Wash. Rev. Code § 64.60.005
The legislature finds and declares that the public policy of this state favors the marketability of real property and the transferability of interests in real property free of title defects or unreasonable restraints on alienation. The legislature further finds and declares that private transfer fee obligations violate this public policy by impairing the marketability and transferability of real property and by constituting an unreasonable restraint on alienation regardless of the duration of the obligation to pay a private transfer fee, the amount of a private transfer fee, or the method by which any private transfer fee is created or imposed. Thus, the legislature finds and declares that a private transfer fee obligation may not run with the title to real property, touch or concern the real property, or otherwise bind subsequent owners of real property under any common law or equitable principle.
RCW 64.60.005