Building an ADU Above Your Garage: Here’s the (Second) Story

Did you know that the California state government has recently relaxed the rules and restrictions around building an ADU above garage (Accessory Dwelling Unit or Additional Dwelling Unit) in Los Angeles and throughout Southern California?

This is exciting, as you can now consider building a secondary housing unit with independent living facilities on a residential lot. If you’re worried about finding space on your property to add an ADU (or if you don’t want to convert your garage), you can consider building an above-garage ADU!

Here at GreatBuildz, a free service that connects homeowners in Los Angeles, Orange, Ventura and San Diego Counties with reliable ADU contractors, we speak to homeowners every day about planning their desired ADU above your garage project and budgeting for ADU construction costs – here are some ideas & tips to get you started.

An ADU is an additional living unit on a property, and building one above your garage can be a perfect way to add space while leaving the garage itself to park and store your vehicles.  

However, before you run off to meet contractors, here are some things you need to know about building an ADU on top of the garage.

Key Takeaways

  • Constructing an above garage ADU is an investment, offering opportunities for passive income through renting out the unit and contributing to increased property value. The return on investment (ROI) may justify the initial construction costs.
  • The average cost of building an above-garage ADU ranges from $200,000 to $350,000, considering a size of 350-500 square feet. However, costs can vary based on factors such as contractor rates, materials, and post-construction expenses.
  • Simplifying the design, opting for an outdoor stairway instead of an interior one, and stacking the ADU directly above the garage corners can help reduce construction costs.
  • Beyond rental income, an ADU on top of garage can serve various purposes, including providing space for seniors or guests, creating a home office or workout space, and accommodating adult children.
  •  Enhance the ADU’s appeal and functionality by incorporating large windows for natural light, choosing space-enhancing colors, optimizing storage, and selecting convertible furniture. These design elements contribute to a brighter, more spacious living environment.
  • The ADU construction process involves designing plans with a professional architect, obtaining pre-approved loans, securing design approval from local building departments, and hiring a reliable ADU contractor. Thorough preparation, including providing detailed plans and material preferences, facilitates smoother contractor interactions.

Benefits of an ADU Above Your Garage

One primary benefit of an ADU over garage is that it is an investment. An ADU also provides a large amount of space for a multitude of potential uses.

Related: 10 Most Popular Use Cases for an ADU

ADU above your garage Los Angeles

Photo Credit: Durham Construction


There are two ways you can earn from your ADU:

  1. Rental Unit to Earn Passive Income

You can design an ADU with a separate entrance, kitchen, bathroom, and bedroom and then rent it out to short-term or long-term tenants.

  1. Increased Property Value

According to Forbes, more homeowners are willing to pay for properties with ADUs attached as they see the benefits of using them for additional living spaces or investment/rental purposes.

In general, building an ADU above the garage might come with a significant cost, but the return on investment (ROI) should make that cost worthwhile.

Estimated Cost of Building an ADU Over Garage

According to Kol Peterson at, the building cost of an above-garage ADU averages around $200,000-$350,000. Although an ADU in California can be up to 1,200sf, building an ADU over a 2 or 3 car garage will likely be 350-500sf, enough for a studio or one-bedroom unit.

Based on hundreds of homeowners we’ve spoken with and projects we’ve seen here in Los Angeles and Southern California, we’d say this average is fairly accurate, assuming a fairly straightforward process. The cost of construction for the same structure can vary greatly depending on the contractor, as well as the current cost of labor and materials.

Also, you should consider the post-construction and after-construction insurance costs of building out the ADU, as well as the cost of ongoing maintenance.

Like any building project, the importance of getting quality experienced contractors factors greatly into the cost and quality of their work.

Building an ADU Above Your Garage: Here's the (Second) Story 1

The costs of building an ADU over a garage will depend on quite a few factors. Some projects will require more labor or materials, and the complexity and amount of work required vary from one garage to another. Importantly, the existing structural foundations of garages vary and will certainly impact the costs of an ADU above garage.

Here are a few things that will impact the costs of your ADU above your garage project:

  • Adding an entire second story about the garage could require refinishing the entire exterior of the structure (stucco, siding, etc)
  • Your ADU above garage plans will likely require various additional garage structural support to handle the weight of the second-level ADU
  • There are significant costs to running utilities (gas, electric, water, waste) to your ADU
  • The addition of stairs and a new roof
  • Older garages often require more expense to make improvements or bring them up to today’s code/standards
  • Reinforcing old foundations to support the 2nd floor

The property’s age has a significant influence on the final bill. However, if you rent out the unit or sell your house in the future, the return on investment (ROI) might be worth it.

Pro tip: You can save costs on the construction of your second-story ADU above a garage by considering a simple design. If you stack your ADU living space directly above the four corners of your existing garage, that is likely to save you costs on framing, structural elements, and other costs.

If your area allows it, planning for an outdoor stairway will also save costs rather than an interior staircase, as you won’t need to add interior space to the first/garage level floor.

Renting Out Your ADU

There are some guidelines that you need to take note of when renting out an ADU, but generally, it works just like a typical rental accommodation. You will need to decide the lease terms and the rental amount. You can check for more information on Los Angeles rental laws for ADUs here. 

