FAQs: Accessory Dwelling Units

The main difference between an internal, attached, and detached accessory dwelling unit (ADU) lies in their location relative to the primary residence.  

Internal ADU: This type of unit is a form of an attached ADU, that is within the existing primary dwelling (i.e. the main house) and is typically located in the basement or attic. 

Attached ADU: This type of unit is physically connected to the main house, typically sharing a wall, roof, or foundation. It can be an extension of the existing structure or converted space, such as a basement, garage, or attic. Because it's attached, it often shares utilities with the main house. 

Detached ADU: This unit is a completely separate structure from the main home. It is typically located in the backyard or on a separate portion of the property, offering more privacy and independence from the primary residence. Detached ADUs are often built as stand-alone buildings and might have their own utilities. 

Currently, ADUs are permitted in three zone districts: OA-R1, OA-R2, and OA-RMU. The amendment of the code will result in ADUs being permitted in nine zone districts: R-R, R-1, R-2, R-3, R-4, OA-R1, OA-R2, MU-A, and APZ. 

Elements of the amendment required by the bill that cannot be modified by the Aurora Planning and Zoning Commission and the Aurora City Council include: 

• Allowing for one ADU where single family detached units are allowed 
• Having administrative approval process for ADUs 
• Not requiring parking or owner occupancy (with limited exceptions) 
• Allowing certain ADU sizes and setbacks 
• Not restricting ADUs through design and dimensional standards that are more restrictive than those that apply to single family homes in the same district 
• Requirements in the law also apply to planned developments (PDs) and homeowner’s associations (HOAs) within subject jurisdictions