RCW 43.22.455: Factory built housing and commercial structures, regulating installation of—Approval by department.

No factory built housing or factory built commercial structure shall be installed on a building site in this state after the effective date of the regulations adopted pursuant to RCW 43.22.480 unless it is approved and bears the insignia of approval of the department.

(1) Any factory built housing or factory built commercial structure bearing an insignia of approval of the department shall be deemed to comply with any laws, ordinances or regulations enacted by any city or county or any local enforcement agency which govern the manufacture and construction of factory built housing or factory built commercial structures or on-site housing.

(2) No factory built housing or factory built commercial structure which has been approved by the department shall be in any way modified prior to, or during installation by a manufacturer or installer unless approval of such modification is first made by the department.

(3) Department approval under RCW 43.22.450 through 43.22.490 is not required for a prefabricated enclosure for energy storage systems or electrical equipment associated with the generation, control, transformation, transmission, or distribution of energy installations under the ownership and exclusive control of an electric utility by established right where the enclosure entry is limited to qualified service personnel for maintenance, repair, or occasional monitoring of energy storage system units or electrical equipment and not occupied for other purposes.