Do I need a permit for basement finishing in Unincorporated Multnomah County?
Yes. In Oregon, basement finishing generally requires a permit, and Unincorporated Multnomah County is no exception.
Creating new habitable space, a new toilet room, or a new bathroom requires a building permit (ORSC R105.1.1), and BCD lists finishing a basement to make additional living space as permitted work. Oregon kept its long-standing rule that basements and every sleeping room need an operable emergency escape and rescue opening; where a basement has sleeping rooms, each one needs its own (ORSC R310.1 as amended effective Oct. 1, 2024). Turning an unconditioned basement into conditioned space is a change of use under ORSC N1101.2.3, and the permitted work triggers smoke alarms (R314.2.2) and carbon monoxide alarms (R315.2.2) for the dwelling.
Local detail for Unincorporated Multnomah County: Multnomah County handles zoning only. Building permits for unincorporated areas are issued under agreement by the City of Gresham (most of unincorporated east Multnomah County), the City of Portland, or the City of Troutdale, depending on the address. The office listed is Gresham Permit Services; confirm which city serves your address.
Documents you may need
- Building permit applicationRequired
- Floor plan showing rooms, egress windows, stairs, and smoke and CO alarm locationsRequired
- Insulation details for walls and floors of the finished spaceLikely required
- Separate electrical, plumbing, and mechanical permitsLikely required
Possible inspections
- Framing inspection
- Electrical, plumbing, and mechanical rough-in inspections
- Insulation inspection
- Final inspection
Frequently asked questions
- Do I need a permit for basement finishing in Unincorporated Multnomah County?
- Yes. In Oregon, basement finishing generally requires a permit, and Unincorporated Multnomah County is no exception. The documents and inspections sections on this page list what the building department typically asks for.
- Who issues the permit in Unincorporated Multnomah County?
- The local building department for Unincorporated Multnomah County handles permitting. This page lists its contact details and online portal. Your mailing city is not always the permitting authority, so confirm the jurisdiction before you apply.
- How do I find out the exact requirements for my project?
- Run the free PermitRoadmap check for your specific project and answers. It returns the likely permits, documents, inspections, and next steps, each linked to its official source.
PermitRoadmap is an independent informational service and is not affiliated with any city, county, state agency, or permitting authority. Results are informational and do not replace confirming requirements with the local permitting authority.