Accessory Units or ADUs

The Summit County Land Use and Development Code allows for accessory apartments, also known as  accessory dwelling units (ADUs), in certain zoning districts, with the requirement that they are rented to a member of the local workforce. Currently, accessory apartments require administrative review by the Summit County Planning Department before issuance of a building permit.

The Planning Department is in the process of modifying the regulations pertaining to ADUs to allow stand-alone, detached units and streamline the review and approval process. These amendments were approved on June 14, 2022.  For more information, see PLN21-074.

Accessory apartments are allowed as a permitted use only in single-family dwelling units in Summit County zoning districts, as specified in Figure 3-2 (pdf) of the Land Use and Development Code. Accessory units may be permitted in a PUD if this use was requested during the creation or modification of the PUD during the zoning amendment process.

Accessory apartments are governed by Section 3809: Local Residential Housing Summit County Land Use and Development Code.

If you are considering an Accessory Apartment or ADU, there are some important factors to evaluate prior to submitting an application. The Department has created a Quick Reference Guide & Checklist to help consider options. 

  • Covenant: 
  • Water:
    • If your property is served by a groundwater well, you may need to apply for water augmentation through the Colorado State Engineer.
    • If your property is connected to a water district, contact your water provider to inquire about availability and tap fees.
  • Sewer:
    • If your property is served by a leach field and on-site septic system, be aware that the system may need to be resized to allow for the Accessory Apartment. Contact the Summit County Environmental Health Department with any questions.
    • If your property is served by a sanitation district, contact the applicable district to inquire about sewer capacity and fees.
  • Access and Parking:
    • An accessory unit may only be permitted on a lot where the driveway conforms to current County standards. This includes but is not limited to: no more than one access point to the County road system (horseshoe driveways are not permitted); grade of no more than 8% for the first 25 feet from the roadway, and then no more than 10% thereafter; and widths at driveway flares shall be between 18 and 24 feet. Contact the Summit County Engineering Department for information about driveway standards.
    • There must be adequate on-site parking to accommodate an accessory dwelling unit and the main house – two spaces are required for the main house, and two for the accessory unit.
  • Building Code Standards
    • There are required standards concerning unit-to-unit separation that will be reviewed by the Summit County Building Inspection Department. These relate to fire and sound wall separation. This is an significant item to be aware of if you are considering installing an accessory unit in an existing home. Contact the Summit County Building Inspection Department with questions.

To begin the process of planning for the development of an accessory dwelling unit, contact the Summit County Planning Department at 970-668-4200 and the Summit County Housing Department at 970-668-4210.