Can you build a duplex in Portland, OR?
Portland has dedicated multi-dwelling zones and broader residential zoning categories, but the supplied research does not include the current use table entries or dimensional standards needed to determine whether a specific small multifamily proposal is by right on a given site.
Confidence: low · Last researched May 2026
Dimensional standards in Portland, OR
| R20 — Minimum lot area for one ADU on a lot with a primary structure | 10,000 sq. ft. |
| R10 — Minimum lot area for one ADU on a lot with a primary structure | 5,000 sq. ft. |
| R7 — Minimum lot area for one ADU on a lot with a primary structure | 3,500 sq. ft. |
| R5 — Minimum lot area for one ADU on a lot with a primary structure | 2,500 sq. ft. |
| R2.5 — Minimum lot area for one ADU on a lot with a primary structure | 1,500 sq. ft. |
| R20 — Minimum lot area for one ADU with an attached house | 12,000 sq. ft. |
| R10 — Minimum lot area for one ADU with an attached house | 6,000 sq. ft. |
| R7 — Minimum lot area for one ADU with an attached house | 4,200 sq. ft. |
| R5 — Minimum lot area for one ADU with an attached house | 3,000 sq. ft. |
| R2.5 — Minimum lot area for one ADU with an attached house | 1,500 sq. ft. |
Related questions
Are ADUs allowed in Portland, OR?
An accessory dwelling unit is a smaller home on the same lot as the main one and must contain independent living facilities for living, cooking, eating, sleeping, and sanitation. ADUs may be created by internal conversion, addition, conversion of an accessory structure, or new detached construction.
What is the minimum lot size in Portland, OR?
Minimum lot size depends on the zoning district — R20: 10,000 sq. ft.; R10: 5,000 sq. ft.; R7: 3,500 sq. ft.; R5: 2,500 sq. ft..
What zoning districts are in Portland, OR?
Portland, OR includes districts such as Single-Dwelling Residential Zones (RF, R20, R10, R7, R5, R2.5), Multi-Dwelling Zones (RM1, RM2, RM3, RM4, RX, RMP), Commercial / Mixed Use Zones (CR, CM1, CM2, CM3, CE, CX), Employment and Industrial Zones (EG1, EG2, EX, IG1, IG2, IH), Campus Institutional Zones (IR, CI1, CI2).
Full investor analysis
The full Portland, OR report breaks down duplex and 2–4 unit feasibility by district, the approval path, and the density/dimensional limits that decide whether the numbers work. First town report is free.
Get the full Portland, OR report free →More about Portland, OR zoning
- Can you build an ADU in Portland, OR?→
- Are short-term rentals allowed in Portland, OR?→
- Is mixed-use development allowed in Portland, OR?→
This summary is AI-generated from public municipal sources and is not legal, engineering, or land-use advice. Always verify zoning with Portland, OR officials before making decisions.
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