How to add a second unit address for my ADU?
August 29, 2019 4:36 PM   Subscribe

We purchased a house with an established accessory dwelling unit in Seattle. However, it seems to not have a separate address. How can we get it registered as a separate unit number address?

I've hunted all over the city's website. I've delved the depths of every resource the USPS has online. I've trawled landlord forums. I've played phone tag with half a dozen city employees. I've battled the USPS's deeply unhelpful automated phone system. I still cannot find the answer to this question.

Here's the situation. We bought a house with completely separate ADU unit in the lower floor. We live in the upper floor. This ADU was permitted and constructed by the previous owner and we've registered it as a rental unit with the city's RRIO system, so as far as I can tell it's legit. However, the previous owner just had family living in the ADU so the whole house only had one address. We were expecting to just put up two adjacent mailboxes and have our section be 123 Fake St and the tenants be 123 Fake St Unit B.

However, it seems like they may be having issues getting Unit B mail to show up. How can we fix this? Is there some process to register new unit number addresses? Is this a city issue or a USPS issue?

This is specific to Seattle, but input from people that have navigated this situation in other cities is also appreciated.
posted by cirrostratus to Law & Government (11 answers total) 3 users marked this as a favorite
I built an ADU on my property a few years ago and, like you, was not able to find any information as to how to get it an official address. Let's say that my home address is 123 Main St. I installed a second mailbox with "123 1/2" painted on it, told my tenants that their new address is 123 1/2 Main St., and that's worked out just fine ever since. They receive letters and packages without any issue. My postal carrier did once have to ask me where the "1/2" address was, as it's not visible from the street, but that's the only question that I've had about it related to mail.
posted by mezzanayne at 5:00 PM on August 29, 2019 [1 favorite]

Have you gone to your local post office in person? In a very different context, I lived in a newly constructed house, and the post office wouldn't deliver until we registered that address at the local post office. I think you can probably solve this if you actually go to the closest local brick-and-mortar office.

You might also try exploring the local 911 information. Do they have this separate residence on file?

You need to register a new property, essentially.
posted by bluedaisy at 5:02 PM on August 29, 2019 [2 favorites]

Here we go: try calling or visiting the Seattle USPS office that works with their Address Management System. You can search for their information online, but it's here:

34301 9TH AVE S STE 249
FEDERAL WAY WA 98003-7089

Phone : (253) 214-1765
Fax : (253) 214-1822
posted by bluedaisy at 5:07 PM on August 29, 2019 [2 favorites]

Sorry this doesn't answer the question, but I'd like to advise not to use 1/2. I lived in a lower level ADU with a 1/2 address for a couple of years and the address was rejected by many online form validations. Unit B or 2 is definitely better. (Anyway, following, because we want to build an ADU in Seattle in the next few years.)
posted by matildaben at 6:08 PM on August 29, 2019 [1 favorite]

I'm not in Seattle, but we have an apartment that is behind our garage, which used to be labelled 4335 unit #1 or something, and the post office assigned it its own number, so it's now 4337. But my recollection was that the process was less bureaucratic than I would've expected.

When you said it seems like they may be having issues getting Unit B mail to show up does that mean you tried just putting up another mailbox for 123 Unit B and it's not getting mail delivered correctly?
posted by leahwrenn at 6:09 PM on August 29, 2019

It may be a city issue if the city is the water utility and the ADU has its own meter. If that's the case, the ADU might already have an address as far as the city is concerned. In San Diego, "addressing" was a city service that one could get at their building department (actual title: Development Services), but I don't know if that was more intended for full developments that were creating multiple addresses out of thin air vs. granny flats.
posted by LionIndex at 6:39 PM on August 29, 2019

We have a 3 unit building and just randomly decided which unit was A, B, and C, and then clearly labeled mailboxes. I doubt you'd have a problem if you put something up for Unit B next to your current mailbox.
posted by slidell at 7:42 PM on August 29, 2019

where I live I had to go to the local roads and bridges dept to get my mil apartment a separate address

I think the postmaster told me to do that
posted by cda at 10:47 PM on August 29, 2019

I recall a Twitter thread from a Seattle homeowner trying to do the same thing. He eventually posted this tweet linking to a city "tip" publication. There's a form at the end of that PDF that is apparently what you're supposed to give to the city.

I suppose you could contact the guy on Twitter as well, since he's apparently gone through the same thing as you.
posted by five toed sloth at 8:35 AM on August 30, 2019

For what it's worth, bluedaisy's link to the USPS address management system was productive. I had called that number weeks ago and got an unhelpful person that sent me in the wrong direction, but after calling again today they claimed they're adding the unit to the system within "2 weeks". So I should be all set on the USPS end.

As for the city end of things, I'm still not 100% sure if I'm all set or not. The "tip" pdf in five toed sloth's post seems to be roughly what I need, but once again actually trying to contact anyone related to that department has been ineffective. I may need to go to civic tower in person.
posted by cirrostratus at 2:59 PM on August 30, 2019

The key thing here has been persistence. Calling the same number multiple times until eventually I get someone that actually knows how to help has been the only way anything has gotten done here.
posted by cirrostratus at 3:01 PM on August 30, 2019

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