All About ADUs with Garages

An accessory dwelling unit or ADU with a garage is one of the most efficient ways to add housing while preserving parking, storage, and yard space. Homeowners can build an ADU above a garage, often called a carriage house, design an ADU with an attached garage, or construct a detached garage alongside a new ADU. SnapADU specializes in designing these structures as new construction so they meet modern structural, zoning, and energy requirements from day one.

ADUs With Garages: Key Takeaways

• An ADU can be built above, attached to, or alongside a garage.

• Building an ADU over a garage maximizes space without reducing yard area.

• Most cities in San Diego County allow above-garage ADUs when height & setback limits are met..

• The garage does not count toward the ADU square footage limit.

• Typical projects with a new construction garage range from $350,000 to $500,000+ depending on size and site conditions.

• SnapADU designs ADUs with garages as fully customizable stick-built construction to meet California code.

Types of ADUs with Garages

Above-Garage ADU aka Carriage House

An above-garage ADU places the living space on the second story while the ground level remains dedicated to parking or storage.

ADU With an Attached Garage

In this configuration, the ADU with a garage shares a structure but remain functionally separate, similar to a single-family home with an integrated garage.

ADU With a Detached Garage

Some homeowners build a new garage and ADU as two separate structures to allow more flexibility in layout and setbacks.

Garage Conversion ADU

A garage conversion accessory dwelling unit repurposes an existing garage into a fully functional ADU. This option is often the most cost-effective since the structure already exists, but only if the structure is in good condition.

Can You Build an ADU Above a Garage?

Yes, California law allows ADUs to be constructed above garages when local height limits and zoning requirements are met. Many cities specifically allow this configuration because it increases housing density without expanding a home’s footprint.

Carriage House Meaning and Origin

ADUs above garages are often referred to as carriage houses. The term “carriage house” dates back to the 18th and 19th centuries, referring to outbuildings designed to store horse-drawn carriages. Over time, as automobiles replaced carriages, these spaces evolved into living quarters for staff or rental housing.

In modern real estate, carriage houses have become synonymous with above-garage ADUs, particularly in urban and suburban settings where homeowners seek efficient ways to add livable space while retaining valuable storage and parking space.

Benefits of Building an Above-Garage ADU

An ADU above a garage allows homeowners to add livable square footage without expanding the footprint of their home when there is an existing garage.

Rental Income. Building a carriage house can generate passive income by renting it out as a long term or short term rental. Homeowners in cities with high rental demand like San Diego can see significant returns by utilizing this extra space. Read more about renting your ADU.

Multigenerational Living. ADUs above garages are a great solution for housing aging parents, adult children, or guests while maintaining privacy. They offer a separate, self contained space with close proximity to the main home while retaining valuable parking. Read more about multigenerational living with ADUs.

Property Value. A well designed above garage ADU increases property resale value. Buyers recognize the benefits of extra living space and rental potential, making these units a smart long-term investment. Read more about investing in an ADU.

Requirements for an Above-Garage ADU

Zoning and Permitting Regulations

Before starting your above-garage accessory dwelling unit plans, it is essential to look into local zoning laws and ADU regulations. Many cities have specific regulations such as the following:

• Height restrictions (typically 16 to 25 feet max, but will depend on specific property zoning).
• Setback requirements from property lines. Required setbacks are often greater for two story structures.
• Parking regulations (most cities waive parking if near public transit).

Regulatory expertise is an area where SnapADU stands out. To learn more about whether you are able to build an ADU above your garage, start with our summary below, and reach out to our expert team with questions about your property.

TABLE: ADU Over Garage Regulations By City

Source: SnapADU & local regulations

Cost of Building an ADU With a Garage

Factors That Affect Costs for an ADU with a Garage

Building an ADU with a garage above typically costs between $350K and $500K+ all-in. The all-in ADU cost depends on several key factors. The size and design complexity play a significant role, as larger or more intricate layouts require more materials and labor.

Custom features such as upgraded finishes or high-end appliances can further increase expenses. Since prefab construction is not an option for ADUs with garages, all builds require traditional, stick-built construction, making careful budgeting essential.

Structural Considerations (especially for Garage ADU Conversions)

If the homeowner is looking to utilize an existing garage to create an ADU or build above an existing garage, a structural engineer must assess the garage’s foundation and load capacity.

Reinforcements may be required to meet safety codes. In many cases, it makes more sense to demolish the existing garage and start from scratch, which is what SnapADU specializes in. We recommend taking a read through our blog post on garage conversions vs. demolition before starting your ADU garage plans.

Financing Options

Several ADU financing options are available to help homeowners fund their ADU projects. Home equity loans allow homeowners to leverage the value of their existing property, making them a popular choice for ADU financing.

