Oregon · OR
ADU laws & builders in Oregon
Oregon's HB 2001 made ADUs legal statewide on single-family lots. Portland has its own ADU permitting process with streamlined options for detached ADUs. Smaller cities are catching up with their own pre-approved plan offerings.
Last reviewed: 2026-05-29
Are ADUs legal in Oregon?
Yes. Oregon's HB 2001 required cities of a certain size to allow ADUs and other 'middle housing' on land zoned for single-family homes. In practice, most Oregon homeowners in and around metro areas can add an ADU. Portland goes further than the state minimum, with established detached-ADU rules and a track record of approved projects.
Key rules that affect your build
Oregon limits owner-occupancy requirements and parking mandates for many ADUs, and Portland has waived or reduced system development charges (SDCs) for ADUs at various points — a meaningful cost saver. Size limits, height, and setbacks are set locally, so the exact envelope you can build depends on your city and lot.
Cost and timeline in Oregon
A permitted detached ADU in the Portland area generally runs $180K–$380K turnkey; garage conversions cost less. Expect roughly 8–13 months from contract to final inspection. A builder familiar with your city's process will navigate SDC waivers and design review far faster than a generalist.
Official source
We summarize Oregon's ADU rules in plain English. For the authoritative, always-current legal detail, go straight to the source:
Oregon DLCD — Housing ChoicesAlways verify current rules with the official source before making decisions.
Pre-approved ADU plan programs in Oregon
- Portland — Portland ADU Permitting
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