ADU Regulations in Hillsboro, Oregon
Updated September 29, 2026
Washington County's largest city and home to Silicon Forest tech companies, Hillsboro permits ADUs by right under Oregon's HB 2001. The growing demand for workforce housing near major employers like Intel drives interest in ADU construction.
Below is a summary of the key zoning rules applicable to Accessory Dwelling Units in Hillsboro as of 2026. Regulations are governed by Oregon's HB 2001 (2019) which requires ADU approval by-right in all residential zones statewide.
| Regulation | Requirement |
|---|---|
| Maximum Size | 1,200 sq ft |
| Property Setbacks | 5 ft rear, 5 ft side |
| Extra Parking Required | Not required |
| Owner Occupancy | Not required |
Additional Local Requirements for Hillsboro
- ADU by right in all residential zones (HB 2001)
- Minimum 200 sq ft
- Design review for historic districts only
- No owner occupancy requirement
📥 Download the Complete Hillsboro ADU Cheat Sheet
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Download the Complete Hillsboro ADU Cheat Sheet — $12Frequently Asked Questions About ADUs in Hillsboro
Can I build an ADU in Hillsboro?
Hillsboro follows Oregon's HB 2001. ADUs are permitted by right with no additional local restrictions for most properties.
What is the maximum ADU size allowed in Hillsboro?
ADUs in Hillsboro can be up to 1,200 square feet, subject to the property's zoning and lot coverage limits. Always confirm the exact allowed size with the Hillsboro planning department before designing your project.
What are the setback requirements for an ADU in Hillsboro?
ADUs in Hillsboro generally require setbacks of 5 ft rear, 5 ft side. Oregon's HB 2001 (2019) requires cities to allow ADUs in residential zones, but the exact setback figures come from Hillsboro's own code — confirm them with the city before you design.
Disclaimer: This guide summarises publicly available city zoning rules and is for general information only — it is not legal or architectural advice. Codes change; always confirm current requirements with the Hillsboro planning department before you design or build.