The Town of Hillsborough has updated its ADU ordinance to comply with new state laws. Below are the up-to-date requirements to build an ADU in the city.
Updated Sep 23, 2021
All properties zoned for single family, two-family or multifamily may be eligible to build ADUs.
Number of units
The number of ADUs you’re able to build depends on how your lot is zoned:
Lots zoned for single family use may add 1 ADU and 1 Jr. ADU (JADU).
Lots zoned for two-family or multi-family may add up to 2 detached ADUs per lot or up to 25% of the existing units in the building if conversions of existing non-living space.
The maximum ADU you can build depends on the ADU type:
The maximum size is 500 sq. ft. for a JADU
850 sq. ft. for a one bedroom detached ADU
1,400 sq. ft. for a 2 bedroom detached ADU
Attached ADUs can be 800 sq. ft.
Detached ADUs can reach a maximum height of 32 feet. Attached ADUs can reach the same height as the main structure.
Minimum setbacks of 4 feet from the side and rear lot lines.
For 1-2 bedrooms, one parking spot required. For 3+ bedrooms, two parking spots are required. No requirements for parking if any of the following true:
The accessory dwelling unit is located within one-half mile walking distance of public transit.
The accessory dwelling unit is located within an architecturally and historically significant historic district.
The accessory dwelling unit is part of the proposed or existing primary residence or an accessory structure.
When on-street parking permits are required but not offered to the occupant of the accessory dwelling unit.
When there is a car share vehicle located within one block of the accessory dwelling unit.
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 the town.
Are you in a creek protection area? Do you have a utility easement over your property? Reach out to us and we’ll help you build a custom ADU to fit your unique property characteristics and local regulations!
Want to learn more about ADU regulations in your area?
Book a free consultation and estimate with a Cottage ADU Expert to find out what’s possible on your property!