In-law suites, granny flats, accessory dwelling units — whatever you call them, developers and housing economists say these units could be a cure to the inventory shortage in real-estate markets nationwide. That is, if homeowners actually show interest.
Accessory dwelling units are secondary units built on or into single-family homes. Most often they are completely separate, cottage-like structures, though in other cases, they are spaces that were converted from garages or basements to serve as an individual living quarter. In recent years, advocates have pushed city and state governments to loosen zoning laws so that more of these units can be built.
And those laws appear to be having a significant effect. In California, three new zoning laws took effect in 2017 that allowed for expanded development of granny flats. As a result, California experienced the largest uptick in the number of building permits granted for these units of any state, with a 63% increase, real-estate data firm Attom Data Solutions reported, using data from real-estate data provider BuildFax.
Some cities particularly benefited: Santa Barbara, for instance, saw 314% more permits issued for accessory dwelling units, or ADUs for short. Hawaii saw the next largest increase of any state at 31%, followed by Tennessee (25%) and Washington (22%). California also had the largest number of total permits issued in 2017 for in-law apartments, with 4,352, more than twice as many as Oregon, the state with next-most.