Garage to ADU Conversion: 16 Questions and Steps to Consider

Garage to ADU Conversions feature image - GMJ Construction

Garage to ADU conversions provide extra living space for the homeowners. ADUs are separate, independent, standalone living units that are legally rentable. The ADU (Additional Dwelling Unit) is a separate tiny house, making the lifestyle simple and nomadic. If you have an unused garage, converting it to an ADU would be wiser.

Before getting started with an ADU conversion, you should consider the following steps and get answers to the below questions. If you want your conversion to be done seamlessly on time, then hiring a good contractor will make much of your job easier. Timely permit clearance and practical cost analysis will allow you to construct your dream ADU. Below are some must-know steps to consider, along with informational FAQs regarding a garage to ADU conversion. With no further ado, let’s get started.


1. Upgradations Done for Converting a Garage to an ADU?

Upgradations needed for Garage to an ADU - GMJ

Even if your garage is in brand-new condition, built just a year ago, you will still do a couple of upgrades to start the garage to ADU conversion. It would also be helpful because, in some communities, residential building codes are different than those of a garage. We are sharing the essential upgrades required with you so that you can have a rough idea of the whole process and no one can overcharge you. The basic upgrades that you would need to do are as under:

  • A new ceiling to replace the roof will help support the drywall and insulation.
  • Putting a moisture barrier in between the slabs and the flooring.
  • Upgrading the garage by supplying the outlets with plumbing.
  • Windows and door placing and exterior finishing with interior amenities installation.


2. Should I Prioritize a Garage for an ADU Conversion Over a JADU Conversion?

The JADU (Junior Accessory Dwelling Unit) is the smaller version of an ADU actual dwelling unit that can stand alone independently. ADU and JADU must have their own separate entrance and kitchen. A JADU can have a shared bathroom with the existing home, while an ADU must have a separate bathroom.

ADU Types - GMJ Construction

Keeping in mind the difference between an ADU and a JADU, we will suggest prioritizing an ADU over a JADU. As with the separate independent living space, an ADU has its own utility bathroom, which increases its value over a JADU. As a result, the chances of renting an ADU increased.


3. Garage to ADU Conversions: Total Cost?

One of the best investments in maximizing apartment space and getting a high rate of return is to do a garage to ADU conversion. A garage to an ADU conversion for a 400 sq. ft. garage will cost $50,000. So, if you have a garage covering a larger square footage area, you will definitely pay more. But don’t worry; whatever you spend at this stage will generate significant revenue in the long run.

Total Cost of Garage to ADU Conversions - GMJ Construction


The reasons why a garage to ADU conversion will cost a bit more are:

  • You are taking out all the HVAC, water, and electricity extensions from the main home to the garage. Then their installation and quality operation make the process expensive.
  • Depending upon your garage-covered area, if it’s larger, it will require more work and materials, so that it will cost more.
  • Clearing out the permit to design the whole ADU will neck you a lot. So, handing over the job to the contractor will make you hustle-free but add an extra grand to the bill.
  • Additional foundation laying, quality insulation, and appropriate roofing make up the final budget.
  • Interior designing, flooring, paneling, and all sorts of final finishing will all depend upon your requirements. So, the more spacious you make your ADU, the more the conversion will cost.


4. Garage to ADU Conversions: Time Span?

If you are ready with the conversion clearance and have a good garage foundation in good condition, a garage to ADU conversion will take around 4-6 months. Your conversion can be even faster if you hire a good contractor like GMJ Construction Inc. There are a few elements that will define the time span of your garage to ADU conversion. A few of the most important are mentioned below.

The Condition of Your Existing Garage:

Some garages are well constructed and have a strong foundation with good-quality framing and roofing. For such garages, there would be no need to reconstruct the framing or relay the foundation. As major work will already be done, more time will be saved, and your ADU conversion will be completed in a short time span.

The Dimensions of Your Existing Garage:

If you have a small garage covering fewer square feet of area, it will require less work. A small garage conversion will cost less and save time than a more oversized garage. For a garage to be converted into an ADU, it should be larger than 150 Sq. ft.

Status of Utility or Code Permit

Any unpermitted garage will require you first to get a permit, which will take time. If your garage is already permitted and you also get the permit from your HOA (Homeowner Association) regarding the conversion, it will save a lot of time. And your garage to ADU conversion will take less time.

Availability of materials and type of contractor

Handing your garage to ADU conversion to a responsible and experienced contractor can make many things easier. In addition, they will complete the conversion in less time. A good contractor like GMJ Construction, Inc. will help you with the design and material selection process with their innovative design team. So, time span and time conversion will also depend upon the type of contractor.


5. Can I Do A Garage to ADU Conversion in An Illegal Garage?

Doing any construction in an illegal, unpermitted garage is discouraged by us. It would be best if you only opted for construction and conversions on a legally permitted site. If, for some reason, your garage or site is not permitted by the HOA and you want to legalize it before starting any work, then read the next step. You will find it helpful.


6. Are there Ways to Legalize an Unpermitted Garage?

If your garage is unlicensed and not permitted, the best practice is to comply with all the legal requirements and remove all illegal things. For example, if you have a garage with a window over it and having a garage with a window is not permitted, then simply replace the window with an actual wall to fill the window space.

