ADU
An accessory dwelling unit (ADU) is a self-contained residential unit located on the same lot as a primary single-family home, taking the form of a detached backyard cottage, converted garage, basement apartment, or above-garage suite. ADUs have become a popular vehicle for STR investment because they can generate rental income without requiring a separate property purchase. Many US states, including California, have streamlined ADU permitting to address housing shortages, though local STR regulations may still restrict or prohibit ADU rentals in some jurisdictions. A well-positioned ADU in a high-demand market can achieve occupancy rates comparable to dedicated vacation rental properties while keeping operating costs low.
Frequently Asked Questions
Can I use an ADU as a short-term rental?
Whether an ADU can be used as an STR depends on your local zoning ordinance and STR regulations. Some jurisdictions that permit ADUs for long-term rental or owner-occupied homesharing explicitly prohibit ADU use for whole-home short-term rentals. Others allow ADU STR operation with a valid host permit. California, which has aggressively expanded ADU rights, leaves STR regulation to individual cities, resulting in highly variable rules even within the same metro area. Always verify local STR ordinances before purchasing or building an ADU with STR income in mind.
How much can an ADU earn as a vacation rental?
ADU vacation rental earnings vary significantly by market, location quality, and unit size, but well-positioned ADUs in high-demand markets can generate $25,000–$75,000 in gross annual revenue. Smaller markets and secondary locations will yield substantially less. ADUs benefit from relatively low operating costs compared to full standalone properties — they share property insurance, outdoor maintenance, and sometimes utilities with the primary residence — which supports attractive profit margins even at moderate revenue levels.
What permits are needed to build and rent an ADU as an STR?
Building an ADU typically requires a building permit from the local building department, covering structural, electrical, plumbing, and fire safety compliance. Once built, the ADU must receive a certificate of occupancy before being occupied. To rent it as an STR, you will then need to comply with local STR regulations, which may require a separate host permit, business license, and lodging tax registration. The permitting pathway for new ADU construction combined with STR operation involves coordination across multiple city departments.
Does an ADU need its own address to be listed as a vacation rental?
Most OTA platforms require a unique, accurate address for each listing. If an ADU has been formally assigned a separate address by the city — common for detached ADUs and required in some jurisdictions — this simplifies the listing process. For ADUs without a distinct address, hosts typically use the primary property address with a unit designator (e.g., 123 Main Street, Unit B). Some jurisdictions require a formal address assignment before issuing an STR permit for an ADU, so verifying local requirements early in the process is advisable.
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