Could ADUs help solve California’s housing crisis?

California's housing crisis may find partial relief through accessory dwelling units, or ADUs, which are experiencing unprecedented growth statewide.

These secondary dwellings, commonly known as "backyard cottages" or "granny flats," allow property owners to construct additional rental units on their existing lots.

ADUs now represent approximately one in six of all newly permitted housing units across California, driven by streamlined approval processes that require less regulation and review than traditional development projects.

San Diego has emerged as a particularly aggressive adopter of ADU development through a unique local policy that permits property owners to build a "bonus" ADU for each unit designated for lower-income tenants.

In areas lacking nearby public transportation, individual properties can accommodate up to five total units, while properties in designated "transit priority" areas face fewer restrictions on affordable ADU construction.

This approach has generated ambitious projects that resemble apartment complexes rather than traditional accessory units, with the largest proposed development containing 148 units.

The ADU boom presents significant opportunities for California property owners seeking additional rental income while contributing to the state's housing supply.

However, the rapid expansion faces growing scrutiny from critics who question whether developers are maintaining affordability commitments and worry about neighborhood character changes.

As California grapples with some of the nation's highest housing costs and rising eviction rates returning to pre-pandemic levels, the effectiveness and regulation of ADU programs will likely remain central to statewide housing policy discussions.