Photo of a gray garage door on a cream colored house next to a green hedge with the caption "Garage ADU Pros & Cons"

Accessory dwelling units (or ADUs) are all the rage, especially because an ADU provides additional housing without the need to buy more land. You’re contemplating adding a garage ADU to your home, as your garage is certainly spacious enough. Is this the best idea?

Garage ADUs can provide a generous amount of living space to a renter without the need for them to come into the main dwelling unit (your house). However, restrictions on where you can build an ADU and the need for a permit in some cities and towns can make your building goals difficult.

This post will be your guide to the garage ADU. We’ll explain the types of dwelling units you can build and then delve deep into the pros and cons. By the time you’re done reading, you’ll know whether it’s feasible to add a garage ADU to your property.

What Is A Garage ADU?

If you’re thinking about building (and financing) an ADU, before you can get even a single blueprint designed, you must plan the type of ADU you want. The most common options are ADUs in the basement or garage.

Garage ADUs include two types, above-garage and garage conversion ADUs.

Above-Garage ADU Addition

An above-garage ADU is a new construction, as the dwelling unit would be built over your existing garage. These ADUs are sized to be roughly as large as the garage, but can protrude over the garage depending on your design preferences.

An above-garage ADU is cozy and intimate. It might not be the type of place that someone lives in permanently, but for welcoming the in-laws, the adult children, or out-of-town friends, an above-garage ADU is perfect.

the inside of a small above garage adu apartment, with white walls, a short cathedral ceiling, showing a bed against the wall and a brown leather couch
I just stayed in this AirBnB above-garage ADU during my last trip to Denver for a wedding. Even though small, they make great short-term rentals or extra guest rooms! The owner did a particularly great job with the design and use of space in this one given the small ceiling height restrictions.

Converting the Garage Itself to an ADU

The second type of garage ADU is a garage conversion. As the name implies, with this type of ADU, you’d gut your garage of everything in there and redesign it into a living space.

Since many garages feature unfinished walls and unappealing concrete floors and might not be insulated, you’d have to budget for this work as part of the garage makeover.

Compared to an above-garage ADU, though, garage conversions do offer some perks. For one, a garage conversion usually has more living space. Rather than only being a place for your visitors to crash, someone could conceivably live in a garage conversion ADU full-time.

Kristen Dirksen’s YouTube channel has some great videos, but this one in particular features an awesome garage conversion in San Diego, CA.

Flooring resource Better Life Technology states that the average size of a one-car garage is between 162 and 384 square feet. Technically, that would be a junior accessory dwelling unit or JADU, as JADUs are 500 square feet or under.

The second reason to consider a garage conversion ADU is that there’s no need for new construction. That in itself could be a deciding factor.

Garage ADU Pros

Whether it’s a garage conversion or an above-garage ADU, there are a lot of good reasons to consider adding an ADU to your property. This section will outline the benefits of a garage ADU to give you some more information.

Relieves Housing Shortages

America is embroiled in a housing shortage, which is something we discussed here. ADUs, including garage ADUs, are a solution. As we mentioned in the intro, an ADU provides more housing options but doesn’t hog up precious land to do so.

This can preserve more natural resources or allow land to be used for other purposes.

Provides Affordable Housing

ADUs can be more affordable for people to live in compared to a house or a condo. Affordable housing is another ongoing problem that further complicates America’s housing shortage. An ADU kills two birds with one stone.

Cozy & Quiet

Another benefit of garage ADUs is they’re usually quiet. Insulating the ADU will lessen the noise an above-garage ADU resident will hear when someone in the main dwelling unit uses the garage below them.

The coziness of garage ADUs is a definite plus. Small living spaces are quite trendy today, from teeny-tiny homes to converted buses or campers that people live in permanently. A garage ADU nails the coziness factor, allowing you to simplify your life and appreciate more of the little things.

Photo of an aqua-blue detached garage next to a house of the same color. A good candidate for a garage ADU.
Attached and detached garages are both good candidates for a conversion to an ADU. Photo by Sean Foster on Unsplash

Green Space

For those who would otherwise have to opt for renting a traditional apartment, they will be able to enjoy the private yard of the main residence.


Some people assume that building an ADU will be like inviting a new roommate into their home. That doesn’t have to be the case at all. ADUs are standalone homes that feature day-to-day necessities, from kitchen nooks to a bathroom and a bedroom.

No New Construction

This goes back to the point we made before about garage conversion ADUs. You wouldn’t have to get anything added (aside from things like plumbing, electrical, sewer, etc) on to your home with one of these ADUs. You’re only converting the space that’s already on your property into living quarters.

