SB-9 graphic

A graphic illustrates how opponents of Senate Bill 9 believe the new law might affect future housing density in California.

By allowing duplexes on parcels in suburban neighborhoods, a new bill signed into law has eliminated “single-family zoning” in California, but the real-world impacts are projected to be modest.

Gov. Gavin Newsom signed two new housing reforms last week, Senate Bills 9 and 10, to make it easier to build more, denser housing in California. SB 9, which has the biggest projected impact on cities like Los Altos, permits lot splitting in single-family neighborhoods and duplex construction, including on each parcel on a split lot. SB 10 streamlines the approval process for multifamily housing of up to 10 units in urban areas near transit.

Supporters hope the bills will fuel new construction in a stymied housing market and that denser, smaller homes will help broaden access to neighborhoods with high home prices, particularly those formerly restricted by stringent development standards subject to local control.

The impact of the bills will include a potential for more single-family-home neighborhoods to see smaller houses on smaller lots with significantly smaller yards. How often those prospective new units will be built by current homeowners able to meet the substantial financial requirements of an eligible project remains an open question. An owner occupancy requirement written into the bill – aimed to prevent developers from buying parcels to split and redevelop – drew skepticism from critics like Los Altos Hills resident Barry Smith. He noted that only “intent to occupy” is required, a relatively toothless measure that will be difficult or impossible to enforce.

A landslide of new development is not anticipated by those studying the bills’ likely impacts. UC Berkeley’s Terner Center for Housing Innovation estimated that across the state, approximately 700,000 potential new housing units might become “market feasible” under the rules change. The study found that for the majority of eligible parcels, “the most financially viable outcome is not to pursue any development whatsoever,” with the most notable anticipated impact being allowance for more units in a prospective redevelopment. Subdividing an existing house might prove more economically practical than larger scope splits and new builds.

Los Altos resident Sue Russell, a housing advocate who has been following the progress of the bill, said the League of Women Voters, which endorsed SB 9, was likely to schedule an information session in partnership with Los Altos city staff to help residents make sense of how the rule change will work in practice when it goes into effect next year.

Supporters of SB 9 frame the move to state oversight as a long overdue mitigation of local policies that were used over the last century to advance antidevelopment policies with racist and classist impact on local residents.

Critics of the housing bills, who feel they removed valuable local ability to self-determine what gets built in a neighborhood, are mustering support for an upcoming ballot measure, “Californians for Community Planning,” which would amend the state constitution to return local control to land-use decisions such as zoning.



Eliza Ridgeway edits the Food & Wine, Camps, Bridal, Celebrations and Beyond the Classroom sections at the Town Crier, as well as reporting for all sections of the paper.