ADU rules in Clark County, WA — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
In the urban growth area you may build up to two accessory dwelling units per legal lot, each capped at 1,000 sq ft (up to 1,500 sq ft on lots of 20,000+ sq ft). Rural zones (RADU) allow one, capped at 1,500 sq ft. No parking is required for urban
Clark County Code 40.260.020 governs urban ADUs: up to two per lot accessory to a single-family dwelling, via internal conversion, addition, garage conversion, or one/two detached structures. Each must meet the zone's lot coverage, setback, and height standards, connect to public sewer and water, and be at least 150 sq ft. Rural ADUs (RADU) under CCC 40.260.022 are limited to one per lot, must comply with fire/health/safety codes, provide one on-site parking space, and cap at 1,500 sq ft. Both receive a 75% reduction in school and transportation impact fees. City ADU rules differ inside Vancouver, Camas, etc.
Building an ADU without permits or exceeding size/setback standards is a code violation subject to stop-work orders, permit denial, and Title 32 nuisance/civil enforcement by Clark County Community Development.
Other ordinances people look up for this city. Green dot = verified primary-source excerpt.
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See how Clark County's adu rules rules stack up against other locations.
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