Garage conversions: the ultimate guide to budgeting, planning and designing a garage conversion

Garage conversions are a great solution for anyone who wants more space but doesn't want to add-on. Find out how to successfully convert a garage into extra living space

Garage conversions: by OB Architecture
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(Image credit: Martin Gardner)

Garage conversions are a cost-effective way to add more space. You can add up to 10 percent to the value of your home and gain valuable extra living space that's less prone to planning complications or overspending than putting an addition onto your home. Plus, if you have a two- or three-car garage, you could convert just half the space. Doing so means you will gain living space and continue to benefit from a parking space. 

Garage conversions also mean you won't lose any yard space like you would with an addition. Better still, converting a garage is significantly cheaper than an addition expect to pay anything from $5,000 upwards – and much more affordable than buying a new house

In this three-page guide, we look at how to cost, plan and design your garage conversion for the best possible results.

How much do garage conversions cost?

Garage conversion costs are significantly lower than those associated with an addition 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.

So, how much do garage conversions cost? You can expect to pay between $10,000 and $15,000 depending on your location and the specs of the job; on the low-end if the walls and floor are stable, there is a watertight roof, and the ceiling height is sufficient, on the high end (or even higher) if the space requires significant structural work or live in an expensive major metropolitan area like New York or San Francisco.

Should I convert my garage?

If you can't decide whether to convert a garage or not, consider these pros and cons: 

Profit vs cost: a garage conversion should add more value to your home than it costs to build. But always ask a trusted local real estate agent first. 

Space vs spend: a garage conversion can cost as little as $7,000, way less than you could ever hope to add on for.

Moving costs vs spend: depending on how ambitious your plans are, it will be cheaper to convert a garage than to move for more space.

If the structure is attached to the house, rather than integral, and needs structural repairs, it may be more cost-effective to demolish and replace it.

Compared to the cost of a single story addition, which averages $48,000 according to homeguide.com, it's a cost-effective way to gain more space indoors.

Design costs

Design fees for a garage conversion range from $75-$300 an hour, plus $100-$150 an hour for a structural engineer. 

Dining area with Philip Starck Ghost Chairs in a converted garage

Part of this former garage has been transformed into a dining room that opens on to the outdoor space

(Image credit: ZazuDesigns)

Factors that might affect garage conversion costs

Typically, a garage conversion will cost more if the original structure is unsound. If you are going to spend a lot of money stabilizing the building, knocking the original garage down and building from scratch might be cheaper.

Another factor to consider when costing a garage conversion is the perceived value that it will add to your home. Check the value of houses in your area. If there is little off-road parking, homes with garages might be valued higher than those without. Unless the added space is vital, don’t run the risk of reducing the value of your own home.

A partial garage conversion should cost less, but not by much. Fewer materials will be needed, but services, such as electrics and plumbing, will still have to be installed and budgeted for.

Garage conversion costs: interior fittings

Garage conversion costs need to incorporate the interior fittings, the cost of which really does depend on exactly how you'll be using the room. However, you can use these figures below as a rough guide. If the room is to be just an extra living space, perhaps as a play room, make sure you future-proof the wiring and lighting in case you want to convert it into a TV room in years to come.

  • For putting a kitchen into a garage conversion, budget from around $15,000 to $30,000, depending on the specification; if you go high end, costs can increase significantly.
  • For a bathroom, factor in around $4,500 to $11,000 for the plumbing and fittings.
  • For a mudroom or laundry room, perhaps with a big sink for washing dogs, plan for between $7,000 and $15,000.
  • For flooring, budget in the region of $5 to $15 per square foot depending on the material you choose.
  • Set aside from around $2-3 per square foot for drywall, plus paint.

a conversion of a integral garage

Berry Construction converted an integral garage in London into a valuable double bedroom (which can be seen below) with en suite shower. The project cost around £40,000

(Image credit: Berry Construction)

Garage conversion costs: adding heating and cooling

Heating and cooling costs are another big expense when converting a garage. While in some instances, it is possible to extend your existing HVAC system to the garage, in other cases it might be difficult of next to impossible. Depending on how you set up your room, it could also be against building codes, so be sure to check if you decide to go this route. 

And easier and often more cost-effective way to heat a garage conversion is to install a ductless mini-split system. These systems act as heating and cooling units and are mounted to the wall. The unit itself will cost around $1,000-$1,500, plus the cost of installation. Expect to pay between $1,000 and $2,000 depending on the size of your space and your location. For a quote tailored to your conversion, check out The Home Depot, which offers mini-split installation services that can be quoted and booked through their website.

Garage conversion costs: professional project fees

Garage conversion costs may also include professional fees, such as those from an architect, engineer or designer. For an architect, planning drawings and construction drawings could each come in around $2,000 upwards. You may also need a structural engineer to size roof joists and foundations, particularly if you are building on top of the garage, too. Factor in $500 to $1,000.

Dining room in a garage conversion

This open plan kitchen diner was once a garage beneath a pretty coach house in Devon.

Garage conversion costs: permitting and inspection fees

In most locations, you'll need to get permits before you start your garage conversion, and inspections when construction is complete to ensure the space is up to code. You'll also likely need a certificate of occupancy once the work is complete for it to be considered legal. Don't skip this step since non-permitted structures can't be counted in the resale value of your home. It'll cost you about $1,000 - $1,500 to obtain permits and inspections, but it's a necessary expense.

Note: some cities don't allow, or enforce special regulations around, garage conversion

  • Most cities allow garage conversions, but not all do. In Azusa, Calif., for example, it's illegal to convert a garage into living space. Researching permitting in your area will tip you off as to whether or not it's allowed where you live.
  • In San Diego, you may be required to move or close off your driveway after you convert your garage. The city doesn't allow driveways that don't lead to legal off-street parking.
  • Some jurisdictions require there be covered on-site parking for local residences, so you'll need to plan for an alternative parking situation.

Planning a garage conversion >>