The Uses of an ADU Over a Garage

Build an ADU over your garage

Photo Credit: Bau10 & Paul Vu

A common reason to consider building an ADU is to increase your living space. Here are some uses for an ADU: 

1. A Space for Seniors or Guests

Building an ADU for grandparents or other elderly relatives allows the family to care for them closer to home while also enabling them to live independently. An ADU can also act as a guest room during holidays.

2. The Ultimate Home Office or Workout Space

Many people work from home, and an ADU above your garage can be a perfect space for a home office. Away from the noise of the main house, this can also be an excellent place to put a study room or workout space.

3. A Room for Adult Children

With rental prices increasing, it may be a good idea to add an ADU for adult children. They can stay in the extra space and still maintain a high degree of independence. 

Ideas & Tips For an ADU Above Your Garage

Now that you know the benefits of building a 2nd story ADU, here are some tips to keep in mind when doing so:

1. Add Light With Large Windows and Layered Lighting

Above garage ADU

Natural light makes a small space feel more spacious and helps improve the mood. Glass panels and skylights are both excellent ways to do this, and high clerestory windows will only allow sunlight in while maintaining privacy, which is especially good for bedrooms or bathrooms.

Layered lighting can also help create a bright, airy space. Think about all the sources of light that you could incorporate in addition to natural light. Recessed can lighting creates an elegant look that lights up large spaces and can be complemented with pendant fixtures for areas that need more light, like a dining room or bedroom.

2. Choose Colors That Make the Space Look Bigger

White is often used to paint a second-story ADU because it complements almost every color on the color wheel and works well in most color schemes. White reflects light, brightening the room and making it appear larger. However, other brighter color schemes will also do the trick of making the space bigger.

3. Optimize Storage to Free Up Livable Space

Design built-in shelves and cabinets into your accessory dwelling plan whenever possible. Storable and convertible furniture will also help save space — from storage ottomans to foldaway beds. 

The Process of Building an ADU Above Your Garage

Below are four steps to building your second-story ADU.

1. Design the ADU plans

Design ADU above garage plans

Hire a professional architect. An architect will help you determine what you need and work with you to develop your 2nd story ADU plans.

Make sure your architect is well-versed in the zoning and building codes in Los Angeles or your Southern California City. Although ADUs are allowed throughout the state of California, every city could have its own specific guidelines. For example, they are likely to have height restrictions or limitations that could impact building an ADU on top of a garage.

2. Get a Pre-approved Loan (if needed)

After finishing your ADU plans, apply for a pre-approved loan with your bank or other financial institution.

Related: ADU Financing Guide

3. Get the Design Approved by the Los Angeles Building Department

Apply to the building department to get your plans approved. If your blueprint meets regulations, it will be approved. After that, you can start the application for a construction permit. If you are using pre-approved plans from the city/county, that may streamline the process.

4. Find a reliable ADU Contractor

You will need to check with your contractor on the duration of the work and the progress payments required for the ADU project. The timeline for processing the project paperwork, loan, and project construction is about six to nine months. Here are some tips to help you find an ADU contractor

The more prepared you are to meet with contractors, the better off you’ll be. You can provide each contractor a set of plans to bid, but ideally you would also provide each contractor an ADU scope checklist which will detail all the items you expect included in your estimate/project. You would ideally also include as much information as possible about the materials you intend to use.

Even if you haven’t chosen the exact material…its good to let the contractor know about such things as flooring (tile, wood, carpet), roofing style, cabinets and countertops, exterior material (stucco, siding), etc.

Potential Challenges and Solutions

Constructing an ADU above a garage presents various potential challenges, necessitating foresight and strategic planning for successful project completion. Let’s look at some common ones you might come up against.

Challenge Solutions
The identification of unexpected structural issues in the existing garage, which may require additional modifications for safety and compliance
  • Conducting a thorough pre-construction inspection
  • Engaging experienced structural engineers
  • Allocating a contingency budget to address unforeseen changes
Delays in the construction timeline can arise due to weather conditions, material shortages, or permit processing times
  • Realistic scheduling
  • Choosing construction periods with favorable weather
  • Staying proactive in permit applications
  • Coordinating with suppliers to secure necessary materials in advance helps prevent delays
Neighborhood resistance or compliance with zoning regulations
  • Engaging in open communication with neighbors
  • Addressing concerns
  • Working closely with local authorities to ensure adherence to zoning laws
Legal challenges
  • Consulting with legal professionals to navigate any regulatory complexities or disputes that may arise


Effectively anticipating and addressing these potential challenges ensures a smoother ADU construction process, enhancing the overall success and satisfaction of homeowners undertaking this transformative project.

When it comes to building an ADU above your garage, you shouldn’t have to go it alone – GreatBuildz can help simplify your renovation experience.



GreatBuildz is a free service that connects homeowners in Los Angeles, Orange County, Ventura or San Diego with reliable, thoroughly screened general contractors and provides project support from start to finish. Call now (818.317.3567) to chat with a real person about your next remodel project or visit our website for more information:

Hi, we're Paul and Jon - Co-Founders of GreatBuildz. We believe everyone deserves to find a great contractor, have a stress-free renovation, and enjoy their beautiful new space. There are so many contractors out there and it's often hard to tell the good from the bad... until it's too late. We started our company to help simplify your contractor search and help you have a stress-free renovation experience. We're always available to help, no matter where you are in the process. Click here to learn more about our story.

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