How much does an ADU cost in California?

Abodu Unit


September 8, 2021Backyard Living

Definition of a Prefab ADU

Prefab ADUs are self-contained living spaces that are built off-site in a climate-controlled factory and then delivered and placed at their final site. Prefab is short for “prefabricated” and is different from a stick-built ADU which is constructed in the same way your main home is, which is built on site. An ADU — or accessory dwelling unit — is a home that has a kitchen, bathroom and sleeping area that is either detached or attached to a primary residence. Whether you call it an ADU, granny flat, backyard cottage or something else, in order to be an ADU, the unit must have a kitchen and bathroom, otherwise it’s not considered a livable space and isn’t an ADU.

Growing popularity of prefab ADUs in California

California has seen a surge of popularity for ADUs in recent years mostly because the state legislature has passed a series of laws making it easier for homeowners to build ADUs. This comes in response to the growing housing crisis in the state, which ADUs can help combat as an easy solution for adding population density to existing residential land.

Advantages of Prefab ADUs

There are many advantages to buying a prefab ADU instead of going with a stick-built ADU, like fast turnaround times, cost-effective designs, and the inherent sustainability of prefab ADUs.

Speed and efficiency of construction One of the key advantages of a prefab ADU is the fast construction process. Since they’re built off site in a controlled environment, construction can happen simultaneously with site preparation, and regardless of any adverse weather that might slow down a stick-built ADU. This efficiency can allow homeowners to have a fully functional living space in a fraction of the time required for traditional stick-built methods.


Prefab ADUs are a cost-effective option because the climate-controlled environment eliminates the possibility of weather delays and material waste. Plus, the standardized designs and materials reduce the architectural planning and engineering you’d have to pay for if you opted for a stick-built ADU. You can also save on labor costs since the assembly and construction of prefab ADUs require less time and manpower.

Customization options

Prefab ADUs eliminate the need to develop a design from scratch alongside an architect and engineer, but many people wonder how customized they can be. Many prefab ADU builders offer custom finishes like siding and roofing materials, paint colors, and interior finishing from the floors to the appliances.

Sustainability and eco-friendly features

The nature of prefab ADUs means less material waste, making them a more sustainable option than stick-built ADUs. Many prefab ADU builders also offer eco-friendly materials and energy-efficient appliances and upgrades.

Factors Influencing the Cost of Prefab ADUs

There are many factors that impact the final cost of a prefab ADU, including the builder you decide to go with, the design and features you choose, and of course, the site preparation that will be unique to your ADU project.

Size and layout of the ADU

Obviously the size and layout of a prefab ADU will impact its overall cost — the larger and more complex the design, the more expensive it’ll be. The layout and interior features, like the number of rooms, bathrooms, and kitchen appliances will also affect the final price.

Design and architectural features

Customization options like high-end finishes, specialized windows and doors, or unique architectural details will ultimately impact the final cost. It’s important to strike a balance between aesthetics and cost, and ultimately the functionality you’re hoping to achieve with your ADU.

Location and site preparation

The location of the ADU and the site preparation requirements can also affect the final cost. When embarking on an ADU project, consider the condition of the site, accessibility, and the need for utility trenching and other infrastructure. Sites that need a lot of grading, leveling, and utility trenching will have higher costs.

Additional features and upgrades

Features like high-end appliances, custom cabinetry, premium flooring, smart home technology, and upgrades like solar panels will all add to the final cost of your ADU.

Let Abodu Create the Perfect Backyard Home

Abodu is a trusted partner for homeowners wanting to add a prefab ADU to their property. We offer a variety of floorplans that have all been designed by world-renowned architects and offer a highly livable space with small footprints. Our white-glove service is what really makes us stand out from the crowd: with Abodu you get a dedicated project manager that handles everything from start to finish. Check out our ADUs in person, book a tour at a showroom today.

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