Oregon Tiny Home Zoning Laws
Oregon has a genuine claim other states in this series don't: it was the first state in the country to eliminate single-family-only zoning statewide, and it hasn't slowed down since.
- First state nationally to eliminate single-family-only zoning statewide (HB 2001, 2019).
- Cities with 10,000+ residents must allow middle housing (duplexes, triplexes, cottage clusters) by-right in every residential zone.
- HB 2138 (2025) goes further than any other state we've researched: it retroactively invalidates HOA covenants blocking ADUs, even ones written before the law existed.
- A restrictive HOA agreement predating this law can no longer block a legally compliant ADU.
- No court enforcement precedent yet exists for HB 2138 as of this writing — the law is new.
A real historic first, plus a powerful 2025 follow-up: Oregon's House Bill 2001, signed August 8, 2019, made it the first state to require all cities with 10,000+ residents to allow middle housing (duplexes, triplexes, cottage clusters) by-right in every residential zone.7 More recently, House Bill 2138, part of a five-bill housing package signed in July 2025, goes further than any other state law we found in this series: it retroactively invalidates private CC&R and HOA covenants that restrict ADUs or middle housing, amending ORS 93.277 and 94.776 so this applies even to governing documents adopted years before the bill itself.3,8 That means even a restrictive HOA agreement predating this law can no longer block a legally compliant ADU in Oregon.
1. The Statewide ADU Mandate
Oregon requires ADUs to be permitted in cities with more than 2,500 residents and counties with more than 15,000 residents.5 Foundation-built tiny homes under 400 square feet are reviewed under the Oregon Residential Specialty Code with Appendix Q.6
2. Portland: One of the Most ADU-Friendly Cities Anywhere
| Detail | Portland Rule |
|---|---|
| Maximum size | 800 sq ft or 75% of the primary home's floor area, whichever is less1,3 |
| Setbacks | Approximately 5 ft rear setback for detached ADUs3 |
| Owner-occupancy | Not required — removed in 2020, so you can build and rent an ADU as a non-owner-occupant1 |
| Parking | Not required for most ADUs3 |
| Permit cost & timeline | Roughly $1,900 permit and review fee plus System Development Charges around $19,000; 30–45 day review3 |
| Typical build cost | $150,000–$300,000; garage conversions $70,000–$160,000; prefab $100,000–$240,0003 |
3. Homes on Wheels Have a Narrower, More Specific Path
Portland allows one occupied recreational vehicle or THOW per residential lot that already has a primary dwelling, provided it stays mobile, meets utility hookup requirements, sits on a paved surface, and follows setback rules.4 Senate Bill 1013 (2023) expanded THOW options further in counties that opt in, allowing extended stays where proper utility connections exist.2 This is more flexible than most states in this series, but it's still opt-in by county, not automatic statewide.
4. Real County Examples Beyond Portland
| County | Notable Detail |
|---|---|
| Deschutes County | Allows tiny homes with an approved permit and has adopted rural ADU provisions under Senate Bill 3914 |
| Clackamas County | Amended its Zoning and Development Ordinance to allow ADUs in rural residential areas4 |
| Benton County | Adopted the Oregon Residential Specialty Code with clearly outlined tiny home procedures; homes up to 400 sq ft permitted on private land with a permanent foundation4 |
| Eugene & Bend | Both have adopted ADU-friendly policies, with system development charges waived for small ADUs in some cases6 |
5. A Real Budget Example
One frequently cited example: a Eugene couple bought a 0.15-acre R-1 lot for $85,000, built a 380 sq ft ADU tiny home for $110,000, paid $6,500 in permits and fees, and spent $18,000 on site work including a concrete slab foundation and utility hookups to existing city water and sewer.4 This kind of real total-cost breakdown is more useful than a single "cost per square foot" number, since permits and site work were nearly 20% of the total project cost in this example.
6. Wildfire and Climate Considerations
Zoning overlay districts, flood zones, and wildfire risk zones can all add extra requirements, particularly in southern and eastern Oregon, where Oregon Department of Forestry defensible-space rules may affect placement and construction.4 A zoning verification letter from the county planning office, typically $50–$200, is a small cost that can prevent an expensive mistake on a specific parcel.4
Research record: Because HB 2138's retroactive invalidation of HOA and CC&R covenants is an unusually strong claim, we checked it directly against the enrolled bill text and its ORS amendments rather than relying on secondary summaries alone. We have not found a case where this provision has actually been tested against a specific HOA in court as of this writing; the statute is new enough that enforcement precedent may still be developing. Information last checked August 2026.
How to Verify Your Specific Situation
- Confirm your target city meets the population threshold that triggers Oregon's statewide ADU mandate, and check current local implementation.
- If your property has HOA or CC&R restrictions, note that HB 2138 may void restrictions specifically targeting ADUs or middle housing as of July 2025.
- For homes on wheels, confirm whether your target county has opted into SB 1013's extended-stay provisions.
- In southern or eastern Oregon, budget time and cost for wildfire defensible-space compliance before finalizing plans.
See what it costs to power and plumb your build.
Read the Off-Grid Utility Planning GuideSources
- Steadily, "ADU Housing Laws and Regulations in Portland - 2026"; primary source: Enrolled House Bill 2001 (2019), official text via the Oregon Legislative Information System.
- Great Lakes Tiny Home, "What Counties in Oregon Allow Tiny Houses."
- ADU Zoning Hub, "Portland ADU Rules (2026): Size Limits, Permit Cost & No-Parking Rules."
- FindATinyHouse, "Tiny Home Zoning Laws in Oregon: Complete 2026 Guide."
- Zook Cabins, "Tiny Home Regulations In Oregon: The Complete Guide."
- Little Houses For Sale, "Tiny House Zoning in Oregon."
- PropertyZoned, "Oregon ADU Rules: State Law, Portland Rules, Costs & Process 2026."
- Oregon Legislative Information System (olis.oregonlegislature.gov), Enrolled House Bill 2138 (2025), amending ORS 93.277 and 94.776.
