In 2019, the City of Seattle changed its regulations regarding accessory dwelling units (ADU’s), easing the construction of the “mother-in-law” or “granny-flat” buildings. The idea was to add badly-needed housing density in areas dominated by single family homes. Well…the concept is apparently working very well.

According to the Seattle Times, almost 1,000 ADU’s were permitted in 2022, a 250% increase since 2019 and the 650 ADU’s that were built outpaced the construction of single family homes for the first time. The type of people that are building ADU’s range from homeowners with aging parents, to couple’s who want rental income to developers testing a new market.

The regulation changes made in 2019 that are spurring the construction of ADU’s include allowing two per lot, no longer requiring property owners to live on site, no longer requiring off-street parking and allowing the ADU’s to be larger, taller and on smaller lots than before. 

The vast majority of new ADU’s are being permitted in Seattle regions that don’t allow multifamily construction. Popular ADU construction areas include Greenwood, Northgate, Ravenna and the Central area.