Accessory Dwelling Units (ADUs)
Starting December 1, 2023, Accessory Dwelling Units (ADUs) can be permitted in certain zones in rural Deschutes County.
To confirm if your property qualifies for an ADU please contact the Planning Division using the Ask a Planner online form, email planning@deschutes.org, or call 541-388-6560. If you would like to research the key zoning qualifications prior to speaking with a Planner use the Basic Zoning Checklist link below.
The new ADU zoning codes can be viewed here.
On November 30, 2023, Community Development Department staff hosted a public information session for anyone interested in learning more about rural ADUs. A recording of that session can be located here and a copy of the presentation can be found here.
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Step 1 Site Research |
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Step 2 Site Design |
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Step 3 Permitting Process |
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Step 4 Construction & Inspections |
Frequently Asked Questions
Eligible properties are limited to a single ADU onsite. When establishing an ADU, if a property already contains a lawfully established guest house, temporary hardship dwelling, or similar secondary residential use, they will be required to convert eligible structures to an ADU or to an accessory building which does not contain living quarters through the development review process.
Deschutes County cannot offer variances to any requirements outlined in Oregon State Statute (ORS), which include ADU provisions such as the number of allowed ADUs, siting standards, square-footage limitations, and various other criteria.
Pursuant to Oregon State Statute (ORS), ADUs are specifically limited to rural residential exception areas, which does not include resource zones such as the Exclusive Farm Use (EFU), Forest Use (F1, F2), or Open Space and Conservation (OS&C) Zones.
Guest houses are a distinct use category in the Deschutes County Code. Guest houses are defined as “living quarters within a detached accessory building located on the same lot as the main building for use by temporary guests of the occupants of the main premises, not rented or otherwise used as a separate dwelling. A guesthouse shall contain no kitchen, kitchenette or other cooking facilities.”
Guest houses are not allowed in all zones and are subject to separate land use, building safety, and onsite wastewater standards from those governing ADUs. Additional questions concerning guest house development should be directed to the Deschutes County Planning Division.
A property owner may do the framing, plumbing, and mechanical work themselves. A property owner may not install, extend, alter, or repair any LP gas appliance or piping, vent or flue connection related to or in connection with LP gas installations, unless the property owner has received an LP gas installation license from the State Fire Marshal. A property owner may not perform the electrical installation if the ADU is for rent, lease, sale, or exchange.
At present, Deschutes County does not anticipate the adoption of any specific pre-approved building plans for ADUs.
The conversion of an existing residence to an ADU must be completed simultaneously with the permitting process to construct a new residence. The existing structure must meet all the relevant planning, onsite wastewater, and building requirements. All necessary conversion permits must be finalized during the new primary dwelling review. Applicants should be aware that depending on when and how the original residence was constructed, there may be additional challenges and expenses associated with residential conversions to meet all relevant ADU standards.
Based on the current provisions in Oregon State Statute (ORS), only detached structures sharing no common wall with the primary dwelling can be utilized as an ADU.
Yes, Deschutes County Code allows an attached garage space in addition to an ADU which does not count towards the 900-square-foot "useable floor area" regulation. Attached garages do not have specific size limitations, but development plans will be considered on a case by case basis. Attached garages cannot contain separate rooms or partitions which could be confused for additional living spaces. Garages can contain certain appliances such as washing machines and dryers, but cooking facilities are not allowed.
Oregon State Statute (ORS) and the Deschutes County Code requires that lawfully established ADUs must contain no greater than 900-square-feet of “useable floor area,” measured as follows:
- One Story Structures: The footprint of the entire ADU structure, minus non-"useable floor area" components such as attached garages, decks, or porch covers. Outside these specific exemptions, no additional components of ADUs will be exempted from the “useable floor area” measurement.
- Two Story Structures: The footprint of the entire ADU structure, plus the stair area for the first floor, minus non-"useable floor area" components such as attached garages, decks, or porch covers. Outside these specific exemptions, no additional components of ADUs will be exempted from the “useable floor area” measurement.
Oregon State Statute (ORS) and the Deschutes County Code requires that lawfully established ADUs must be located no farther than 100 feet from the primary dwelling, measured as follows:
- For new ADU construction: This standard will be measured from the nearest portion of the primary dwelling to the nearest portion of the "useable floor area" of the ADU.
- For lawfully established pre-existing structures which are converted to an ADU: This standard will be measured from the nearest portion of the primary dwelling to the nearest portion of the ADU, including non-"useable floor area" components of an ADU, such as attached garages.
