Accessory Structures in Hillsboro, OR (2026)
4 verified accessory structures rules for Hillsboro, Oregon, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Hillsboro allows ADUs on all single-family lots per Oregon HB 2001. ADUs are capped at 800 square feet. Both attached and detached types are permitted.
Hillsboro ADU / Accessory Dwelling Unit Rules
Some RestrictionsShed Rules
Small sheds under 200 square feet generally do not need permits in Hillsboro. Larger structures require permits and must meet setbacks.
Hillsboro Shed & Outbuilding Rules
Few RestrictionsHMC 12.40.104
Accessory Structures and Carports HMC 12.40.104 requires a minimum distance of separation between any structure and the property line. This is to prevent the rapid spread of fire from one lot to another. Contact the Planning Division to find what the minimum is where you live.
Garage Conversions
Garage conversions in Hillsboro require building permits. If creating an independent unit, it may qualify as an ADU under Oregon law.
Hillsboro Garage Conversion Rules
Some RestrictionsCarport Rules
Hillsboro treats a carport as an accessory structure under Community Development Code Section 12.40.104. In residential zones, side and rear setbacks may be reduced to three feet for an accessory structure meeting Subsection 12.40.104.B. Setbacks are measured to the support posts closest to the driveway, or to the roof edge.
Carport Rules in Hillsboro
Some RestrictionsLooking for Washington County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Hillsboro city rules.
Accessory Structures in Washington County →