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Multnomah County, OR Accessory Structures: ADU Rental Restrictions (2026)

Significant Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified August 2026

Key Facts

Rule
Short-term ADU rental prohibited
Short-term defined
Occupancy under 30 consecutive days
Owner must
Sign and record a covenant
Applies in
MUA-20 and similar rural zones
Not covered
Portland has its own code

Summary

Multnomah County bars short-term rental of accessory dwelling units in rural residential zones like MUA-20 outside Portland; owners must record a covenant limiting the ADU to long-term occupancy.

City-specific rules exist: Gresham has its own adu rental restrictions rules that differ from Multnomah County's county-level regulations. If you live in Gresham, check the city-specific page instead.

(8) Short-term rental of the ADU is prohibited. For purposes of this subsection, short-term rental is defined as fee-based occupancy for a period less than 30 consecutive calendar days. ... (9) The land owner shall sign and record with the county a covenant stating that the ADU cannot be used for short-term rental, as defined in this section.

Full Breakdown

Multnomah County's zoning code allows one accessory dwelling unit per single-family lot in rural residential base zones such as Multiple Use Agriculture (MUA-20), but bars using it as a short-term rental. Multnomah County Code § 39.4310(L)(8) defines short-term rental as fee-based occupancy under 30 consecutive days and prohibits it outright; month-to-month leases for long-term purposes are exempt. Subsection (9) requires the landowner to sign and record a covenant with the county committing the ADU to long-term use only, running until the property is annexed into a city. This is unincorporated-county law only. Portland, Gresham and the county's other cities regulate ADU rentals under their own codes.

Violations & Fines

Renting an ADU short-term without the recorded covenant violates Multnomah County Code § 39.4310(L); county code enforcement can pursue civil penalties and require the owner to record the covenant or stop the rental.

Frequently Asked Questions

Can I rent my Multnomah County ADU on Airbnb for a weekend?
No. Multnomah County Code § 39.4310(L)(8) bans renting an ADU for less than 30 consecutive days, and a recorded covenant on the property enforces the restriction.
Does this rule apply to an ADU in Portland?
No. This is Multnomah County's code for unincorporated areas only. Portland regulates ADU rentals under its own municipal code, not this county ordinance.
Can I rent my county ADU month-to-month?
Yes. Month-to-month rental agreements for long-term purposes are excluded from the short-term rental definition in § 39.4310(L)(8).

Sources & Official References

Other rules in Multnomah County

All Multnomah County rules

Compare Multnomah County to another location·View the Oregon accessory structures overview

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ADU Rental Restrictions in Cities Across Multnomah County