We have been seeing them pop up in residential backyards all over town. Stand-alone cottages, two-story cottages, or apartments over garages. What is going on?

Our city has a lack of urban affordable housing. With a job growth rate of almost 175,000 job since 2010 (seattlebusinessmagazine.com) in the Seattle City area, employees want to be close to their place of employment with or without the need for a car. Our City Council member, Mike O’Brien, has introduced a proposal to make it easier for homeowners to build cottages (or Detached Accessory Dwelling Units-DADU) on their property for various uses.

According to the Seattle Department of Planning, the definition of a DADU follows:

“An accessory dwelling unit or detached accessory dwelling unit (sometimes called a mother-in-law apartment) is a separate living space within a house or on the same property as an existing house. A legally permitted unit on the property (but not within the home) is called a backyard cottage or detached accessory dwelling unit (DADU). The property owner must live in either the house or the attached or detached accessory dwelling unit. Tiny houses, with foundations, are considered DADUs.”


Currently, a designated parking space on the property for a DADU is required unless you are located in designated urban villages and urban centers or in low-rise zones. Additionally, the property owner must live in the main home at least six months out of the year.

Among other guidelines, these two rules would change in the new proposal. No off-street parking space would be required for a single-family lot within urban villages or urban centers. This change has been proposed to stop the unnecessary removal of green space within the city. Further, the property owners would be able to lease their main home in addition to the DADU lease if they have lived in it for at least one year after the DADU was completed.

DADUs or cottages have many uses. Homeowners can use them to house in-home child care professionals or as a dedicated office space. Other uses are caregiver quarters for aging homeowners or their loved ones or as extra space for older children and their families when they come for a visit. Cottages can also be used as a short or long term rental space and provide homeowners with additional income.

What Homeowners should know:

1. DADUs are a big selling point for homeowners in the Seattle area so it is worth the investment. Buyers like the flexibility it provides them for future uses.

2. If you are considering building a DADU, go to the Seattle DPD website and research the current requirements and know what you are getting into.

3. If you are concerned about neighbors building a DADU, go to the Seattle DPD website and search property records to see if permits have been obtained for such a project.

4. Familiarize yourself with the changes proposed by Mike O’Brien to our current legislation. It may be worth waiting to see if these changes will be implemented if you have an interest in building a DADU.