Construction loans are another option, providing funding specifically for building projects and allowing for phased payments as the work progresses.

Exploring these financing options early in the planning process can make budgeting for an above garage ADU more manageable. SnapADU can help connect you to reputable lenders.

Popular Above Garage ADU Floor Plans

Studio & One Bedroom Layouts

Studio and 1-bedroom above garage ADUs typically range from 400 to 600 square feet, making them an efficient use of space while still providing a fully functional living area.

These units are most commonly built above a standard two car garage, offering a compact yet comfortable design. A well planned 500 sqft one bedroom carriage house can include an open concept living area, a full kitchen, a private bedroom, and a bathroom.

Two & Three Bedroom Layouts

For homeowners looking for additional space, two and three bedroom layouts typically range from 700 to 1,000 square feet. These larger units are often built above a 3 car garage or a 2 car garage with extra storage space.

For example, our 750 sqft two bedroom carriage house plan features an open living and kitchen area, two well-sized bedrooms, and a shared bathroom, making it a great option for small families or tenants who need more space.

Alternative Layouts

Not all above garage ADUs are designed with a full garage underneath. Some homeowners opt to use the first floor for storage instead of parking, creating a two story ADU with flexible usage.

An example is our modern two-story ADU in Pacific Beach, where the ground level serves as storage while the living space is located upstairs. Other designs incorporate a hybrid approach where part of the first floor is a garage and the rest is used as living space with additional living space upstairs.

An example of this is this custom two-story ADU in Oceanside where there is one bedroom and a garage downstairs and living space with a deck upstairs. Because carriage houses are stick-built, there is significant flexibility in design, allowing homeowners to create layouts that best suit their needs.

ADUs With an Attached Garage

For homeowners who need extra storage, parking, or workspace, an ADU with a garage offers a practical solution. Unlike an above-garage ADU, this design keeps both structures at ground level, making it a more accessible option.

The garage can be used for vehicle parking, additional storage, or even as a workshop while the ADU remains a separate, fully functional living space. An attached garage can later be converted into extra living space or a home office if parking is no longer needed for the ADU. See ADU projects with garages.

Key watchout: Setbacks for garages attached to ADUs may not be reduced

Keep in mind that garages may be subject to different setbacks than an ADU. Typically, garages will be subject to underlying setbacks for the property, even though the ADU may enjoy reduced setbacks. However, there are additional details to be aware of.

For example, in San Diego, when it comes to alleyways — with 15′ alleyways being quite common — garages need to maintain a setback of 6′ from the rear property line:

“Where access for parking is taken from the alley and the parking spaces are not parallel to the alley, a minimum distance of 21 feet shall be provided between the edge of the alley public right-of-way opposite the lot and the outside edge of the parking garage or parking stall closest to the alley (San Diego Municipal Code, Article 1: Base Zones, Division 4: Residential Base Zones, §131.0443 Setback Requirements in Residential Zones).”

ADUs with a Detached Garage

We have also taken on projects in which the homeowner chooses to build an ADU and a detached garage such as this 1,200 sqft ADU with a large two car garage in Rancho Santa Fe.

This is another option to consider when the property has extra space and the homeowner prefers separation between the ADU and garage. It is important to note that like for attached garages, detached garages will also follow setbacks and lot coverage per underlying zoning.

Detached Garage ADU Conversions

Garage conversions provide an efficient way to create an ADU without the cost of constructing a brand-new structure. Since the foundation, walls, and roof already exist, a conversion can reduce overall construction time and expenses.

However, conversion projects can be more unpredictable. Any time you are working with an existing structure, you are opening up potential pre-existing issues that may need to be brought up to code.

For instance, existing garages may require reinforcements, particularly if they were not originally built to residential standards.

Garages typically lack plumbing, insulation, and electrical systems suitable for living spaces. Upgrading these systems is of course necessary. Read more about converting vs. demolishing and rebuilding a detached garage ADU.

Choosing the Right Builder

Selecting the right contractor is crucial when building an ADU with a garage. Working with a knowledgeable designer and builder who has extensive experience with ADU projects ensures that your project meets local zoning laws, structural requirements, and quality standards.

Not all ADU builders specialize in above garage construction, so if building a carriage house, it’s essential to choose a contractor familiar with the unique challenges these projects present. Other important factors to consider include transparent pricing, clear project timelines, and a strong portfolio of completed ADUs.

Checking client reviews and past projects can also provide insight into a builder’s reliability and craftsmanship. Read more about what to look for in a reliable ADU company.

Working with a team experienced in garage-based ADUs helps avoid costly redesigns and ensures the project is planned correctly from the start. SnapADU has delivered these projects across San Diego County and understands how to navigate height limits, setbacks, and structural requirements unique to ADUs with or above a garage.

Frequently Asked Questions