Wash. Rev. Code § 70.92.160
The administrative authority of any jurisdiction may grant a waiver from compliance with any standard adopted hereunder for a particular building or structure if it determines that compliance with the particular standard is impractical: PROVIDED, That such a determination shall be made no later than at the time of issuance of the building permit for the construction, remodeling, or rehabilitation: PROVIDED FURTHER, That the board of appeals provided for in chapter 1 of the Uniform Building Code shall have jurisdiction to hear and decide appeals from any decision by the administrative authority regarding a waiver or failure to grant a waiver from compliance with the standards adopted pursuant to RCW 70.92.100 through 70.92.160. The provisions of the Uniform Building Code regarding the appeals process shall govern the appeals herein.
RCW 70.92.160