Multnomah County, OR Building Setbacks & Zoning: Lot Coverage Limits (2026)
Key Facts
- Max lot coverage
- 40 percent
- Applies to zone
- MR-4 (Urban Medium Density Residential)
- Min lot size (single-family)
- 4,500 sq ft
- Max structure height
- 35 feet
Summary
In unincorporated Multnomah County's MR-4 residential zone, buildings can cover no more than 40 percent of the lot, on top of a 4,500-square-foot minimum lot size.
(I) The maximum lot coverage shall be 40 percent.
(J) Minimum Yard Dimensions – Feet Front Side Street Side Rear Interior 20 5 N/A 15 Lot Corner 20 5 10 15 Lot
Maximum Structure Height - 35 feet.
(1) The minimum yard and other setbacks for a mobile home park shall be as required under MCC 39.9610.
(2) In the event a front yard less than the minimum has been legally established on one or both of the adjacent lots, the minimum front yard for a single family detached or two-unit dwelling on an interior lot may be reduced to the average of the established or required adjoining front yards.
(3) The rear yard of a corner lot may be reduced to five feet, provided that the front yard is not less than 20 feet, the street side yard is not less than 10 feet and the interior side yard is not less than 15 feet.
(K) In the case of an apartment structure in this base zone, a yard equal to the structure height shall be provided between the structure in this base zone and any adjacent LR base zone lot line. In acting on a final design review plan under MCC 39.8030, the Planning Director may modify or waive this requirement upon a finding that the factors listed in MCC 39.8050(C)(1) are satisfied.
(S-1 2023)
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Full Breakdown
Multnomah County Code § 39.4990(I) caps lot coverage at 40 percent for property zoned Urban Medium Density Residential (MR-4) in unincorporated county land. That subsection sits alongside the zone's other dimensional standards: a 4,500-square-foot minimum lot for a single-family detached dwelling, a 20-foot front yard, 5-foot interior side yards, and a 35-foot maximum structure height. This governs only unincorporated county territory outside Portland, Gresham, Troutdale, Fairview and Wood Village, which apply their own zoning codes. Other base zones in Chapter 39 carry their own coverage figures, so confirm the parcel's zoning designation before relying on the 40 percent number.
Violations & Fines
Building beyond the 40 percent coverage cap without an approved variance is a zoning code violation; the County Land Use Planning Division can require removal or modification of the noncompliant structure and withhold occupancy approval until the site conforms.
Frequently Asked Questions
Does this 40 percent cap apply inside Portland?
What counts toward the 40 percent lot coverage?
Sources & Official References
Other rules in Multnomah County
Compare Multnomah County to another location·View the Oregon building setbacks & zoning overview
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