Yes, ADUs will be required to utilize a separate address for emergency services. Additional information concerning addressing can be located at: https://www.deschutes.org/cd/page/addressing
In most cases, the existing septic system has likely been sized to serve only the existing residence onsite. To construct an ADU, the existing system must be upgraded or a new separate system must be installed. Modifying existing systems is often complicated and may not be feasible, so a separate system may be the preferred option. In all cases, applicants will be required to apply for a septic site evaluation prior to submitting a formal development application for an ADU. Please contact the Deschutes County Onsite Wastewater Division for additional details: https://www.deschutes.org/cd/page/onsite-wastewater-treatment-systems
Site evaluations typically take approximately 4 weeks, depending on weather and staff capacity. Winter weather can delay site evaluations because of snow cover or frozen soil.
Pursuant to Oregon State Statute (ORS) and the Deschutes County Code, ADUs will only be allowed within rural residential exception areas, which do not include unincorporated communities such as Tumalo, Terrebonne, or Sunriver. Additional development opportunities may be available in these areas contingent on individual site characteristics, zoning standards, and onsite wastewater requirements.
In general, the Planning Division will rely on DIAL, the Deschutes County online property information resource, for official determinations regarding property sizes. However, if an applicant has supplementary information such as a survey filed with the Deschutes County Surveyor’s Office which shows differing property sizes, they are encouraged to present that information to the Planning Division for consideration. Ultimately, any decisions regarding discrepancies on property size from the information listed on DIAL will be considered on a case by case basis.
Prior to release of the Statewide Wildfire Hazard Map by the Oregon Department of Forestry (ODF), all ADUs must meet additional fire hardening building standards as identified in Section R327 of the Oregon Residential Specialty Code (ORSC) and additional defensible space standards as identified in the Deschutes County Code or in consultation with the relevant fire protection district for the property.
After release of the Statewide Wildfire Hazard Map, only those properties identified as having a "high hazard" and/or located within a "wildland urban interface (WUI)" will be subject to additional mitigation standards.
Conversion of an existing structure to an ADU will depend on how the existing structure was built as some materials and features may already comply. Those features that do not comply must be altered or replaced to comply with the ORSC R327 Fire Hardening Requirements. This requirement is also applicable when converting an existing manufactured home to an ADU.
The process to adopt a new version of the Statewide Wildfire Hazard Map is currently underway, however it is unclear when this will be completed. The Oregon Department of Forestry (ODF) and the Oregon State Fire Marshal have indicated that a final version of the map may be available in late 2024.
If the manufactured home meets all the relevant ADU requirements included in the Deschutes County Code, including the fire hardening requirements as identified in Section R327 of the Oregon Residential Specialty Code (ORSC) in those areas where it is applicable, it may be an option. Prior to release of the Statewide Wildfire Hazard Map by the Oregon Department of Forestry (ODF), all ADUs must meet additional fire hardening building standards. Applicants will need to provide documentation that shows the proposed manufactured home complies with the ORSC R327 Fire Hardening Requirements. A building plan review will be required to confirm fire hardening compliance.
All property tax information is handled by the Deschutes County Assessor’s Office: https://www.deschutes.org/assessor
Properties owners can utilize an ADU on a long-term rental basis. However, pursuant to Oregon State Statute (ORS) and the Deschutes County Code, property owners who establish an ADU will be prohibited from utilizing either the primary dwelling onsite or the ADU as a vacation rental. Vacation rentals are defined as units which meet all the following characteristics:
- The occupant rents the unit for vacation purposes only, not as a principal residence; and
- The occupant has a principal residence other than at the unit; and
- The period of authorized occupancy does not exceed 45 days.
To qualify for ADU development, properties must be verified as legal lots of record. Many properties were created as part of lawfully established partitions or subdivisions, and as such constitute legal lots of record. Additionally, other properties may have previously gone through a formal lot of record verification process with the Deschutes County Planning Division. However, some properties may have unclear creation history and may be required to apply for a formal lot of record verification prior to development of an ADU. Please contact the Deschutes County Planning Division for specific information and details regarding individual properties.
Pursuant to the Deschutes County Code, ADUs will be subject to any relevant Combining Zone standards associated with the property in question. Development within designated Combining Zones may require supplemental land use review from the Deschutes County Planning Division in addition to the underlying ADU development review.
Supporting Documents
ADU Basic Zoning Checklist (122 KB) ADU Fire Hardening Requirements (197 KB) ADU Driveway Access Requirements (375 KB) ADU Fire District Access Form (81 KB) ADU 5-Acre Minimum Lot Size Area Map (204 KB) 