Our suggestion is to hire an expert to inspect your garage. Then, acting as a middleman, he will seek out the laws of your HOA and enlist all those who have disobeyed them. Then he will share with you the possible ways to comply with the laws. As a result, you will legalize your garage and make it ready for an ADU conversion.


7. What to Do If Power Lines Pass Over Your Garage?

Power lines require an encroachment permit, which can be obtained by writing to the service provider. As a result, depending upon the company, they will leverage you to construct an ADU by remaining 5-10 ft lower than the actual lines.


8. Can a Granny Flat Be Built Above My Garage?

Most homeowners opt to build a granny flat over their garage to maximize a property’s potential and increase its value. Building up a granny flat is much more complicated than it might seem.

To build a granny flat over your garage, you must also make the exterior uniform. The granny flat shouldn’t appear as a building out of the box. If the newer granny flat looks out of place, it will decrease your property value and act as an unwelcoming gesture.

Building a granny flat will require more money. As a granny flat is a heightened structure, one has to ensure its strength to let it withstand the load. Extra flooring and roofing would be required to build the extra infrastructure above a garage.


9. Is It Worth Demolishing the Old Garage and Constructing a New ADU?

Considering the budget and build cost, constructing an ADU over a pre-built old garage is cheaper. But still, you must consider the condition of the garage. If your garage is under 50 years old with a good foundation and framing in good condition, then you can go for an ADU conversion with an old garage. Or else, if your garage is older than 50 years, we recommend demolishing the old garage and constructing an ADU from the start. An expert will test the framing and foundation quality and let you know whether building a new garage will be extraneous or valuable.


10. Is It Necessary to Reconstruct the Garage Foundation?

As most garages are built over slabs, it’s necessary to reconstruct the foundation. You can do it by applying a layer of concrete above the slabs by using a moisture barrier between them if your slabs are in good condition. If the slabs are cracked and in bad shape, then underpinning by digging a trench and adding a foundation is recommended.

A strong and rigid foundation can eventually give rise to a robust and earthquake-resistant building structure, so you must pay attention to foundations while doing a garage to ADU conversion.


11. Can I Add Separate Utilities To ADU?

Yes, you can add special utilities to your ADU and install separate utility meters, which will help track consumption in the event of renting the ADU. Establishing different water and power meters will cost you a couple of additional dollars, like $3–4 thousand, depending on your utility provider. Adding separate utilities will make you happy by thinking you have saved money, but eventually, when renting out both the ADU and your existing home. It will cause difficulty for both tenants regarding the bill.


12. Does ADU conversion also require building a separate parking lot?

No, there is no such rule as building separate parking for an ADU. For the sake of requirement, if you have extra space, you can allocate some for separate parking of ADU. It will encourage more buyers to prioritize it over an ADU with no parking.


13. Are Loans Given for Garage to ADU Conversions?

You can get easy, hassle-free loans with the lowest interest rates for ADU Conversions. To get a loan, you must be ready with your home papers, work history, and credit card details. Some essential loans that you can get for ADU conversions include:

Cash-out refinances mortgage loans:

Cash in this comes with no strings attached, and even the interest rates are lower. You can get an amount of cash equivalent to the percentage of the home’s current market value minus the outstanding mortgage.

Renovations, remodels, and construction loans:

In this loan category, you can get all the conversions fully funded by the loan. To get these loans, you would need a solid bid from a contractor. The loan lender will evaluate the future value of ADU and gives the loan considering that. These loans fully fund the conversions, so they have higher interest rates.

14. What Are the Property Taxes for Garage to ADU Conversion?

Whenever the property rate is raised, which is 1%, the tax rates for ADU conversions are also raised. For renting out an ADU, the total property tax will depend upon the construction expenses only because, according to the city evaluation, the garage was already present with the main house.


15. Can Both the ADU and the Actual Home Have Two Different Addresses?

Depending upon your state law and jurisdiction system, some countries will automatically consider an ADU a separate independent unit and allocate them a different separate address. While getting a separate address is optional, it’s up to you if you need it. You can write to the local judiciary. In some states, the ADU and the existing home are given the same address.


16. Is Garage to ADU Conversion Worth It?

ADU Conversions are worth the money. They not only add extra living space to the existing home but also increase the actual market value of the property. But in time, this living space can be rented. ADU conversions are the best way to create a separate independent living space for your family or rent it out. Building an ADU will be worth the money if you do not need your garage for vehicles.

If you are up for doing a garage-to-ADU conversion with a permitted legal garage to generate an extra cash flow, then building an ADU conversion is worth the money option for you.


Final Words

A garage to ADU conversion is ideal for creating a small separate residential unit. ADU can also serve as an excellent guest cottage. An ADU can be used as an independent private office or workspace and can even be rented out. The process of converting the garage into an ADU is cost-effective. Building an ADU conversion is the ideal way to create a small separate residential unit within the previous one.

Above, we have shared 16 essential questions and steps to follow if you opt for a garage to ADU conversion. They will be helpful. Starting up with a quality foundation on a legally permitted garage with an experienced contractor like GMJ Construction Inc. can make your garage to ADU conversion hustle accessible.

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