San Jose Town Hall

Introduction to ADU Zoning

Is your property zoned for an ADU? Learn all about zoning in California.





In California, like most American cities, you can see zoning in action by what isn’t being built and where. Zoning is a simple concept where rules, restrictions, and goals are defined for a geographical area. Zoning laws permit or prevent building in a specific location, depending on different project variables. In your own community you might see examples of zoning when you travel from a downtown core area with vibrant nightlife and businesses to a quieter residential area with progressively less density. Each zone is different, and often cities have multiple zones for the same category. For instance, some residential zones may have a different density and lot size requirement than in another residential part of town.



Zoning is a challenge for many homeowners because it prevents people from moving forward easily on their projects, or a rezoning leaves members of the community out during the process. It can often also be confusing!



Are you interested in building an ADU on your property? Check your Zoning Status here to see if your zone is eligible for an ADU.

While growth in California has slowed for the first time in over a century as a result of an increasingly educated population and shifting immigration patterns, the housing market has not come close to meeting the demand. And although California is relatively young compared to other US states, 1 in 5 individuals will be over 65 by 2030. A diverse set of consumers are seeking new housing solutions, from families looking to house their aging parents closer to home to short term renters looking for a getaway.



Development in affordable neighborhoods has slowed due to a lack of financial incentives for major developers. From shelters to church parking lots, communities have grown to find creative accommodations for the population experiencing homelessness. For example, San Jose pioneered a tiny home community to house some of its homeless residents. Quite simply put, California is in dire need of housing, and ADUs provide solutions for many of the states ailments.



With almost half of the United States in a similar position, many states are looking to modify their zoning regulations to make density and new construction more desirable. California is in the middle of this crisis as the most populous city in the US, few Golden State’s cities are on track to meet the demand for housing of nearly 3.5 million housing units by 2025, falling short by half.



In light of the housing market challenges, the State of California passed new laws to make it easier to build accessory dwelling units (ADUs) in garages and backyard. As long as you live in California in a residential zoning area, there is a good chance you can construct an accessory dwelling unit. Find out by checking your eligibility to build an ADU here.



Zoning Risks

Zoning regulations consider home construction specifications, environmental considerations, commerce, and transportation. Many cities have overlay zones which delineate anything and everything from flood hazards to earthquake risks. It’s these overlay zones that get tricky when constructing an ADU in your backyard. Ignore the local zoning code at your own risk. If your site plans don’t take into account the local regulations around fire, earthquakes, and flooding, you run the risk of not being permitted and potentially leaving your new ADU vulnerable to emergency events.



Even more so, construction of an illegal ADU means that it cannot be assessed as part of home value, and can not be legally sold as part of a broader home sale. This would result in the loss of tens of thousands of dollars. It could also negatively affect projects in the future, when modifying the illegal unit, or having other construction done.



Housable's free ADU Property Check toolcan give you an initial idea of your zoning eligibility.



The Road Ahead



There are no guarantees that you will be able to build an ADU on your property, but it’s likely possible.



Chances are, if your home isn’t in a floodplain, your accessory dwelling unit can be constructed in your backyard without concern for flooding. Of course the specifics of each property apply. If your backyard is extremely sloped, if your home is in an earthquake hazard area, or if you have a river in your backyard, it’s possible that these overlay zones will apply. It doesn’t mean you can’t construct your granny-flat, it just means you’ll have to take extra precautions.



It is critical to pay close attention to zoning if you want to set your ADU project up for success. Doing your homework up front can save an enormous amount of pain and frustration down the line.



On a final note, zoning is a great opportunity to learn about the geography, history, and character of your neighborhood. Hopefully after reading this article, you feel more informed and a little less intimidated by the concept of zoning so that you can move forward with your own housing project! Happy building :)



Would you like to learn more about your property's zoning eligibility? Check out the free Housable ADU Property Check tool for an initial idea, and purchase the ADU Property Report for full confirmation.