Examples of backyard in-law suites from New Avenue Homes

The San Francisco Board of Supervisors recently approved two significant pieces of legislation that support accessory dwelling units (ADUs), also known as “in-law” or secondary units, in the city. The first, introduced by District 3 Supervisor David Chiu and passed on April 17, enables existing illegal units to be legalized. The second, introduced by District 8 Supervisor Scott Wiener and passed on April 16, allows for the construction of new accessory dwellings in his district. These landmark legislations are huge steps for San Francisco, a city with a long history of unsuccessful attempts to pass such measures.

An accessory dwelling unit, as defined in a 2006 SPUR Housing Policy Report, is an “additional, self-contained dwelling unit located within the same lot as an existing residential building.” They’re often located in converted garages or in backyards as a separate structure. It is estimated that there are anywhere between 30,000 and 50,000 illegal accessory units in San Francisco — all built without obtaining the appropriate permits.

Historically, the city has adopted a “don’t ask, don’t tell” policy when dealing with accessory units, but many of these house lower-income and immigrant families, among others, who are threatened with eviction. In fact, approximately 100 such units are removed from the market each year, often due to complaints from neighbors.                       

The history of accessory dwellings goes back to the early 20th century when they were a common feature in single-family homes. Supporters say accessory units are a viable form of affordable housing with minimal impact on a neighborhood’s physical character, thus easily adding to San Francisco's housing supply. They are also accessible to elderly family members and the physically handicapped.

Opponents say these units add to parking congestion, impact the physical character of a neighborhood — particularly if that neighborhood is primarily single-family homes — and run the risk of attracting speculative investors that want to capitalizing on rising property values.

Despite these issues, Supervisors Chiu and Wiener each successfully passed their ordinances.

Supervisor Chiu’s legislation offers a way for property owners to bring illegal units up to code. However, they will also be allowed to ask city officials to “prescreen the units," and if the costs for upgrading the units are too much, they can drop out without penalty. In order to protect renters, the units will be covered by the city’s rent-control ordinance, so they could not be converted to condos. Although this particular measure does not increase the supply of housing in San Francisco, it does help maintain existing affordable housing.

While the legislation passed with an 8-2 vote at the Board of Supervisors, there was skepticism from certain parties. District 10 Supervisor Katy Tang said, “I don’t feel that property owners, despite the fact that this is a voluntary program, will want to take advantage of it.”

Supervisor Wiener’s legislation legalizes the construction of new accessory units in District 8, primarily the Castro neighborhood. Previously, new units could only be built if they were dedicated for seniors and built within certain zoning districts. It's a pilot program, as creating a new citywide program to build new units would have been too difficult to pass.

Under Wiener's legislation, developments with fewer than 10 units can add one accessory unit, while those with 10 or more can add two. These new units cannot be more than 750 square feet. The program is entirely voluntary, and if maximized, would create about 400 new homes. Units built within rent-controlled properties would also be subject to rent control. The legislation received unanimous support from the Board of Supervisors.

Using accessory units as a means of creating new housing is one recommendation in Shareable’s report, Policies for Shareable Cities. For the month of June, Shareable will be running a solutions-focused editorial series on the housing crisis in San Francisco and beyond in cooperation with San Francisco Public Press.

Make sure to attend the upcoming event on June 13, “Hack the Housing Crisis,” co-organized with the Public Press, for a look into innovative solutions for affordable housing. You can also share your thoughts using #HousingHack on Twitter.


This post is part of Shareable's and San Francisco Public Press' exploration of affordable housing solutions during June and July 2014. Check out the rest of the series here.




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Rob works at the San Francisco Housing Action Coalition (SFHAC), a small nonprofit that advocates for the creation of new housing for all levels of income in San Francisco.