Franklin County, WA Accessory Structures: ADU Rental Restrictions (2026)

Two separate subsections of the Franklin County zoning code restrict rental use around accessory dwelling units. 050(N), governing attached accessory apartments, states that the renting of rooms for lodging purposes is prohibited in single-family homes where there is an accessory dwelling unit. 050 cannot also rent out individual bedrooms in the main house as separate lodging. 060, which governs detached accessory dwelling units on lots of two acres or more, goes further in Subsection L: an accessory dwelling unit may not be rented, nor may the rooms therein be rented, nor may the accessory dwelling unit be used for business purposes.

Detached ADUs under that section are already limited to housing aged parents, aged relatives, disabled children or disabled relatives under Subsection G, so the rental ban in Subsection L reinforces that a detached unit cannot become a standalone rental property or short-term rental once a conditional use permit is granted. 050(G) for attached apartments, and together they prevent a single-family lot with an ADU from functioning as a multi-unit rental property. 060.