Wash. Admin. Code § 296-150C-1510
In addition to the requirements of the International Mechanical Code and the Washington State Energy Code air ducts for:
[Statutory Authority: Chapter 43.22 RCW and 2003 c 291. WSR 05-01-102, § 296-150C-1510, filed 12/14/04, effective 2/1/05. Statutory Authority: RCW 43.22.340, [43.22.]355, [43.22.]360, [43.22.]432, [43.22.]440 and [43.22.]480. WSR 96-21-146, § 296-150C-1510, filed 10/23/96, effective 11/25/96.]