Measure to reduce barriers to building ADUs in Seattle gets mayoral boost

Earlier this month, the Seattle City Council approved legislation that could make it easier to build accessory dwelling units (ADUs)—like backyard cottages and mother-in-law apartments—along with language that would rein in McMansions in single-family zones. Tuesday, Seattle Mayor Jenny Durkan signed the legislation, and tacked on an executive order directing city agencies to make building ADUs less costly and onerous.

The legislation itself gives more maximum square footage to ADUs to be larger (1,000 square feet), allows two on one lot instead of one, and axes a requirement for off-street parking, a sometimes complicated and expensive hurdle for homeowners to jump. It removes a requirement for owners to live on the lot where an ADU is constructed in order to rent it out.

The measure has more far-reaching implications, too: It sets the floor-area ratio (FAR) limit in single-family zones, which limits how much square footage a house can have in relation to its lot, to .5. For example, a single-story house could only have a footprint of half the lot, or a quarter for a two-story house with equal square footage.

Despite more flexibility with how ADUs are built, it can still be extremely costly and time-consuming to get one built. ADUs are still subject to city permitting, which adds to the price tag even before construction and utility costs come in.

Durkan signed the legislation itself, but added an executive order telling various city agencies that handle construction, building code, housing, and neighborhoods—the Seattle Department of Construction and Inspections (SDCI), the Office of Planning and Community Development (OPCD), the Department of Neighborhoods (DON), and the Office of Housing (OH)—to reduce economic and bureaucratic barriers for homeowners trying to build an ADU.

Among other things, the order directs city staffers to:

• Pre-approve some ADU plans to streamline the permitting process and implement shorter timelines for homeowners using those plans,
• Appoint a new city position dedicated to helping homeowners navigate the process,
• Build online tools for homeowners to get more clarity and explore feasibility,
• Convene an “ADU working group” with advocates and building professionals (like arborists and builders) to run programming for homeowners and make recommendations,
• Use an existing Home Repair Program to run a small-scale pilot to provide low-interest financing for ADU construction—especially ADUs that will become affordable housing, and
• Monitor ADU development trends and statistics, reiterating a part of the City Council ordinance that requires regular reports and adding participation in city programs to the mix.

Now that it has the mayor’s signature, the new ADU rules will go into place August 8, 2019.