ADU Rules in Medford, Oregon

Medford, the seat of Jackson County and southern Oregon's largest city, sits in the Rogue River Valley along Bear Creek near the California border. The region is known for its proximity to Crater Lake, the Rogue River, and the Ashland Oregon Shakespeare Festival. The September 2020 Labor Day wildfires were a watershed moment for the region — the fires destroyed thousands of structures in the nearby communities of Talent and Phoenix, fundamentally reshaping awareness of wildfire risk in Jackson County. ADU construction in Medford is governed by the Medford Zoning Ordinance and Oregon statewide housing reform laws, with wildfire considerations playing a significant role for many properties.

Oregon Statewide ADU Law — Critical Context

Two Oregon laws govern ADU development in Medford and throughout the state:

Oregon HB 2001 (2019) requires cities with populations over 10,000 to allow middle housing — duplexes, triplexes, fourplexes, and cottage clusters — in all residential zones. Medford, with over 80,000 residents, must comply, ending single-family-only zoning citywide.

Oregon's statewide ADU framework is SB 1051 (2017) plus HB 2001 (2019) middle housing. HB 2098 (2021) is a rental-assistance bill, not ADU.

What Medford Allows

Under the Medford Zoning Ordinance and state law, the following ADU types are permitted in residential zones:

• Detached ADU: A freestanding structure on the same lot as the primary home, with its own kitchen, bathroom, and entrance.
• Attached ADU: An addition to the primary residence with a dedicated separate entrance and self-contained living facilities.
• Interior Conversion: Converting existing basement, attic, or interior rooms within the primary structure into a separate dwelling unit.
• Garage Conversion: Converting an existing attached or detached garage into habitable ADU space meeting Oregon building code habitability standards.

One ADU per single-family residential lot is permitted by right under state law.

Size and Setback Standards

Oregon law prohibits Medford from requiring ADUs smaller than 900 square feet or 75% of the primary dwelling's floor area, whichever is less. Typical setback standards for detached ADUs in Medford low-density residential zones include:

• Rear setback: 5 feet minimum
• Side setback: 5 feet minimum
• Height: Generally 15–18 feet maximum for detached ADUs

Legal nonconforming structures being converted to ADUs may maintain existing setbacks even if they don't conform to current new-construction standards.

Wildfire Risk — WUI Construction Requirements

Wildfire is a critical consideration for Medford ADU projects. Following the catastrophic 2020 Labor Day fires that destroyed Talent and Phoenix — communities just south of Medford — Oregon strengthened its Wildland-Urban Interface (WUI) construction standards. Many Medford properties, particularly on the city's eastern and hillside edges, are in designated WUI zones.

In WUI-designated areas, new ADU construction must comply with:

• Fire-resistant exterior materials: Ignition-resistant siding, roofing, decking, and eaves
• Ember-resistant vents and openings: Protected to prevent ember intrusion during wildfire events
• Defensible space: Vegetation management creating fire-safe zones around the structure (typically 30–100 feet from structure)
• Oregon WUI building code standards: Additional construction requirements mandated by Oregon law

Do not assume your property is not in a WUI zone — check specifically with Medford Planning or the Oregon Office of State Fire Marshal. WUI requirements add construction cost but are legally required and critical for safety.

Bear Creek and Rogue River Flood Zones

Bear Creek runs through Medford before joining the Rogue River to the north. Properties near Bear Creek, the Rogue River corridor, or other waterways may be in FEMA-designated flood hazard zones (Zone AE or other). ADU construction in flood zones requires:

• Elevated foundations at or above the Base Flood Elevation (BFE)
• Flood-resistant construction materials below the BFE
• FEMA floodplain permits in addition to standard building permits

Check your property's FEMA flood zone designation through FEMA's Flood Map Service Center or Medford Planning before designing your ADU.

Seismic Considerations

Southern Oregon, including the Medford area, has moderate seismic hazard. While somewhat distant from the highest Cascadia Subduction Zone coastal risk areas, new ADU construction must meet Oregon's seismic building code standards. DOGAMI provides region-specific hazard maps.

Permit Process

Oregon's statewide ADU framework is SB 1051 (2017) plus HB 2001 (2019) middle housing. HB 2098 (2021) is a rental-assistance bill, not ADU.

Contact: City of Medford Planning Department — (541) 774-2380 — medfordoregon.gov/planning

Disclaimer

ADU regulations in Medford — including WUI and flood zone requirements — are subject to change. Always verify current standards directly with the City of Medford Planning Department and Building Division and the Oregon Office of State Fire Marshal. This page is for informational purposes only and does not constitute legal or planning advice.