How Much Does It Cost to Build a Garage Apartment? [2025 Data]

A garage apartment can be a great way to create a living space for aging parents, children who have recently graduated from college, or extended family. It can also be a great way to start making rental income without actually buying a second property. While the cost to build an apartment above a garage ranges from $50,000 and $270,000, the choices you make play big roles in determining the final price. This guide covers what you can expect when adding a garage apartment to your property.

Building a Garage With an Apartment Cost Factors

Like any new construction project, the cost to build a garage with an apartment can vary based on the design choices you make. Here's a rundown of the main cost factors that will determine your final investment.

Size

With the average garage costing $52 per square foot to build, you'll see your investment for this project changing based on how large you want your new garage to be. Here's a rundown of some common layouts:

• 12 x 24 single-car garage: $15,000

• 14 x 28 single-car garage: $20,000

• 24 x 24 two-car garage: $30,000

• 24 x 20 two-car garage: $32,000

• 26 x 24 three-car garage: $45,000

• 30 x 40 three-car garage: $63,000

When adding a finished room above the garage, the cost to get that space completed averages around $300 per square foot.

Materials

When building a garage with an apartment, you'll need to utilize all of the same building materials that go into any home construction. Here's a look at what you can expect to pay per square foot.

Framing

The framing cost for a garage with an apartment is between $5 and $13 per square foot. The height of the new structure is one of the biggest factors here because framing two-story or three-story structures can be significantly more expensive compared to framing single-story structures.

Foundation

The cost to put down a concrete slab that will serve as the foundation for your new garage is between $4 and $8 per square foot.

Roofing

Putting a new roof over your garage with an apartment will cost anywhere from $2 to $10 per square foot.

Plumbing

While an ordinary garage won't require plumbing, adding a garage with an apartment puts you on the hook for adding rough-in plumbing. This can cost anywhere from $4,000 to $8,000.

Gutters

Gutter installation costs between $4 and $30 per linear foot.

Wiring

Wiring up a new home can cost between $5 and $10 per square foot. However, the cost of running wire from the street to a new construction alone can cost around $12,000.

Type of Garage Door

A new garage door is one of the largest single purchases associated with building a new garage. The average cost for a new garage door is between $748 and $1,642.

Location

When it comes to hiring professionals, sourcing materials, and other costs associated with building a new garage with an apartment, local rates will dictate how much you pay in the end.

Permits

This is one project where you can be pretty certain that you'll need to pull permits before you can begin work. With residential garage permits starting at around $74 in most places, set aside a few hundred dollars for the various permits that may be needed for all of the different elements that go into building a new structure.

Labor

In many cases, labor can account for 30% to 70% of a project's total cost. The average cost for labor when building a garage is $20 to $49 per square foot.

Additional Costs to Consider

Here's a look at some extra costs that often go along with building a new garage.

HVAC

A new HVAC system can cost between $5,000 and $13,000. However, you'll probably be on the lower end if your apartment is much smaller than a standard home. Expect to pay $15 per linear foot when extending ductwork throughout your new garage apartment.  

Maintenance

Don't forget about the long-term cost of maintaining a new apartment! While caring for the new addition should be relatively inexpensive for the first few years, you will eventually need to manage new roofing, siding, and other details. Try to put away a certain amount every month as part of a maintenance fund to ensure that the money is there when you need it.

Legal

If you're building a new garage apartment as an investment property, make sure you have a business account for handling legal fees. While there's no way to anticipate any legal costs associated with being a landlord, you should consider putting away a certain percentage of monthly rental income toward a legal fund.

Insurance

You'll most certainly need to update your homeowner insurance after adding a new garage apartment. If the apartment is simply additional living space, talk to your agent about updating your policy to include the extra space. If you're using the property for income, you'll need to pay for landlord insurance that protects you financially from damage or injuries related to the property.

Why You Should Hire a Garage Building Pro

Building a garage apartment is a major construction project involving structural framing, foundation work, wiring, plumbing, and roofing, in addition to proper permitting and code compliance. All that considered, this isn't a project that a DIYer can handle on their own.

Hiring a local garage building contractor ensures the new structure is safe, habitable, and compliant with all local requirements. 

Here’s why it’s ideal to hire a garage building pro

Because a garage apartment involves full-scale construction, here’s why hiring a pro is your best option:

• Pros handle framing, foundation, roofing, wiring, plumbing, and ductwork—tasks that require advanced specialized trades and building knowledge.

• Professional garage builders ensure the apartment meets building codes and safety standards, and all required permits.

• Running utilities like wiring and plumbing incorrectly can lead to dangerous or costly mistakes.

• A professionally built structure reduces liability and helps the apartment add value rather than become a stress-filled money pit.

If you want to DIY part of building a garage apartment

While this is not a DIY-friendly project, homeowners can help with small, non-structural tasks:

• Manage finish-level jobs such as painting, trim touch-ups, or simple cosmetic updates

• Move belongings or clear the workspace before construction begins

• Shop independently for budget friendly doors, windows, and other finishing touches.