Seattle Homeowners Have Option to Build Accessory Dwelling Units

Love it or hate it, a dramatic shift in the Seattle Building Code for single-family residential property owners has been signed by Mayor Durkan. On July 1, 2019 Seattle passed one of the most aggressive housing bills in the country, Council Bill 119544. In an effort to accommodate Seattle’s growing population, this bill allows for greater density by allowing the construction of up to two Accessory Dwelling Units (ADUs) in all single-family zoning. It also limits the construction of larger homes to varying degrees. Quite a lot is changing, and I am here to help clarify the changes.

Overall, the owner-occupancy and parking requirements for ADUs have been removed. A quite controversial move in and of itself.

If your home is zoned as SF5000, SF7200, and SF9600, the new permittable Floor Area Ratio (FAR) is 0.5, meaning a newly constructed homes can only be 50 percent of the lot size, (a new home on a 5,000 sf lot cannot be larger than 2,500 square feet – a significant reduction in what was permittable previously). The controversy is that property owners are permitted to add square footage, if it’s an ADU. New guidelines permit 2 ADUs at 1,000 sf each (one attached ADU and one detached ADU, at a maximum of 1,000 sf each.)

Further, property owners are also allowed to build an accessory structure, like a garage, up to 500 sf without it counting towards their FAR limit. Any square footage that does not extend more than 4 feet off the ground, underground or partially underground, would also not count against your FAR usage.

If your home is zoned RSL (residential small lot) the limits are like the above requirements, however, the FAR is 0.75, with only one Accessory Dwelling Unit.

If you want to further understand how this new legislation will affect your home, please reach out. I’m here to help.

Visit seattle.gov for more information about the bill.