Changing a Duplex to a Triplex with the City of Seattle

[Devin Chong]

Hi All, 

I have been looking at a Triplex in Seattle very close to where I currently live that would allow the potential to house hack.  It is listed as a Triplex, however might be considered as a Duplex by the City of Seattle. Does anyone have experience changing a Duplex into a Triplex with the City? Is it a difficult process? Should I even bother?

I have inquired with the listing realtor about the property and here are the details: 

• We believe the property has been used as a 3-unit building since roughly 1953 (prior to the City of Seattle annexing the area).

• Unfortunately, it was not continuously used as a triplex (the triplex use was apparently interrupted in 1971), so it was established that it would not be grandfathered in and no longer be considered a legal triplex by the city (even though the County records designate it a triplex).

• Property records obtained from the City of Seattle Permit Center are available upon request

• It is currently considered a legal duplex by the city.

• After meeting with the City of Seattle Permit Center, it was found that there is a path to getting three rentable units without an owner occupancy requirement:

• The owner would need to file a building permit for a change of use.

In order qualify, the owner would have to do the following:

• Change the use to a SINGLE-FAMILY home with two accessory dwelling units ("ADU"). Duplexes are not allowed to have ADU's.

• Because of the age of the house, there are no restrictions to how large the ADU units can be. The current configuration of two units that are roughly the same size, and one smaller unit, is apparently OK.

• One of the ADU units must either be built to a high environmental standard OR must be reserved for low-income housing. The property would need to show that the units meet safety standards (ingress/egress, etc.), but we understand the paperwork is otherwise fairly simple.

▪ The review time is about 2-3 months once the application is submitted.

Any feedback or input is appreciated. 

[Devin Chong]

@Christian Nossum I agree, the process seems backwards! I just inquired with the permits office today for alternative options.  I will let you know if I find out anything else.