ADU rules in Clackamas County, OR — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
In unincorporated Clackamas County, ZDO Section 839 allows one ADU per single-family dwelling. Inside an urban growth boundary the ADU maxes at 900 sq ft (500 sq ft in R-2.5). Oregon HB 2001 mandates ADUs statewide. Cities set their own rules.
Clackamas County's Zoning & Development Ordinance Section 839 governs ADUs in the unincorporated county. Inside an urban growth boundary or unincorporated community, only one ADU is allowed per detached single-family or manufactured dwelling, capped at 900 sq ft (500 sq ft in the R-2.5 district), and none in a cottage-cluster or manufactured-dwelling park. Outside a UGB (rural), an ADU needs a lot of record of at least two acres with one dwelling, a 900 sq ft cap, and must sit within 100 feet of the primary home; rural ADUs cannot be used as short-term rentals. Effective Sept. 3, 2024, ADUs were expanded to more rural-residential areas. Oregon's 2019 HB 2001 requires cities to permit ADUs.
Building or occupying an ADU without land-use and building permits is a zoning violation enforced by county Code Enforcement; unpermitted work can be ordered removed and fees assessed.
Other ordinances people look up for this city. Green dot = verified primary-source excerpt.
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Backyard composting of yard debris and food scraps is allowed and encouraged in Clackamas County; no permit is needed for a home compost pile. Commercial-sca...
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See how Clackamas County's adu rules rules stack up against other locations.
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