Seattle’s long march toward easing the rules for adding new so-called mother-in-law style apartments and backyard cottages and apartments to single-family home properties will take big steps forward Tuesday as a Seattle City Council committee shapes final tweaks to plans some four years in the making.

City analysis shows only 1% of the approximately 124,000 single-family zoned lots in Seattle in use for single family residential development have added attached or detached “accessory dwelling unit” structures. There is room to grow.

After having the path cleared by the Seattle Hearing Examiner this spring, the proposals including allowing larger ADU structures, reducing lot size requirements, and eliminating costly barriers like required parking are getting their final updates and additions before going to the full council — hopefully in July.

PLEASE HELP KEEP CHS PAYWALL-FREE!
Subscribe to CHS to help us pay writers and photographers to cover the neighborhood. CHS is a pay what you can community news site with no required sign-in or paywall. Become a subscriber to help us cover the neighborhood for as little as $5 a month.

Possible amendments to be discussed Tuesday include a proposed prohibition on short-term, AirBnb-style rentals for ADUs and the lifting of duration requirements for ownership of the properties that was originally inserted to stave off concerns about predatory developers. Another amendment would open up amnesty for units created without permits prior to the new legislation.

The proposal will also break some new ground including allowing Seattle parcels to be home to up to ADUs and, sorry anti-growth NIMBY types, the limit on unrelated people residing on the property will be upped from eight to twelve.

To encourage ADU development, the legislation will also limit the allowed size of new houses in Seattle but with an interesting hook — ADUs won’t count against the cap. That provision gives developers “the option to make up for the capped house size by adding in-law apartments or separate cottages,” pro-growth and affordability nonprofit Sightline writes. “The result: smaller homes, and more of them per lot—a win-win for affordability.”

Seattle spent decades limiting the growth of ADUs. Creation of the units was more common in Seattle up until the 1950s when the construction was restricted throughout the city. In the ’90s, concerns about insufficient affordable housing stock led local lawmakers to reintroduce ADUs. It wasn’t until 2006 when the council passed an ordinance allowing single family homeowners in the southeast to build the units as a pilot project that backyard cottages were reintroduced. Four years later, in 2010, the council allowed for construction citywide.

Backyard cottages were still highly controlled in the years following the citywide expansion, however, and concerns about over-regulation stifling detached ADU construction prompted the city council to look into code changes in 2014. A city report (PDF) published the following year revealed that only 200 of the units had been permitted or constructed despite widespread availability of single family lots eligible for ADUs (around the 60% of all single family lots in the city), and identified regulatory restrictions on height, lot area coverage, and requirements like having (or building) one off-street parking space for a new ADU and the owner occupancy requirement—which mandates that the owner of a DADU either live in the cottage or in the adjacent single family home—as the main culprits behind low figure. Solicited public input (PDF) from ADU owners and potential owners and designers revealed similar sentiments.

How the new units will impact Seattle’s rental crisis isn’t known. Another amendment proposes that the plan to loosen the development rules should also include an attempt to answer the affordability question. The amendment proposes that the city’s planning department include a report on ADU permit activity and “the demographics of ADU owners and occupants, as well as the rent charged to ADU tenants.”