Garage conversion rules in Pierce County, WA — sometimes called garage-to-ADU or accessory living unit conversions — govern permits, ceiling height, egress, and parking replacement.
Converting a garage into living space in unincorporated Pierce County requires a building permit, and creating an independent unit is treated as an accessory dwelling unit under PCC 18A.37.120 with size limits.
Pierce County requires a building permit for garages, and any conversion that creates habitable space must meet current residential building and zoning standards. When a garage is converted into an independent living unit, the county treats it as an accessory dwelling unit and the owner applies for an ADU building permit under PCC 18A.37.120. ADU square footage is calculated on interior habitable area but excludes the garage, and the unit may not exceed 1,000 square feet inside the Urban Growth Area or 1,250 square feet outside it. Conversion of an existing detached structure to an ADU is allowed within side or rear setbacks inside the UGA. Habitable-space conversions are never permit-exempt.
Converting a garage to living or sleeping space without a permit, or without meeting egress, energy, and ADU standards, can lead to code enforcement, required permitting, or removal of the illegal conversion.
Other ordinances people look up for this city. Green dot = verified primary-source excerpt.
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See how Pierce County's garage conversions rules stack up against other locations.
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