Governing---a national magazine and web site that covers state and local policy and politics---came to Seattle recently to cover the city's experience with detached accessory dwelling units, better known to you and me as cottage housing.

Seattle started allowing backyard cottages on certain single-family lots in Southeast Seattle in 2006, and expanded the program citywide in 2009. Since then, the city has issued 57 permits for cottage housing.

The magazine deems the experiment, basically, a success. Although some neighbors have expressed concerns about privacy and the character of Seattle's single-family neighborhoods, the story goes on to note that

after the city’s three-year experiment with ADUs in the southeast part of town, [Seattle urban planning supervisor] Mike Podowski’s office conducted a survey of residents living near a permitted backyard cottage to gauge the impact the units had on neighborhoods. What the city found was something of a surprise. Eighty-four percent of the respondents said the ADUs hadn’t had any discernible impact on parking or traffic. What’s more, most people didn’t even know they lived near an ADU, says Podowski. “More than half of them didn’t even realize there was a unit next door. It really helped us to show that a lot of the fears people had about these were not going to be realized.”

That positive feedback helped encourage the city to expand ADU zoning citywide. Council members also eliminated a cap on the number of backyard cottages that could be built in the city, and they rejected a proposed “dispersion” requirement, which would have limited the number of ADUs in a given neighborhood. The city prepared a design guide for homeowners, tips on being a good landlord and ideas for how to best respect neighbors’ privacy. Since then, the 57 new permits for backyard cottages number “in the ballpark” of what the city had predicted, says Podowski, and they’re evenly spread in neighborhoods across Seattle.

The city council's committee on the built environment will review the results of Seattle's backyard cottage legislation over the past two years at noon on Thursday, May 12, in city council chambers.