San Mateo updates its ADU rules

The maximum unit size for detached ADUs was increased from 640 square feet to up to 1,200 square feet to align with state law. A lot with a single-family residence can be developed with an ADU and Junior Accessory Dwelling Unit, or JADU, for a total allowance of three dwellings, the city said. Parking requirements for ADUs remain one parking space per ADU or bedroom, whichever is less. State law provides parking exceptions that make most residentially zoned parcels in the city exempt from providing parking onsite. Existing permitted ADUs are not affected by the changes. Property owners of unpermitted ADUs can obtain permits and defer correction of code compliance issues, so long as the violation is not a health and safety issue, Brennan said.

“The intent is to reduce some of the potential privacy and view impacts of detached ADU development on adjacent properties while the community is providing feedback or while staff is collecting feedback from the community on the matter during phase two,” Brennan said.

The council established maximum building height for detached ADUs to 16 feet to the top plate and 24 feet to the top of the roof ridge, as measured from existing grade, to allow for two-story detached ADUs for property owners, the city said.

“If we’re trying to accomplish getting our codes into compliance, then I think it makes sense to act … to approve the proposed phasing and approach and the resolution with the amendment of measuring the top plate to the bottom plate at 16 feet with a maximum height of 24 to ridge,” Councilwoman Amourence Lee said.

Staff initially proposed a maximum building height of 16 feet measured from existing grade to the highest roof ridge but received pushback from Lee and Deputy Mayor Rick Bonilla because it reduced height limits and did not do enough to encourage ADU construction. Bonilla initially asked for a motion to deny the ordinance, but the council decided to modify it.

The updates align with state legislation around ADUs that went into effect in 2020. The updates will bring San Mateo’s local ordinance into compliance with changes. California has passed several ADU housing reforms in recent years that have made it easier to apply and develop ADUs. San Mateo has seen an increase in ADU permit requests, with 16 applications in 2017 to 88 applications in 2020, although only 52 were approved and 35 were completed.

The ordinance change is part of a two-phase process from the city, with phase one updating the local ordinance to meet state regulations, while phase two will focus on community outreach until July and August. The pandemic delayed outreach to the public about planned changes to the ordinance.

Councilwoman Diane Papan wanted to get more public input before making any changes, citing previous meetings before the pandemic when the council promised more outreach.

“I know we all want to do this, but I think we should get some more public input like we promised to do, so we get it done right,” Papan said.

Mayor Eric Rodriguez also wanted more community input and did not want to rush into an ordinance. He did not want changes without getting more public feedback, and he favored a detailed public process like Redwood City.

“But before we change ordinances without community input, I think we need to take a more conservative approach,” Rodriguez said.

The ordinance change passed 4-1, with Rodriguez voting against it. The ordinance will be formally adopted at the April 5 meeting.

curtis@smdailyjournal.com

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