Wash. Rev. Code § 7.28.180
If the judgment be in favor of the plaintiff for the recovery of the realty, and of the defendant upon the counterclaim, the plaintiff shall be entitled to recover such damages as he or she may be found to have suffered through the withholding of the premises and waste committed thereupon by the defendant or those under whom he or she claims, but against this recovery shall be offset pro tanto the value of the permanent improvements and the amount of said taxes and assessments with interest found as above provided. Should the value of improvements or taxes or assessments with interest exceed the recovery for damages, the plaintiff, shall, within two months, pay to the defendant the difference between the two sums and upon proof, after notice, to the defendant, that this has been done, the court shall make an order declaring that fact, and that title to the improvements is vested in him or her. Should the plaintiff fail to make such payment, the defendant may at any time within two months after the time limited for such payment to be made, pay to the plaintiff the value of the land apart from the improvements, and the amount of the damages awarded against him or her, and he or she thereupon shall be vested with title to the land, and, after notice to the plaintiff, the court shall make an order reciting the fact and adjudging title to be in him or her. Should neither party make the payment above provided, within the specified time, they shall be deemed to be tenants in common of the premises, including the improvements, each holding an interest proportionate to the value of his or her property determined in the manner specified in RCW 7.28.170: PROVIDED, That the interest of the owner of the improvements shall be the difference between the value of the improvements and the amount of damages recovered against him or her by the plaintiff.
RCW 7.28.180