The principles of law and equity, including the law of corporations and unincorporated associations, the law of real property, and the law relative to capacity to contract, principal and agent, condemnation, estoppel, fraud, misrepresentation, duress, coercion, mistake, receivership, substantial performance, or other validating or invalidating cause supplement the provisions of this chapter, except to the extent inconsistent with this chapter.
RCW 64.34.070