Accessory Dwelling Units or ADUs can add so much to an existing property. When considering doing an ADU project in your home, there are many things to think about. One major aspect is whether to convert an existing space in your home, like the garage, or to build a new structure as an ADU on the property.

Conversion versus newly built requires all the facts to make an informed decision, and at Apex ADU Builders, we specialize in both types of ADU construction. Keep reading to find out the difference between the two, the cost for each, as well as the pros and cons of both.

Garage to ADU Conversion

When you think of garages, you typically think of the place where your car resides or all the boxes of things you don’t know where else to store. It can also be a place to house your tools, lawn mower, dog kennel, etc. Nowadays, garages are being utilized for much more than storage space; they’re being converted into ADUs or accessory dwelling units.

The garage to ADU conversion is not uncommon. They’ve been referred to as cottages, carriage houses, mother-in-law suites, and much more. Depending on the type of garage you have, they can be attached to the primary residence or detached. Developers can convert them based on their existing dimensions or add on to them. In fact, ADUs can be built on top of garages if the structure permits.

Why Convert a Garage to an ADU?

Depending on your state’s regulations for ADUs, converting your garage into a unit may be your only option. However, there are many more benefits to converting an existing space, like your garage, into an ADU.

Here are some of the reasons why you should convert your garage into an ADU:

  • You’ll save money on construction since the outer shell of your ADU has already been created.
  • You may already have water and power lines running into your garage, saving on cost and time.
  • It would allow you the ease of access between the primary dwelling and the ADU.
  • It can add to the value of the house with an extra renovated space.
  • You won’t need to use any additional space on the property to add an ADU
  • You may not need to apply for or pay for as many permits to convert your garage to an ADU.
  • It may take less time to finish the ADU project.

How Much Does it Cost to Convert a Garage to an ADU?

Converting a garage into an ADU is the most economical way to have an accessory dwelling unit on your property. Each conversion will look different with the work and time required to complete. Some garages require little work to convert into an ADU and will take less time and money. However, the contractor may run into red flags or problem areas in the process of conversion that will add time and money to your project.

On average, a garage-to-ADU conversion can run anywhere between $80,000 to $150,000. The cost of materials is constantly in flux, so depending on where you live and the materials you have readily available, that cost could reach as high as $240,000 in states like California.

An initial consultation with a contractor should produce a quote for the project. Though this quote will give you a better understanding of the costs associated with the conversion, it is only an estimate. The cost of materials can be higher by the time you’re ready for purchase, or there could be some unforeseen issues that need to be taken care of before moving forward. Either way, leave a good amount of wiggle room for unexpected expenses.

What are the Challenges of Garage to ADU Conversions?

Though it’s generally cheaper to take an existing structure, like a garage, and convert the space rather than starting from scratch, it doesn’t mean there are no potential setbacks to converting. One way to know if it’s worth moving forward is to get an inspection and initial consultation with a contractor. They can point out any red flags and advise you on how to move forward.

Here are four common setbacks in a garage to ADU conversion:

  • Structural Difficulties: If the structure is insufficient to handle the conversion, you could be looking at additional work and cost to fix the existing issues.
  • Energy Difficulties: Not all garages are well insulated. If the walls are too thin, additional layers will need to be added to bring the space up to code.
  • Older Home Challenges: Depending on the year your house and garage were built, you may encounter challenges from materials used that have since been banned, like asbestos. Asbestos removal can range from $1,500- $3,000.
  • Shared Utilities: When the property is inspected to determine the feasibility of converting your garage to an ADU, you may discover that you share a sewer line with your neighbor. If that is the case, upgrading the system would be a substantial added cost.

Newly Constructed ADUs

If converting your garage into an ADU is not the route you want to go and you have space on your property, you may consider a newly constructed ADU. This unit would be completely detached from the primary dwelling, typically in the backyard, with a private entrance. While this avenue may be more expensive, other advantages may out way the cost.

Depending on the size of your lot, adding an ADU can allow you to add value to your home, make passive income, and still have space to enjoy being outside on your property. An existing structure presents unique challenges, like undoing work that wasn’t done properly in the first build. A new structure may present fewer setbacks in its completion.
Why Newly Construct an ADU?
Starting from scratch means that you can be more ambitious with the design of the ADU. The only rules you’ll need to follow are those of the state regarding the size and structure of your newly constructed ADU. There are quite a few added benefits to new construction.

Here are some reasons why you should newly construct your ADU:

  • Keep your space in the garage for your vehicles or storage.
  • It may be easier to resell. Not all potential homebuyers want a converted garage.
  • You’ll have more space to work with since most garages are between 162 to 720 sq. feet.
  • You’ll have more control over the design of the unit.
  • You won’t have to worry about setbacks like asbestos popping up and costing more money.
  • Adds value to the overall property. Sometimes in the hundreds of thousands of dollars.
  • You can maintain your privacy with a separate entrance and all the necessary amenities of a home.
  • You’ll be able to rent out the ADU to a potential tenant more easily.

How Much Does it Cost to Newly Construct an ADU?

While building a new structure can be more costly than converting, the return on the investment is well worth any expense upfront. Whether you convert or newly construct, you will have to pay additional property tax on your residence.

On average, a newly constructed ADU costs between $100,000 to $400,000, depending on where you are located. Like with a conversion, the cost of materials could increase between your initial quote and when you’re ready to purchase. There are also hidden costs to consider related to laying the foundation and ensuring proper utility lines to the unit.

As with a conversion, your developer will provide you with a quote. The quote is simply an estimate that should be taken with a grain of salt. It is recommended that you add an additional $100 to $200 per square foot to your budget, just in case. Should any unexpected expenses arise, you’ll be prepared.
What are the Challenges of Newly Constructed ADUs?
Though there are quite a few benefits to new construction as opposed to converting an existing space, there are also challenges to newly constructing your ADU. Aside from the cost, which often is paid back in full when the property is sold, there are a few more things to consider before deciding on new construction.

Here are three setbacks to newly constructing your ADU:

  • Cost of construction: Unlike a conversion, a newly constructed ADU has certain requirements, like a kitchen and bathroom. You may also have to extend utility lines to reach the ADU.
  • Approval and Permitting: The process of getting approval and the correct permits for new construction on your property can be lengthy and complex. Permits can be costly, with zoning permits ranging from $25 to $4,000 and building permits from $450 to $15,000.
  • Structural Difficulties: New construction means laying a foundation for the ADU, and developers don’t know what they are working with until they begin grading the land. Should any issue arise with the property or utility lines, it could affect the timetable and cost of the project.

Final Thoughts

There are benefits and challenges to converting your garage to an ADU or starting from scratch with a new build. The decision may come down to state rules and regulations and what you can afford. Either direction you go will provide added space for guests or tenants and add value to your overall property. If you’re considering an ADU addition or garage to ADU conversion, contact Apex ADU today, and let’s discuss your goals.