Hello, I just purchased an old home on Beacon Hill in Seattle that I believe is SF5000 zoning. Directly across the street from me has different zoning because there are a ton of duplexes and townhomes. Am i able to build a one structure duplex/triplex if the space permits for it? Any suggestions on where to start as this is my first home purchase.
Seattle SF5000 zoning means a single family home. currently a single ADU (detached or attached) is allowed subject to site conditions, etc. but there is a push to allow one attached and one detached unit, again subject to site conditions. However, in both cases it will be likely that the current owner-occupied requirement will be retained (owner must occupy one of the units)
Look at the proposed HALA upzone zoning map changes. they might affect your home especially if it is already adjacent to a denser zoned area.
If the home has a verifiable history of use as a duplex it may be grandfathered legal. Most likely it would be obvious - two electric meters, two mailboxes, etc, and might already reflect that use on county records. For example my triplex is in SF5000 zoning but was built when that area was LDT zoned, and is grandfathered legal for that reason.
Brian is correct. Unless something has been grandfathered in as part of the zoning, you would likely need to petition for a change in the zoning. The idea with your zoning currently is to allow only 1 dwelling unit per 5000 sq ft, with the few exceptions that Brian mentioned above, and with all of the proper setbacks. It can also depend on the size of the lot. If your parcel is 10,000 sq ft or greater, you may have an easier time with your proposed plan, but hey, it's Seattle...