ADU: Accessory Dwelling Unit (California)

Since 2017, the State of California has allowed the permitting and building of Accessory Dwelling Units (ADUs) on single-family-zoned properties throughout the state. Starting in 2020, that ADU law has expanded to allow for a second ADU to be permitted on a single-family-zoned parcel, subject to locality constraints. This expanded law deputizes every homeowner, as a developer, to construct up to 2 rental units on their property: one full-sized (≤1200sf) detached ADU and one junior ADU (≤500sf) attached to the primary residence. Typically, ADUs convert a garage into occupiable space, which offers a significant discount in building and permitting costs compared to new ground-up construction.

This law is one means to address the persistent housing shortage facing California residents. ADUs are also an incredibly affordable way to create rental income for property owners and can often add significant resale value to the property. Many California residents have already developed thousands of ADUs across the state; you may have even seen some in your neighborhood or city. Additional density is how future cities will thrive and 323 Collective is proud to help lead this innovation: since 2018 we have been closely involved in nearly a dozen ADU projects.