Two east metro cities will allow accessory dwelling units (ADUs), also known as "mother-in-law apartments," within their city limits this month, joining dozens of cities across the state.

The New Brighton City Council approved an ADU ordinance Tuesday and the Falcon Heights City Council approved its ordinance Sept. 11.

Advocates of accessory dwellings say that amid a housing crisis, the units are a way to add "gentle density" to cities. More than 230 such units have been permitted in the Twin Cities metro since 2016, according to Metropolitan Council data.

This year, a bill that would have required cities across Minnesota to allow ADUs failed at the Legislature. But several cities have passed their own ordinances in recent months, including Edina, Vadnais Heights, St. Cloud, and now Falcon Heights and New Brighton.

Falcon Heights City Planner Hannah Lynch said she had received calls from residents and people seeking to move to Falcon Heights asking about ADUs. She said most residents expressing interest wanted options to house family members. Accessory dwellings will now be allowed on lots with single-family houses, provided the plans meet size, setback and other requirements, Lynch said.

Ben Gozola, New Brighton's assistant director of community assets and development, said in an email that the new ADU ordinance, drafted after soliciting community input through surveys and public meetings, replace outdated "servants' quarters" regulations with modern ADU ones, giving residents options to age in place, house medical professionals caring for loved ones, create living space for young adults or make housing more affordable by renting the ADU or primary home.