Your yard probably won’t become a construction site for an unknown amount of time. You’ll save money as well (although that money might very well go towards remodeling the garage). Plus, since it’s not new construction, you shouldn’t have to concern yourself with pesky permits and ADU laws.

Garage ADU Cons

Garage ADUs are a wonderful thing, but they’re not without their downsides. Before you start scheduling plans to get a garage ADU built, you’re going to want to carefully read over this list of downsides. Weigh it against the pros section above.

Small Living Area

For as many people who love cozy living spaces, there are just as many who could not imagine living in such a cramped environment. ADUs are not a good fit for these types, and that goes for ADUs in the garage and elsewhere.

Photo of a tiny house/garage ADU type kitchen with modern decor and built-in dining table.
One person’s “cozy” could be another person’s “cramped.”

No More Garage Storage

What did you use your garage for previously? Maybe you parked your car there or perhaps you used the space for woodworking, metalworking, or another hobby. You might have played drums in there or kept off-season items in the garage.

Those days are over. You’ll have to rent a storage unit if you want to keep your stored items. Your car will have to go in the driveway. Your hobbies will have to be moved indoors.

Even if you have an above-garage ADU, you can’t use your garage in the same way. Insulating the walls will prohibit sound, as we said, but insulation can’t block out all noise. Unless you soundproof the ADU, then anytime you’re in there running the power saw or playing drums, the person living in the ADU will be able to hear it.

Laws & Permits

By far one of the biggest downsides to building any type of ADU is the rules surrounding them. (We discussed those rules in a recent post, which you can read here.)

Although the parameters of that article were about building an ADU in the yard, the article also talked about adding an ADU elsewhere on your property, which would be the case for a garage ADU.

In many states across the country, ADUs are allowable, but you must follow certain rules and laws. You might be limited on the size and placement of the ADU per development standards. Before building an ADU, you could be required to obtain permits.  

Zoning laws can also restrict the size of your ADU as well as the number of ADUs on your property. Homeowner’s associations might also have their say about your ADU.

If that sounds like a lot of rules to follow, that’s because it is. To make matters even more confusing, the rules vary not only by state but by the city or town in that state. In some cities, you might be able to build an ADU with fewer rules than in others.

Cost to Build an ADU

With building costs skyrocketing everywhere, ADU’s can’t escape the problem either. And actually, because you’re needing literally everything that goes into a regular home, but in a small package, the cost per square foot is driven up more than a bigger home.

The cost totally depends on your location, current markets for materials and labor, and your ability to negotiate and find good contractors that will be reasonable.

At least around here in the Tampa Bay market right now, ADU’s are costing about $150-175 per square foot if built brand new. Since garages already have things like a concrete foundation and walls that you can use (usually), the cost should be a bit lower, but it’ll still add up quick!

How Much Does A Garage ADU Cost?

Another major deterrent to those considering an ADU is the price. In the post we linked you to in the last section, we quoted the price of an average ADU at between $30,000 and $300,000. Those estimates would likely be what you’d spend for an above-garage ADU.

According to ADU Geeks, per square foot, you’d pay $190 to $215 to convert a garage into an ADU. If your garage is 400 square feet, the project price would be between $76,000 and $86,000. They’re based in San Diego, so your costs might be different in another part of the country.

Don’t forget to factor in insulation, carpeting, new lighting, furniture, or other details you might want to add.

Should You Build A Garage ADU?

So, is a garage ADU right for you or should you refrain for the time being? That’s a choice only you can make, but we can help by reiterating some points.

ADUs, although they do require an initial expense, can earn you back the money. If you charge rent for your ADU, Napa Sonoma ADU states that the rental income is taxable, but construction depreciation costs and maintenance expenses are tax-deductible.

Having an ADU can also increase your property tax rates. If you’re receiving rent for your ADU, this might not be such a big deal. Then again, it depends very much on what you’re paying in property taxes.

ADUs can reduce the current housing crisis that’s rampant throughout the U.S. You also create a source of affordable housing.

A garage ADU lets you enjoy the closeness of having family or friends living nearby without them sharing a home with you. They shouldn’t have to come into your home, nor should you have to enter theirs. The time you spend together would be completely voluntary to maintain a harmonious relationship.

Should you decide to someday sell your home and it has a garage ADU, you could increase the asking price thanks to the addition.


A garage accessory dwelling unit or ADU is a living area within the garage or built over the garage itself. We hope the information in this guide made your decision easier about whether to add a garage ADU to your property!

Leave a Reply

Your email address will not be published. Required fields are marked *