The 3 Challenges You Will Face When Building Your ADU


Approval Process

Navigating the legal requirements of building an ADU can be a challenge for homeowners. From the permitting process to understanding exactly what is required, 50% of homeowners report difficulty meeting their city/county’s development standards. Even architects often cannot understand the complexities and protocols associated with getting government approval and permitting. In particular, California has recently embraced these developments through SB-9, but some local municipalities are still slow to accept them because the regulations are so new. As a result, it’s important for both homeowners and architects to understand all the requirements in order to go forward with building an ADU that is approved by their jurisdiction.

Filing for permits is an essential part of the ADU building process, and it is important to plan ahead in order to avoid any delays or issues that could arise. It can take longer than expected to obtain approval from the local authority – up to six months – and submitting last minute requests may not give you the desired quick-start that you’re hoping for. Make sure to initiate the permit request process promptly and get acquainted with your jurisdiction’s requirements in advance. This way, you can ensure that there are no hurdles between you achieving your goal of constructing a safe and quality ADU.

Design Limitations

Homeowners looking to build an ADU must pay special attention to design limitations when creating their projects. ADUs are fully new builds that require the expertise of architecture and engineering professionals, as they extend outside of the house and can affect others. To ensure a successful build, it is important to adhere to pre-approved plans under the Standard Plan Program. These plans are designed by private licensed architects and engineers, reviewed for compliance with building, residential, and green codes, and can cater to a variety of site conditions. Following these guidelines is paramount for every successful ADU project.

These regulations include lot, setback and height limits, Floor-Area-Ratios (FAR), lot coverage, open space and minimum lot size. The UC Berkeley Center for Community Innovation states that properties with no ordinance regulating ADUs can build units up to 1200 square feet, 16 feet tall with four-foot side and rear yard setbacks. All other jurisdictions have their own ordinances which would limit an ADU to 850square feet or 1000 square feet if the unit has two bedrooms or more. However, there is a statewide exemption ADU option available that allows construction of larger sized living areas without any restrictions imposed by local ordinances. It is advisable to seek legal guidance as soon as possible when considering building an ADU as regulations can change over time and are subject to a variety of conditions.

Accessing the sanitary sewer and water service for an ADU requires careful planning to ensure that it coordinates with the primary residence. Connections can be made through a basement in the main residence and electricity services require a new meter which allows the ADU to pay its own way. Making sure that connections are secure and properly planned ahead of time will save trouble and money down the line. Investigate local ordinances in your area to be familiar with all regulations concerning ADUs before making any decisions or major investments.


It is surprisingly challenging for homeowners to finance the construction of an ADU, even those that are more affluent than the typical Californian homeowner. In this survey, 24% of homeowners cited paying for cost of construction as their top challenge and a further 5% struggled to obtain financing. Ultimately, 62% of them had to rely on cash savings or money from friends or family in order to make it happen. While this may be hard for most homeowners California has started an ADU grant to aid its residents who are looking to build an ADU.

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