Oregon Revised Statutes Property Rights and Transactions § 90.145

(1) A tenant who occupies or an applicant who will occupy a dwelling unit and who conducts repairs, routine maintenance or cleaning services on that dwelling unit in exchange for a reduction in rent pursuant to a written or oral agreement with the landlord is not an employee of the landlord.

(2) A tenant or an applicant described in subsection (1) of this section may not conduct electrical or plumbing installation, maintenance or repair unless properly licensed under ORS 479.510 to 479.945 or ORS chapter 693.  The tenant or applicant is not required to obtain a plumbing contractor license under ORS 447.040 to perform work under this section.

(3) Nothing in this section diminishes the obligations of a landlord to maintain the dwelling unit in a habitable condition under ORS 90.320 or 90.730.

(4) Any electrical or plumbing installation, maintenance or repair work performed by a tenant or an applicant under this section must comply with ORS 447.010 to 447.156 and 479.510 to 479.945.