Multnomah County, OR Building Safety: Fire Sprinkler Requirements (2026)
Key Facts
- Standard secondary zone
- 100 feet minimum
- Sprinkler trigger
- reduced zone under 50 feet
- System required
- central-station monitored 13D sprinklers
- 50-100 ft alternative
- central-station monitored alarm system
- Fence buffer
- no combustible fence within 12 feet
- Governing section
- MCC § 39.4155(B)
Summary
In unincorporated Multnomah County's farm and forest zones, the standard secondary fire safety zone around a dwelling is 100 feet. A landowner can shrink that buffer under MCC 39.4155, but if the reduced zone drops below 50 feet the dwelling must carry a central-station monitored 13D fire sprinkler system.
(B) Exceptions to secondary fire safety zones shall only be granted upon satisfaction of the following standards: ... (2) If the proposed secondary fire safety zone is less than fifty feet, the dwelling or structure shall be constructed in accordance with the International Fire Code Institute Urban-Wildland Interface Code Section 504 Class 1 Ignition Resistant Construction as adopted August, 1996, or as later amended, and ... (5) A dwelling shall have a central station monitored 13D sprinkler system if the secondary fire safety zone equivalents of subsection (B) (2) above are utilized. Expansions of existing single family dwellings as allowed by MCC 39.4075 (A) shall not be required to meet this standard, but shall satisfy the standard of MCC 39.4115(C)(3) and (E).
Full Breakdown
4115(A) requires every new dwelling in the county's Exclusive Farm Use and Commercial Forest Use base zones to maintain a primary fire safety zone of at least 30 feet and a secondary fire safety zone of at least 100 feet around the structure. 4155(A). Approval turns on the construction and equipment standards in subsection (B): if the reduced zone still falls between 50 and 100 feet, the dwelling must meet International Fire Code Institute Urban-Wildland Interface Code Section 505 Class 2 Ignition Resistant Construction, and combustible fences are barred within 12 feet of the structure.
Push the reduced zone below 50 feet, and the stricter Section 504 Class 1 construction applies, plus a mandatory central-station monitored NFPA 13D residential fire sprinkler system under subsection (B)(5). A reduced zone of 50 to 100 feet instead triggers a central-station monitored fire alarm system under (B)(4), a lighter alternative to sprinklers. 4115(C)(3) and (E). Multnomah County's Land Use Planning Division reviews each exception as part of the dwelling's zoning approval, and the local Rural Fire Protection District is the resource named in the code for verifying defensible-space compliance.
Violations & Fines
Occupying a dwelling that accepted a reduced secondary fire safety zone without installing the required 13D sprinkler or alarm system voids the MCC 39.4155 exception; Multnomah County Land Use Planning can require a retrofit or revoke the approval, and occupancy sign-off can be withheld until the monitored system is installed and active. Combustible fencing placed within the 12-foot buffer around the dwelling is a separate standards violation subject to correction under the same exception review.
Frequently Asked Questions
Does every home in unincorporated Multnomah County need fire sprinklers?
What is a secondary fire safety zone?
What happens if I expand my existing house instead of building new?
Who reviews a reduced fire safety zone exception?
Sources & Official References
Other rules in Multnomah County
Compare Multnomah County to another location·View the Oregon building safety overview
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