Photo: An accessory dwelling unit above a garage in Portland, Oregon's Irvington neighborhood. Taken by Flickr user Radcliffe Dacanay, used under Creative Commons license.

Updated at 11:22 a.m.

A push began Friday to eliminate zoning rules that bar single-family homeowners from building an additional unit on their property, sometimes known as a "granny flat."

So-called accessory dwelling units are illegal in Minneapolis' single-family residential zones, outside of an area around Ventura Village established in 2001. Advocates say they are a more affordable addition to the city's housing stock, potentially accommodating extended families or more traditional renters.

“It’s ... another way to provide housing options within neighborhoods aside from multi-family buildings," said council member Lisa Bender, who on Friday will begin the process of debating the change. "So it’s a way to add smaller units within neighborhoods.”

The units are already popular in several other cities like Portland, Vancouver, Seattle and Austin. Cities regulate them in different ways, however, and Minneapolis will need to determine what kinds of units will be allowed.

"They can be a unit above a garage or a small carriage house built on the same lot," Bender said. "Some cities also allow them interior to the home, so like a basement or a third-floor apartment.”

That's part of what will be determined over a summer-long public engagement process. The city will hold two open houses on the plan in August, Bender said, with the formal council review beginning sometime in the fall.

Bender said that city staff have been receiving a number of questions about the units, indicating that there is a demand. “It’s a relatively affordable way to add another unit to the same lot," Bender said.

Supporters say the units add flexibility to the current single-family housing stock, much of which was built in an era when more people shared households. But they are not without controversy, as evidenced by a debate this spring in St. Paul's St. Anthony Park neighborhood.

Mayor Betsy Hodges and Council President Barb Johnson voiced support for the idea in a news release Friday morning. "As our city’s population grows, our neighborhoods are in high demand and allowing accessory dwellings is a great way to provide more housing choices to more people,” Hodges said in a statement.

Bender formally introduced the ordinance at a City Council meeting on Friday morning.

UPDATE: The dates of the public meetings have been released: The first open house will be held on Tuesday, Aug. 12 at the North Regional Library from 5-8 p.m. This will be followed by a second open house at the Hosmer Library on Saturday, Aug. 23 from 10 a.m.-1 p.m.