Rightsizing Your ADU Project: ADU Jurisdiction Requirements (pt 1 of 4)

Creating an ADU is an important decision for any homeowner. ADUs have incredible utility for families and allow for unprecedented intergenerational wealth building.  They are essentially small homes which are typically, but not always, built in backyards of urban homeowners in single family neighborhoods. As small homes, ADUs are a significant investment for the typical homeowner and must be designed to work within an owner’s ability to pay or finance the project. ADUs are also subject to the legal constraints as well as physical site conditions that inform the design. To get an ADU project to provide a maximum value to a family it must be the right size. Not too large or costly and not too small which would reduce its utility and value. To get to “a right size” is one of the most important goals of the design phase for an ADU project. 

In order to rightsize your project, research the jurisdiction constraints for the property. The State of California created the base laws that enable all California residential property owners to construct ADUs without additional parking and other requirements that deterred construction of this important prototype. The state has recently updated their ADU handbook. It is important to understand these formative codes and it’s a great place to start by downloading and reading through this informative handbook. It is also important to go further and understand local codes as well. Most cities and counties have their own ADU guidelines and many of these jurisdictions allow for taller ADUs than the 18 feet allowed by the state (18-foot height limit allowed if the project is within ½ mile of transit; otherwise, 16 feet). Increasingly, cities and counties are going to 20 or more feet as a height limit. A 20-foot height limit allows for a two-story ADU which has great implications for the process of right sizing as less site area is required to meet programmatic requirements. Go to the planning department website of your local jurisdiction for local ADU requirements. One important note - :the state allows for an ADU of up to 750sf to be built without any additional “impact” fees placed upon it by the local jurisdictions. Over 750sf, you may be subject to school fees and other development fees. Again, check with your local jurisdiction.

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