Wash. Rev. Code § 59.20 § 59.20.210

(1)(a) If at any time during the tenancy, the landlord fails to carry out any of the duties imposed by RCW 59.20.130 , and notice of the defect is given to the landlord pursuant to RCW 59.20.200 , the tenant may submit to the landlord or the landlord's designated agent by certified mail or in person at least two bids to perform the repairs necessary to correct the defective condition from licensed or registered persons, or if no licensing or registration requirement applies to the type of work to be performed, from responsible persons capable of performing such repairs. Such bids may be submitted to the landlord at the same time as notice is given pursuant to RCW 59.20.200 .
(b) Upon receipt of any such bids, the landlord shall provide the tenant with a copy of the notice regarding the manufactured/mobile home dispute resolution program that the attorney general is required to produce pursuant to RCW 59.30.030 (3)(a) and that landlords are required to post pursuant to RCW 59.30.030 (3)(b)(i).
(2) If the landlord fails to commence repair of the defective condition within a reasonable time after receipt of notice from the tenant, the tenant may contract with the person submitting the lowest bid to make the repair, and upon the completion of the repair and an opportunity for inspection by the landlord or the landlord's designated agent, the tenant may deduct the cost of repair from the rent in an amount not to exceed the sum expressed in dollars representing one month's rental of the tenant's mobile home space in any calendar year. When, however, the landlord is required to begin remedying the defective condition within thirty days under RCW 59.20.200 , the tenant cannot contract for repairs for at least fifteen days following receipt of bids by the landlord. The total costs of repairs deducted by the tenant in any calendar year under this subsection shall not exceed the sum expressed in dollars representing one month's rental of the tenant's mobile home space.
(3) Two or more tenants shall not collectively initiate remedies under this section. Remedial action under this section shall not be initiated for conditions in the design or construction existing in a mobile home park before June 7, 1984.
(4) The provisions of this section shall not:
(a) Create a relationship of employer and employee between landlord and tenant; or
(b) Create liability under the worker's compensation act; or
(c) Constitute the tenant as an agent of the landlord for the purposes of mechanics' and material suppliers' liens under chapter 60.04 RCW.
(5) Any repair work performed under this section shall comply with the requirements imposed by any applicable code, statute, ordinance, or rule. A landlord whose property is damaged because of repairs performed in a negligent manner may recover the actual damages in an action against the tenant.
(6) Nothing in this section shall prevent the tenant from agreeing with the landlord to undertake the repairs in return for cash payment or a reasonable reduction in rent, the agreement to be between the parties, and this agreement does not alter the landlord's obligations under this chapter.