Multnomah County, OR Fire Regulations: Wildfire Zones (2026)
Key Facts
- Primary fire safety zone
- 30 ft around structure
- Secondary fire safety zone
- 100 ft beyond primary
- Slope limit for building site
- under 40% grade
- Applies in
- Commercial Forest Use (CFU) zones
- Enforcing office
- County Planning Director
Summary
New dwellings in Multnomah County's Commercial Forest Use zones must maintain 30-foot primary and 100-foot secondary defensible-space fire breaks around every structure.
A secondary fire safety zone is a fire break extending a minimum of 100 feet in all directions around the primary safety zone. The goal of this safety zone is to reduce fuels so that the overall intensity of any wildfire is lessened. Vegetation should be pruned and spaced so that fire will not spread between crowns of trees. Small trees and brush growing underneath larger trees should be removed to prevent the spread of fire up into the crowns of the larger trees. Assistance with planning forestry practices which meet these objectives may be obtained from the State of Oregon Department of Forestry or the local Rural Fire Protection District. The secondary fire safety zone required for any dwelling or structure may be reduced under the provisions of MCC 39.4155.
(3) No requirement in (1) or (2) above may restrict or contradict a forest management plan approved by the State of Oregon Department of Forestry pursuant to the State Forest Practice Rules; and
(4) Required Primary and Secondary Fire Safety Zones shall be established within the subject tract as required by Table 1 above.
(5) Required Primary and Secondary Fire Safety Zones shall be maintained by the property owner in compliance with the above criteria listed under (1) and (2).
Full Breakdown
Unincorporated Multnomah County's forest-zoned land (Commercial Forest Use districts) requires a primary fire safety zone -- a 30-foot fire break around every dwelling or structure with trees spaced over 15 feet apart, crowns pruned above 8 feet, and other vegetation kept under 2 feet -- plus a secondary fire safety zone extending another 100 feet outward to cut overall wildfire intensity. On slopes of 10 percent or more, the primary zone must extend farther downhill (up to 100 additional feet on 25-40 percent slopes), and building sites over 40 percent slope aren't allowed. Portland and Gresham are not covered; each has its own code.
Violations & Fines
The Planning Director enforces compliance as a condition of the dwelling's land-use approval; failure to establish or maintain the required fire safety zones is a code violation subject to the county's standard land-use enforcement and fines under MCC Chapter 39.
Frequently Asked Questions
Does this apply to my Portland property?
Can the 100-foot secondary zone be reduced?
Sources & Official References
Other rules in Multnomah County
Compare Multnomah County to another location·View the Oregon fire regulations overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.