In other words you have to apply a layer of common sense as to whether what you want to do makes sense for where that duplex is. No one who owns a conforming single family home nearby would expect the City to give a variance for less than the SF5000 zoning allows. People rely on zoning as a support for their property value. But if most of the neighboring properties don't conform anyway and the City is targeting that area for revitalization via zoning variances, then it would make sense to be thinking along the lines that you are thinking.
Would two homes on less than 5,000 sf lots be an improvement to the block? If yes, then you have a strong maybe. If no, then don't get your hopes up. Check it out in either case, but your expectations of a yes or no answer should be set before you start spending money on getting that real answer. You can save yourself a lot of time and money if you apply common sense first.
At the moment, past history is not a good indicator, as Seattle is leaning away from being generous on this issue recently...vs 1 to 7 years ago. The wind has changed.
It sounds like your grandfathered with the duplex, but any new changes have to be done according to the SF5000 zoning rules at the DPD. Which says you won't be able to build 2 homes on one single family lot of your size.
Seattle Department of Planning and Development (DPD)
The Seattle Department of Planning and Development (DPD)
To clearly determine what you can do, you can go to the front desk and ask a them what the rules are or look at their website.
I have been in real estate and construction for over 25 years here in Seattle and have a vast knowledge of the codes, but always double check with them for any rule changes.
Your only reliable answer will come from the Seattle Department of Planning & Development. So often the "rules" as stated get waived, amended or have variances granted due to other circumstances that even if you get a "yes" or "no" from someone here, I wouldn't take that as a final answer.
I've added a link to the City's site below. Let us know how it turns out.
What someone tells you "might" happen, isn't always what happens.
Your best bet is to schedule a sit-down with DPD. They charge you a fee for the meeting, but you'll have an opportunity to talk with a land-use specialist.
You can also submit specific questions to DPD via email, but you really need to know what to ask, or you will not get the answer you seek.
In my opinion, having a duplex in a single-family zone may be more desirable than demolishing it and replacing it with one new single-family home. Good luck with your decision.
codes. I would have references for you if you would like to contact me, Mike Knutsen, John L Scott
KMS, Inc, 206-941-3300.
What you want to do is walk into the city of Seattle permit desk and ask your question. The person at the counter can pull up the zoning maps and can answer your basic questions. If, after the basic questions, your plan looks fruitful, you can set an appointment with a higher level planner., or maybe even talk to one when your there.
The next step, if your plan still looks good, is to set up a "pre-development" meeting or building feasibility meeting.
None of us can answer your question without specific location and without looking into the detailed requirements for your zoning code.