect Mark Benzie of C3 Design.  “Instead of a pokey room with a low ceiling, you have a vaulted space up to 3.5 metres high, which is allowed under permitted development, and you can add roof windows to increase light.”

For bigger projects, working with an architect can help you maximise the potential of your garage and transform it into an attractive living space that blends seamlessly with your house.

Do I have to apply for planning permission?

Consult your architect and/or local planning authority on whether permission is required as the rules are quite complex. Typically, if the garage conversion involves mostly internal work, such as knocking through from an integral garage to the kitchen, it may be considered a permitted development. This means it doesn’t need formal planning consent. However, in some areas permitted development rights for garage conversions have been removed, so it’s always best to check. If you want to significantly alter the external appearance, such as swapping the big garage door for a new exterior wall and windows or adding an extension, a full application will be necessary.

Building regulations

Even if you don’t need planning permission, you’ll still need building regulations consent and sign-off to convert a garage into a habitable space. “Garages are not designed to be lived in, so the structure will need upgrading. Insulation is the main issue along with damp-proofing, ventilation, and how you deal with structural issues like single-skin brickwork and foundations which may need strengthening,” said architect Scot Masker of Pro Vision.

An experienced builder or your architect can advise if you need to submit a building notice or a full-plans building regulation application to your local planning authority.  Work can then start, and a building inspector will then visit the site to check the work as it progresses. In addition to structural safety, they will look at insulation, energy-efficiency, fire-safety, damp proofing, ventilation, electrics and plumbing. Once the building inspector is satisfied, a completion certificate will be issued.

Building works

There are all sorts of garage design issues that need to be tackled. “Garages are supposed to have a lower floor than that of the house, so you will have to think about raising the floor slab,” said Masker. The existing concrete floor may need to be levelled and damp-proofed. Electricity and gas metres are often housed in garages. “If they need to be moved, that will cost £1,000 each,” said Benzie.

You may also need to pay a structural engineer to assess roof joists and foundations, especially if you are planning to build on top of the garage. Other key works may include upgrading the walls if they are not built to the same standard as the house, for example, erecting stud walling inside existing single-skin brickwork to create a cavity wall stuffed with insulation.  The main garage door will typically be infilled with brick walling to match the rest of the building. New windows and doors will have to comply with the required U-values to ensure energy efficiency.

Heating and electrics

Perhaps the trickiest part is to add heating. You may need new electrical circuits and heating loops, which will put additional loads on your consumer unit and boiler which may need updating. Heating-wise, wall-mounted electric radiators are possibly the cheapest solution as they don’t require new pipework. Alternatively, slimline underfloor heating can keep the room warm and maximise free wall space. Energy-efficient LED downlights are a good choice, especially if ceiling height is limited. The most straightforward way to get heating and electrics in place is to hire professionals qualified to self-certify their work under Part P of the Building Regulations.

Garage conversion costs

If the structure is reasonably sound, a garage conversion should be cheaper than building a new extension. An integrated garage could be converted for as little as £400 per m2 or £6,000 for a 15m2 garage.  Ultimately, the cost will depend on the scale of building work and quality of finish. “It’s possible to spend as little as £6,000 to get a cheap extra room but if you put on a new roof and make other changes it can cost £12,000-plus,” said Benzie.  

Will it add value?  Paul Preen of Lang, Town and Country estate agents, said a garage conversion can add between 5% and 10%, but adds a note of caution. “If you convert the garage you will lose some value, but you can compensate for it by putting in decent storage, such as a big garden shed.

“Nine times out of ten, people don’t use garages nowadays to park a car inside; it’s just used for storage. But you do need to think about how you will use the new living space and how it will flow with the rest of the house. Just bricking up the garage door is a waste of time.”