Converting grandfathered duplex to SFH to add ADUs

[Eugenia K.]

There appear to be a handful of grandfathered duplexes with non-conforming AADUs on the market! I was wondering if people had experience with and/or perspectives on legalizing the 3rd unit by converting the duplex to a SFH (which then would have 2 AADUs)?

Wondering how this might impact:

- Appreciation and buyer desirability 

- Financing (after buying with a 2-4plex interest rate initially)

- Cost to legalize

Example listing: https://www.redfin.com/WA/Seat...