All properties zoned for single family and multifamily use may be eligible to build ADUs.
Number of units
Lots zoned for single family use that have an existing dwelling are permitted to add 1 ADU and 1 Jr. ADU (JADU).
Maximum square footage is determined by your ADU type:
- 500 sq. ft. for a Jr. ADU (JADU)
- 800 sq. ft. for a detached ADU if the existing home has reached the maximum lot coverage (60%)
- 1,200 sq. ft. for a detached ADU
Detached ADUs can reach a maximum height of 16 feet. Attached ADUs can reach the same height as the main structure, assuming they comply with municipal code (including daylight plane).
Homes located in specially-designated FEMA Special Flood Hazard Areas (Flood Zone) are typically required to build an elevated floor that is higher than the highest level of projected flood waters. If the property is located within a Flood Zone, the ADU may exceed the 16-foot height limit in order to provide an elevated living area that meets FEMA regulations. However, to keep the height exception at a minimum, the interior ceiling height of the living area cannot exceed 8 feet.
Conversion of existing unfinished basement space can be used for an attached ADU.
Minimum setbacks of 4 feet from the side and rear lot lines, as well as 6 feet from any existing structures are required for detached ADUs.
If the ADU is more than 75 feet from the front property line and adjoins a neighboring required rear yard, this requirement does not apply. Also, if the ADU is converted from an existing structure, the setback requirement does not apply.
No additional parking is required for ADUs if they are within 0.5 miles of public transportation (a bus stop, train station, etc.). All of Alameda is located within a half-mile distance of public transit except some locations on Creedon Circle (if you are located on Creedon Circle, it's still worth consulting with a Planner). When converting a garage or carport, replacement parking is not required.
Owner occupancy is not a requirement for permitting an ADU from January 1, 2020 until January 1, 2025. This is a great opportunity for rental property owners to increase their yields in a cost-effective way.
While long-term rentals are permitted for ADUs, short-term rentals (e.g. Airbnb for less than 30 days) are not permitted in Alameda.
Do you have a utility easement over your property? Are you in a FEMA flood zone? Reach out to us and we’ll help you build a custom ADU to fit your unique property characteristics and local regulations!