Wash. Rev. Code § 35.50.260
In foreclosing local improvement assessments the action shall be tried to the court without a jury. If the parties interested in any particular lot, tract, or parcel default, the court may enter judgment of foreclosure and sale as to such parties and lots, tracts, or parcels and the action may proceed as to the remaining defendants and lots, tracts, or parcels. Judgment and order of sale may be entered as to any one or more separate lots, tracts, or parcels involved in the action and the court shall retain jurisdiction to others.
The judgment shall specify separately the amount of the installments with interest, penalty, and all reasonable administrative costs, including, but not limited to, the title searches, chargeable to each lot, tract, or parcel. The judgment shall have the effect of a separate judgment as to each lot, tract, or parcel described in the judgment, and any appeal shall not invalidate or delay the judgment except as to the property concerning which the appeal is taken. In the judgment the court shall order the lots, tracts, or parcels therein described sold by the city or town treasurer or by the county sheriff and an order of sale shall issue pursuant thereto for the enforcement of the judgment.
In all other respects, the trial, judgment, and appeals to the supreme court or the court of appeals shall be governed by the statutes governing the foreclosure of mortgages on real property.
Prior to the sale of the property, if the property is shown on the property tax rolls under unknown owner or if the property contains a residential structure having an assessed value of two thousand dollars or more, the treasurer shall order or conduct a title search of the property to determine the record titleholders and all persons claiming a mortgage, deed of trust, or mechanic's, laborer's, material supplier's, or vendor's lien on the property.
At least thirty days prior to the sale of the property, a copy of the notice of sale shall be mailed by certified and regular mail to all defendants in the foreclosure action as to that parcel, lot, or tract and, if the owner is unknown or the property contains a residential structure having an assessed value of two thousand dollars or more, a copy of the notice of sale shall be mailed by regular and certified mail to any additional record titleholders and persons claiming a mortgage, deed of trust, or mechanic's, laborer's, material supplier's, or vendor's lien on the property.
In all other respects, the procedure for sale shall be conducted in the same manner as property tax sales described in RCW 84.64.080.
RCW 35.50.260
Severability-1982 c 91: See note following RCW 35.50.030.
Foreclosure of real estate mortgages and personal property liens: Chapter 61.12 RCW.
Foreclosure of special assessments by water-sewer districts-Attorneys' fees: RCW 57.16.150.