According to the Seattle Municipal Code, the City of Seattle has a Department of Construction and Land Use and maybe they could answer your question. (SMC 3.06.070)
The City of Seattle website, on the other hand, indicates the Department of Planning and Development might be your best bet. (http://www.seattle.gov/dclu/default.asp).
[In accordance with the Avvo community guidelines, this communication does not constitute "legal advice", nor does it form an attorney-client relationship.]