A Tour of East Bay ADUs

As more states and localities legalize the construction of Accessory Dwelling Units (ADUs) on single-family lots, Kol Peterson describes some examples of ADUs in Northern California's East Bay, where relaxed regulations have led to a growth in ADU construction. But despite upzoning initiatives, Peterson writes, "detached ADUs are encumbered by Title 24 with the same standards and requirements as are used for large detached homes, including glazing requirements and appliances such as water heaters."

According to research from Karen Chappel at the University of California Berkeley’s School of Environmental Design, informal ADUs already make up 17 percent of housing stock in the East Bay, signaling a strong need for legalizing and regulating this housing type to ensure safety while allowing property owners to maximize their density and provide a key element of 'missing middle housing.' Peterson tours a variety of formal and informal ADUs in communities around the region, from custom designs to prefabricated ADUs and affordable units that cost just $60,000 to build. 

While upzoning for ADUs and other 'mid-density' housing types has become an increasingly popular policy tool for encouraging denser housing development, experts caution that addressing density restrictions alone won't necessarily create more housing if other regulations and local opposition make construction expensive and cumbersome for developers and homeowners.