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  • Lorianna Kastrop

Accessory Dwelling Units:  The changes to California state law that you need to know

By Lorianna Kastrop, Vice President, The Kastrop Group, Inc. Architects

The Bay Area is experiencing a housing availability crisis and demand for residential units near work centers has skyrocketed. Everyone knows this, and finally there is an option available to relieve some of the pressure. SB 1069 was signed into law by Gov. Jerry Brown last year. Introduced by State Senator Bob Wieckowski (D-Fremont), the bill amends the CA state building code for accessory dwelling units (also known as in-law units, granny flats, or secondary dwelling units). It eases the restrictions on building a second unit on residential properties, either attached or detached. The legislation is supported by the Bay Area Council, the AARP, the California Teachers Association, and a variety of housing and environmental groups.


A detached Accessory Dwelling Unit above a home’s garage that The Kastrop Group, Inc. Architects recently completed in Redwood City. Click here for more photos and a narrative available on our website. Photo Credit: Roger Dettloff

Here is a summary of the SB 1069 code changes and some advice to alleviate possible negative impacts of the changes:

  1. Provides exceptions to certain parking restrictions. Basically, if your home is located within a half-mile of public transit, you may be exempt from adding another parking space for the ADU. This could be a train station, BART station, bus stop, park-and-ride location, etc. There is also flexibility if you are in a designated historic district. Advice: To be a good neighbor, if you build an ADU, please encourage the occupant(s) to make use of public transit/bike/ride sharing instead of squeezing another parked car onto the street in your neighborhood.

  1. Eases sprinkler requirements that would be triggered by the addition of an attached ADU. Advice: Be sure your home is equipped with up-to-date smoke/carbon monoxide alarms in as many rooms and living areas as possible. Have them wired in, or check the batteries in spring and fall. As a rule of thumb, replace batteries when Daylight Savings Time starts and ends. Upgrade your electrical panel as necessary to accommodate the heavier load placed by the ADU. Don’t overload outlets with too many devices, and be careful with any open flames or candles.

  1. Makes utility connection fees for new construction proportionate to the burden that the ADU will place on the existing water or sewer systems. Advice: Install low-flow toilets, showerheads and faucets. Use a grey-water or smart-system for irrigation. Be thoughtful about anything you put down the drain or in the toilet. Don’t overload or clog the sewer system.

  1. Requires “ministerial” approval for remodeling existing homes or garages if they are compliant with building and safety codes. Advice: The trick to this is to check City/County records to be sure that all construction on your home, including any additions and improvements, were permitted. Any do-it-yourself additions done without a permit will be revealed if you start the ADU permit process and will hold up your permit. Be proactive and have your architect who is working on the ADU include any legalization issues that need to be addressed as part of your project.

Item #4 has also, in practice, relaxed some of the development standards for ADU’s. These may not apply in every case, but here are some examples.

Depending on the height of the ADU, the rear and side setbacks from the property line could be as little as five feet. Advice: Consider what is on the other side of the fence when you design the ADU. Try not to place a window in a spot that makes your neighbor feel that their privacy is affected.

May increase the potential floor area of a detached second unit. Advice: Check your local ordinances. Be sure that the total floor area for the primary and the secondary units combined does not exceed the maximum floor area allowed within the zoning district for the parcel. It’s also a good idea to increase your insurance coverage for the ADU based on the additional square footage.

Height restrictions have also been relaxed somewhat, but second floor balconies, decks, and windows are still subject to a variety of restrictions. Advice: Again, check local ordinances and be considerate of your neighbors.

The above general descriptions are summaries and will not apply to every property. Your existing city/county ordinances have much more detail. For the County of San Mateo, here is a link to the document:

Maybe you are planning for multi-generational housing to accommodate your grown children or your parents. You may be figuring out how to offset your mortgage costs by creating a rental unit on your property. These new rules will be of great help to you and will eventually expand the availability of residential housing units in California. Talk to your local licensed architect about what your options are. Excellent sites to search for architects are or

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