Accessory Dwelling Units

Accessory dwelling units (ADUs) are small independent residential dwelling unit located on the same lot as a principal one-family dwelling unit. Accessory dwelling units may be located within the principal dwelling unit, attached to the principal dwelling unit, or detached from the principal dwelling unit. 

Mobile homes, travel trailers, recreational vehicles, shipping 
containers, storage containers, and other such temporary structures shall be prohibited for use as an accessory dwelling unit.


How many Accessory Dwelling Units can I have, and how big can an Accessory Dwelling Unit be?
On properties with zoning that include single-family residential uses, property owners may have a maximum of one (1) Accessory Dwelling Unit. Accessory Dwelling Units are restricted to 50% of the principal dwelling unit’s footprint (excluding garage, porch, or similar areas) or 800 square feet, whichever is less.

How many people can there be living in an Accessory Dwelling Unit?
Regardless of the size of the unit, there is a maximum occupancy of two (2) people for an Accessory Dwelling Unit. The owner of the property must live in either the principal dwelling or the accessory unit. 

How will utilities be provided?
Accessory Dwelling Units must tie into the principal dwelling 
unit’s water and sewer connections, and will not require separate water or sewer taps, or water or sewer licenses. You will need to contact other utility providers for applicable telephone, television, electrical, gas and internet service to determine how those utilities can be served.

What if my principal dwelling unit uses an on-site wastewater treatment system (septic tank)?
If your home uses an on site septic system, you will need to coordinate with the Health Protection Division of Health and Human Services to determine if your on-site wastewater treatment system has adequate capacity or needs to be modified in order to accommodate the proposed Accessory dwelling Unit. They can be reached at or at (720) 887-2220.

What materials do I have to use for my Accessory Dwelling Unit?
Accessory dwelling units shall be designed to be consistent with the design of the principal dwelling unit. If the property is within a development that is subject to an applicable zoning or site plan document or code requirement that include design requirements for a single family residential units, the ADU shall be required to meet those design requirements. ADUs located in developments with no specific design standards shall be required to provide no less than 50% of the exterior wall surfaces in a material similar to the principal structure.

How many parking spaces do I need for an Accessory Dwelling Unit?
A minimum of one (1) off-street parking space shall be required for an accessory dwelling unit. Such parking is in addition to the required parking for the principal dwelling unit.

Does an Accessory Dwelling Unit need to meet setbacks?
Accessory dwelling units must meet applicable setback requirements for the zone district of the property.

Reviews and Permits Required
A building permit for Accessory Dwelling Units is required. Please use the General Permit Application form (available here). 
Contact the Building Division to determine what supporting documents will be required as part of your building permit submittal. Property owners will be required to record a declaration of use which will state the size and location of the accessory dwelling unit and shall reference that the accessory dwelling unit must remain in compliance with the regulations contained within the Municipal Code.

Please contact your HOA before submitting a building permit.