San Mateo council needs more time for decision on ADU rules

Following council input Feb. 22, city staff is making changes for council approval March 7. Changes include a height limit for attached ADUs of around 24 feet to the top plateline and 32 feet to the roof peak, while the detached ADU height limit is 16 feet to the top plateline and 24 feet to the roof peak. A plateline is the point where the top of the wall assembly meets the roof structure. The changes will allow for detached ADUs to increase their height limit when built over an existing detached garage or if additional setbacks and an off-street parking space are provided. The council was initially considering height options of 16 to 24 feet and 20 to 28 feet for attached ADUs. The council will also be the final decision maker on an ADU appeal under the alternative discretionary review process.

ADUs are detached independent units and are sometimes called second or granny units. People can use ADUs to accommodate older family members or young adults fresh out of school, adding additional income or maximizing unused space. The city hopes to use them as housing units to meet state requirements. The city held several study sessions and meetings in 2021 to try and hammer out details, with the most recent council meeting in September.

The city’s proposed ordinance will require JADUs to be a maximum of 650 square feet. It will eliminate the owner-occupancy requirement for ADUs after 2024 and include ADU construction incentives that exceed the city’s reach codes. The ordinance will let a lot’s remaining floor area allowance determine an ADU’s size rather than establishing a maximum size limit.

Mayor Rick Bonilla was one councilmember who pushed for fewer restrictions on heights and size with the flexibility to have higher height limits.

“Much like the situation we discussed with SB 9, we have a law, and it says we must allow these,” Bonilla said.

The city is updating its code to meet state ADU legislation that went into effect in 2020. The law creates minimum standards that supersede local ordinances. In 2021, there were 83 applications for ADUs, with 66 permit issues. There were 47 permits issued for 91 applications in 2020 and 44 permits for 56 applications in 2019.

Councilmember Joe Goethals said his initial worry about an avalanche of ADUs in neighborhoods was unfounded, given the relatively low number of applications. He was comfortable with higher heights, given many people are using ADUs to house family members or pay mortgages.

“If that’s what they are being used for, and that’s what I see, and that’s what everyone who has talked to me about these tells me they are being used for, I think it’s something we should support,” Goethals said.

Deputy Mayor Diane Papan favored keeping a detached ADU have a height limit of 16 feet by 24 feet. She compromised by offering that detached ADUs height limit be increased when built over an existing detached garage.

“When I look at what other jurisdictions have done, I think we would be pretty in line with what is going on in our community,” Papan said.

Councilmember Eric Rodriguez advocated for smaller ADU sizes and height limits instead of maximizing height. He wanted to keep daylight plane restrictions, which ensure air and light are provided between neighboring structures to prevent constant shadow in the surrounding areas. He favored discretion and keeping detached ADU height limits at 16 by 24 feet.

“We need to move here with caution. The reason we are having this discussion is the state changed a law and made us clarify it, but that doesn’t mean we need to increase our longstanding ADU ordinances because of this new law,” Rodriguez said. “It doesn’t require us to go bigger.”

curtis@smdailyjournal.com

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