Zoning Changes Would Mean More Granny Flats and Fewer McMansions in Seattle

Is this a two-birds-with-one-stone situation?

2 minute read

May 30, 2019, 9:00 AM PDT

By James Brasuell @CasualBrasuell


McMAnsion

Rigucci / Shutterstock

The Seattle City Council is considering a new ordinance that would ban the construction of large, detached single-family houses (more commonly referred to as McMansions) while also easing restrictions on accessory dwelling units (i.e., ADUs, but also commonly referred to as mother-in-law units of granny flats).

City Councilmember Mike O’Brien is championing the potentially game changing legislation, according to an article by Daniel Beekman. Mcmansions are a particularly popular building typology in Seattle these days, like in many other cities. "O’Brien’s proposed limit would have blocked almost half the new single-family houses constructed in Seattle since 2010, had it been on the books," according to Beekman.

As Beekman explains, the bill's dual purposes are the results of a political calculus intended to broker a partnership between two usually opposing forces: pro-development YIMBYs and anti-development homeowners (sometimes referred to as NIMBYs).

"O’Brien has described backyard cottages and basement apartments as a gentle way to add density as Seattle’s population grows, knowing he can count on urbanists as cheerleaders. By taking aim at McMansions, he hopes to also win support from residents grumpy about development."

According to Beekman, the proposal's less restrictive regulations of ADUs have gained more attention than the more restrictive regulations of McMansions.

As for the key matter of how the city's zoning code change would change to restrict the development of McMansions, Beekman provides the following explanation: "Under O’Brien’s legislation […] the city would adopt a maximum Floor Area Ratio (FAR) of 0.5 for new houses on most lots."

While the city considers these substantial changes to its zoning code and the types of single-family housing it will allow in the future, the Washington State Legislature recently approved legislation that would provide incentives for local governments to increase density.

Wednesday, May 29, 2019 in The Seattle Times

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Get top-rated, practical training

Concrete Brutalism building with slanted walls and light visible through an atrium.

What ‘The Brutalist’ Teaches Us About Modern Cities

How architecture and urban landscapes reflect the trauma and dysfunction of the post-war experience.

February 28, 2025 - Justin Hollander

Complete Street

‘Complete Streets’ Webpage Deleted in Federal Purge

Basic resources and information on building bike lanes and sidewalks, formerly housed on the government’s Complete Streets website, are now gone.

February 27, 2025 - Streetsblog USA

Green electric Volkswagen van against a beach backdrop.

The VW Bus is Back — Now as an Electric Minivan

Volkswagen’s ID. Buzz reimagines its iconic Bus as a fully electric minivan, blending retro design with modern technology, a 231-mile range, and practical versatility to offer a stylish yet functional EV for the future.

March 3, 2025 - ABC 7 Eyewitness News

Blue train on coastal rail in Southern California.

SoCal Leaders Debate Moving Coastal Rail Line

Train tracks running along the Pacific Ocean are in danger from sea level rise, but residents are divided on how to fix the problem.

March 7 - The New York Times

Woman and two children sit on bench at public transit stop waiting for tram with stroller next to them.

Are Mobility Hubs Child-Friendly?

‘Mobility hubs’ aim to make urban travel easier by connecting travel modes. Adding more services could make them more accessible and useful to women and families.

March 7 - Streetsblog USA

Rendering of blue and white light rail train passing next to tree-shaded walkway with pedestrians in Austin, Texas.

Austin’s Project Connect Funding Safe for 2025

The light rail project is moving ahead with plans to finalize its environmental impact review by late 2025.

March 7 - Smart Cities Dive