Newsom Signs McNerney’s Bill to Streamline Construction of ADUs

Gov. Gavin Newsom today signed Sen. Jerry’s McNerney’s SB 543, which will streamline the construction of accessory dwelling units (ADUs), also known as backyard cottages or casitas. 

SB 543 will also accelerate the construction of junior ADUs (JADUs), such as an attached garage or basement converted into living space.

“California needs to build housing to help make our state more affordable. And one of the most effective ways to address our housing affordability crisis is to accelerate the construction of low-cost housing, like ADUs and junior ADUs,” Sen. McNerney said. “Gov. Newsom’s signing of SB 543 will make it easier to build ADUs and junior ADUs and help California meet its goal of building over 2.5 million homes by 2031.”

SB 543 garnered unanimous support in the Legislature. The new law goes into effect Jan. 1. SB 543 is sponsored by the Casita Coalition.

“We’re grateful to Governor Newsom for signing SB 543. Casita Coalition was proud to sponsor this bill with Senator McNerney to ensure that lower-cost Junior ADUs have the same clear, consistent standards as ADUs —  making it easier for homeowners to build and for local agencies to implement,” said Noerena Limon, CEO of the Casita Coalition.

According to the Department of Housing and Community Development (HCD), California must build over 2.5 million homes by 2031, and at least 1 million of those homes need to be affordable for low- and very-low-income residents. Building more ADUs and JADUs can help the state meet its housing goals quicker, because they’re cheaper and faster to construct. ADUs are detached units on residential property, while JADUs are attached to a home, such as an attached garage or basement converted into living space.

A decade ago, California was permitting only about 800 ADUs per year. But now, thanks to a series of new ADU laws passed by the Legislature, California is permitting about 25,000 new ADUs and JADUs each year. Nearly one in four new homes in the state is an ADU or JADU.

However, some of California’s recently enacted laws contain provisions that have led to confusion and conflicts among some cities and counties. HCD has circulated guidance on these provisions in an effort to ensure the statutes are applied consistently across municipalities. Yet some local agencies have rejected HCD’s interpretations in favor of their own, resulting in conflicts over permitting timelines and other aspects of the homebuilding process. According to HCD, over 50 local governments have incorrectly applied state laws for ADUs and JADUs. 

SB 543 clarifies existing state laws governing ADUs and JADUs to eliminate confusion and conflicts at the local level. SB 543 codifies multiple HCD permitting guidelines, including clarifying:

• That local governments have 15 business days to conduct an initial review of ADU and JADU permit applications, so homebuilders have time to fix errors in their application.
• Size standards for ADUs and JADUs.
• That permitting guidelines for JADUs are the same as for ADUs.

Sen. Jerry McNerney is chair of the Senate Revenue and Taxation Committee and his 5th Senate District includes all of San Joaquin County and Alameda County’s Tri-Valley.