MYNORTHWEST NEWS

Seattle council approves ‘McMansion’ ban, backyard cottage proposal

Jul 1, 2019, 8:09 AM | Updated: 5:08 pm

Seattle is set to embark on a new frontier filled with backyard cottages, after Seattle City Council voted unanimously to approve a new measure Monday afternoon.

The bill expands the ability of homeowners looking to build backyard cottages and mother-in-law units. Supporters have argued that by allowing more small cottages — aka accessory dwelling units (ADU) — homeowners with adequate space could add more housing to the city, one backyard at a time.

“This legislation creates modest but meaningful changes to provide flexible, affordable housing options for families, homeowners, and renters while still preserving the look and feel of single-family neighborhoods,” said Councilmember Mike O’Brien, who spearheaded the legislation.

NIMBY, YIMBY, or classism in Seattle
Affordable housing slated for Seattle light rail stations

Opening up ADU potential in Seattle is only part of a bill that’s been almost four years in the making. It modifies a range of property regulations with the goal of creating more living space in a city desperately in need of housing. The proposal would:

  • Increase the allowable size of ADUs from 800 to 1,000 square feet.
  • Allow ADUs to be built on smaller lots.
  • Both backyard cottages and mother-in-law units could be built on the same property.
  • An owner occupancy requirement would be lifted. Previously, homeowners were required to live on site if they wished to rent on the property.

“Seattle is in the midst of an affordability and housing crisis,” said Seattle Mayor Jenny Durkan in a news release. “This crisis calls on each of us to act with urgency, using every tool available to increase housing options and make room for our neighbors as quickly as possible. Today, the Seattle City Council took an important step with the passage of this legislation, but there is more work to do.”

The council bill also goes beyond allowing for a new form of housing and bans another. “McMansions,” or considerably large homes compared to the property they occupy, are banned in the legislation. The square footage of new homes will be limited in relation to the lot size.

The proposed regulations would take effect six months after its passing, so there will still be a little bit of time to build a home so large and imposing that your new neighbors will be perpetually annoyed with you.

Backyard cottages

Seattle currently has less than 2,000 ADUs. The city estimates that the new regulations could open up a cottage industry over the next 10 years, bringing the total up to about 4,400.

The effort to open up Seattle’s regulations to allow for more backyard cottages and ADUs has been years in the making. The most recent effort was spearheaded by Councilmember Mike O’Brien in 2016. At the time, it was estimated that about 75,000 single-family lots in Seattle could qualify for backyard cottages. Following a study and an ADU pilot, Seattle was ready to open it up across the city — that is, after yet another study to look into the environmental impacts.

Then, the Queen Anne Community Council challenged the plan, arguing backyard cottages would negatively impact neighborhoods. That argument went to a hearing examiner which ruled in favor of the city in May.

Seattle Mayor Jenny Durkan also jumped on the ADU bandwagon in May 2018. The mayor proposed a streamlined approach to getting the cottages approved and built. The mayor’s plan is to pre-approve a range of ADU models which would go through less city paperwork, speeding up the permitting process.

MyNorthwest News

_spokane wildfires...

Luke Duecy

Convicted felon arrested in connection with Old Trails Fire in Spokane

Governor Bob Ferguson said federal resources are on the way to help Washington battle 17 major wildfires burning more than 260,000 acres.

8 hours ago

pierce transit (1)...

Nate Connors

Chill out during this week’s heat wave courtesy of Pierce Transit

It's become a regular service to Pierce County residents during the excessive heat bursts we often get throughout our summer season.

10 hours ago

Gifford Pinchot National Forest (1)...

Julia Dallas

Gifford Pinchot National Forest issues emergency closures for wildfire

The Gifford Pinchot National Forest has issued an emergency closure order for the High Lava Fire.

10 hours ago

washington...

James Lynch

Crime drops across every major category in Washington, but officials warn the full picture is more complicated

Crime declined across every major category in Washington in 2025, with sharp drops in murders, violent crime, and property crime.

11 hours ago

seattle homelessness...

Frank Lenzi

Seattle, King County plan to reclaim nearly $160M in homelessness contracts from KCRHA

The King County Regional Homelessness Authority (KCRHA) will survive despite calls from some Seattle and King County leaders to dissolve it.

12 hours ago

King County Metro...

KIRO 7 News Staff

King County Metro to add 9 new bus routes and 3,000 additional weekly bus trips to schedule

King County Metro is adding nine new bus routes and more than 3,000 additional weekly bus trips to its schedule.

12 hours ago

Seattle council approves ‘McMansion’ ban, backyard cottage proposal