Lane County, OR Accessory Structures: ADU Rules (2026)
ADU rules in Lane County, OR, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Minimum lot size
- 2 acres
- Max ADU floor area
- 900 sq ft usable floor area
- Max distance from house
- 100 feet
- Permit type
- Type I, Lane Code Chapter 14
- Vacation rental
- Barred by recorded covenant
- Historic-home conversion cap
- 120% of original floor area
- Late-compliance penalty
- Up to $2,000/violation/day
Summary
Lane County allows one accessory dwelling unit per lot in the Rural Residential zone under Lane Code section 16.290(8), but only on parcels of at least two acres that already hold a single-family home. The ADU is capped at 900 square feet of usable floor area, must sit within 100 feet of the existing house, and needs a Type I land-use permit plus written fire-district certification before the county will approve it.
(a) Purpose. The provisions of this section are intended to implement state law authorizing the development of accessory dwelling units (ADUs) to provide additional housing opportunities on rural lands and to encourage the preservation of historic housing stock. ... (c) Criteria for ADUs. A lot or parcel may qualify for one (1) ADU pursuant to the criteria under either subsection (xi) or (xii) below and provided: (i) The lot or parcel is at least two acres in size; (ii) At least one single-family dwelling is sited on the lot or parcel; ... (viii) ADUs may be allowed subject to submittal of a Type I application pursuant to the procedures of LC Chapter 14. ... (xi) An ADU in the rural residential zone is allowed subject to LC 16.290(8)(c)(i) through (x) and must meet all of the following standards: (aa) The ADU will be located no farther than 100 feet from the existing single-family dwelling, measured from a wall of the single-family dwelling to the nearest part of the usable floor area of the ADU. (bb) The ADU will not include more than 900 square feet of usable floor area as defined by LC 16.290(8)(b)(vi).
Full Breakdown
137, and cannot later be divided so the house and the ADU end up on separate parcels. Only one ADU is allowed per lot, reviewed through a Type I application under Lane Code Chapter 14, which the Planning Director decides administratively without a public hearing. 410, plus a written fire-district certification and a recorded evacuation plan naming a staged evacuation area. Owners must also record a covenant with Lane County Deeds and Records promising the ADU will never be used for vacation occupancy, defined as short-term rental of 45 days or less to someone whose principal residence is elsewhere.
392. A second path, subsection (c)(xii), lets an owner build a new single-family home and convert an existing "historic home" built between 1850 and 1945 into the ADU, capped at 120 percent of that historic home's original floor area.
Violations & Fines
Lane Code Chapter 16 zoning standards, including this ADU section, are enforced under Lane Code 5.025.025. An Enforcement Officer who finds a violation on real property, such as an ADU built past the 100-foot line, over 900 square feet, or without the required Type I approval, issues an Order to Comply listing the violated sections and a compliance deadline. Penalties accrue at up to $2,000 per violation per day if the deadline passes, rising to $2,500 per day for commercial gain, and unpaid amounts become a lien against the property.
Frequently Asked Questions
How big can an ADU be in unincorporated Lane County?
Do I need a permit to build a rural ADU?
Can I rent my Lane County ADU as a vacation rental?
What happens if my ADU doesn't meet the fire safety rules?
Sources & Official References
Other rules in Lane County
How Lane County compares: Easiest Cities to Build an ADU·Compare Lane County to another location·View the Oregon accessory structures overview
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