Research Checklist - Accessory Dwelling Unit (ADU)

Summary

The process for acquiring the necessary permits is extensive. It is highly advised that you contact staff prior to applying for permits to verify. For commonly asked questions click here to navigate to the FAQs section.

ADU Zoning Code: DCC 18.116.355

Potential List of Permits needed for ADU:

Site Evaluation Permit
Planning ADU Permit
Onsite Permit (New Installation)
Driveway Access Permit (if applicable)
1 & 2 Family Dwelling OR Structural Permit with Supplemental Permits (Elec/Mech/Plumb permits)

If you are building in the city limits of Sisters or La Pine, you will need to contact those planning departments.

Step 1 – Preliminary Requirements

Verify your property is 2 acres or more, or if you’re in the South Deschutes County area a minimum of 5 acres. See the ADU 5-Acre Minimum Map located here: ADU 5 Acre Minimum
Verify the property is located in one of the following zones: RR-10,MUA-10, UAR-10, SR-2/12 AND WTZ. Retrieve the Summary Property Report to view the zoning and acreage of your property located here: CDD Summary Report
Complete the Basic Zoning Checklist
Verify the Fire Hardening Requirements
Contact Your Utility Provider ( Water, Electric, & Gas ) to verify if the potential ADU can be serviced
Verify Fire Protection District Adequate Access and ADU Driveway Access Requirements (different than Driveway Permit)

Step 2 - Contact Planning Staff

Once you have completed the Basic Zoning Checklist (see above), confirm that your property can qualify for an ADU with staff. Contact the Planning Division using the Ask a Planner online form, email planning@deschutes.org, or call 541-388-6560.
Although not required, we advise that you consider a Pre-Application Meeting to ensure that your project will be successfully permitted from start to finish. Fill out the Pre-Application Request form here.

Step 3 – Apply for Permits

Once you have successfully completed Steps 1 and 2, staff will advise you on next steps to apply for permits.

Onsite
- Site Evaluation Permit
Planning
- Planning ADU Permit - At this time you can apply for the Onsite Permit (New Installation)
- Property owners, or their authorized representatives, can submit a land use application in one of three ways. Learn more about it here.
Onsite
- Onsite Permit (New Installation) – If applicable, upon application of Planning ADU Permit
Driveway Access
- Driveway Permit - If there is not an approved Driveway Permit for your property, you will be required to apply for a Driveway Permit. This is applicable for 1 & 2 Family Dwelling and Structures.
Building
- 1 & 2 Family Dwelling OR Structural Permit with Supplemental Permits (Elec/Mech/Plumb) - When concurrently building a new primary residence and a new ADU, you will need to apply for two 1 & 2 Family Dwelling Permits (DWL); one for the primary residence and one for the secondary residence. Use the table below for help on selecting the correct permit type to apply for. For any scenario that does not meet the matrix feel free to reach out to staff.

Building Permit Matrix for ADU
ADU Type	New	Conversion
Detached	1 & 2 Family Dwelling (-DWL)	Structural Permit (-STR)
Attached	1 & 2 Family Dwelling (-DWL)	Structural Permit (-STR)
Interior (Upper Level)	n/a	Structural Permit (-STR)
Interior (Lower Level)	n/a	Structural Permit (-STR)
Above Garage	n/a	Structural Permit (-STR)
Garage Conversion	n/a	Structural Permit (-STR)
This table is for help on selecting the appropriate Building Permit type. For any scenario that does not meet the matrix reach out to staff.

Frequently Asked Questions

Can more than one ADU be established on a property?

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.

Category: ADU

Are variances available to any of the specific ADU standards such as siting requirements, square-footage requirements, etc.?

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.

Category: ADU

Can an ADU be built in the Exclusive Farm Use (EFU) or Forest Use (F1, F2) Zones?

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.

Category: ADU

What is the difference between a guest house and an ADU?

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.

Category: ADU

Can a property owner build an ADU themselves?

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.

Category: ADU

Will Deschutes County have any pre-approved plans for ADU development?

At present, Deschutes County does not anticipate the adoption of any specific pre-approved building plans for ADUs.

Category: ADU

What is the process for converting an existing residence to an ADU and adding a new primary residence?

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.

Category: ADU

Are ADUs permitted to have attached garages?

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.

Category: ADU

How will the 900-square-foot "useable floor area" standard for ADUs be measured?

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.

Category: ADU

How will the 100-foot siting distance standard for ADUs be measured?

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.

Category: ADU

Will a separate address be needed for an ADU?

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

Category: ADU

If an existing septic system isn't adequate for adding an ADU, is it necessary to expand or improve the existing system or will adding a second system be required?

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

Category: ADU

How long does it typically take for a septic site evaluation from the date of initial application?

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.

Category: ADU

Are ADUs allowed in unincorporated communities such as Tumalo or Terrebonne?

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.

Category: ADU

What if there is a discrepancy between Deschutes County’s referenced property size and a recorded survey?

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.

Category: ADU

How do the state wildfire hazard mitigation standards approved by Senate Bills 762 and 80 affect ADU development?

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.

Category: ADU

For properties subject to additional wildfire mitigation standards, when converting an existing structure to an ADU, will the siding, roofing, and other materials need to be replaced to meet the fire hardening requirements?

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.

Category: ADU

When will the Statewide Wildfire Hazard Map be released?

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.

Category: ADU

Can manufactured homes be used as an ADU?

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.

Category: ADU

How will property taxes for ADUs be handled?

All property tax information is handled by the Deschutes County Assessor’s Office: https://www.deschutes.org/assessor

Category: ADU

Can ADUs be rented on a short-term or long-term basis?

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.

Category: ADU

Will a lot of record verification be required to construct an ADU?

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.

Category: ADU

Will ADUs be subject to the standards of Deschutes County's Combining Zones (Landscape Management Zone, Wildlife Area Zone, etc.)?

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.

Category: ADU