Lewis County, WA Accessory Structures: Garage Conversions (2026)

LCC § 17.17.130 governs accessory dwelling units within the Packwood and Onalaska Small Town Urban Growth Areas of unincorporated Lewis County. Subsection (1) caps the total at no more than two ADUs per lot in conjunction with a single-family structure. Subsection (2) is the garage conversion rule: a garage may be converted to an ADU even if the conversion violates existing setback or lot coverage requirements, provided the converted unit meets all other applicable laws, including building code, sewage and water requirements. That carve-out only reaches setbacks and lot coverage; it does not excuse the ADU from parking, design or utility standards found elsewhere in Chapter 17.17.

Subsection (3) separately allows a detached ADU to be sited directly on a lot line where that line abuts a public alley, unless the county routinely plows snow on the alley, in which case the ADU must be set back enough to keep the alley clear. Lewis County Community Development reviews ADU permits, including garage conversions, as part of the building permit process; because the ADU still has to satisfy the building code (Chapter 15.05 LCC) and on-site sewage rules (Chapter 8.40 LCC) where applicable, a conversion cannot skip septic capacity or structural review even though it is exempt from the zone's setback and coverage math. The section was adopted by Ord. 1367 (Exh. C) in 2025.