RCW 11.96A.170: Trial by jury.

If a party is entitled to a trial by jury and a jury is demanded, and the issues are not sufficiently made up by the written pleadings on file, the court, on due notice, shall settle and frame the issues to be tried. If a jury is not demanded, the court shall try the issues, and sign and file its findings and decision in writing, as provided for in civil actions.