Accessory Dwelling Units

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This page contains information about the current requirements for Accessory Dwelling Units. The City is proposing a change in City ordinance to expand the use of ADUs. The proposal would expand this use to single-family residential zoned areas.

View Proposed Expansion for ADUs

Current Information

Within certain residential zones, an Accessory Dwelling Unit (ADU) is permitted. An ADU must be subordinate in size to the principal residence and must comply with additional height, size, and location restrictions.

Permitted Zones

Detached ADUs are permitted within the R2, R4, R5, SU, and C5 zone districts. To find the zoning of your property, consult Property Zoning.

The property must meet the minimum lot size required for two-family residential use. In the R2 zone, that minimum size is 7,000 square feet, while in the R4, R5, SU and C5 zones, the minimum lot size is required to be 6,000 square feet.

Maximum Size

Size is regulated by a number of City Code provisions. The most specific provision allows a maximum footprint or finished living area (whichever is greater) of 750 square feet; decks and/or porches are not considered to be living area for purposes of this calculation.

The size of the ADU also cannot be greater in gross floor area than the size of the footprint of the principal structure. That is, if the principal residence measures 600 square feet in footprint, a maximum of 600 square feet of accessory structure would be allowed.

Finally, the total allowable lot coverage specified by the zone district restricts the size. For more information on lot coverage and other residential development standards, consult Property Zoning of contact the Land Use Review Division.


As with almost every structure, ADUs are required to meet certain setbacks. First, ADUs must be constructed entirely within the rear 50 feet of the property. Second, they must maintain a minimum five (5)-foot setback from the rear property line. This setback is required to be a minimum of 10 feet if the ADU is atop a garage with doors that face the alley.

The ADU must also be located behind the rear corners of the principal residence and must maintain a 20-foot setback from the principal residence. Finally, the ADU must meet side yard setbacks specified by the zone district.

Other Requirements

In addition to setbacks and lot size requirements, ADUs must comply with a height restriction of 25 feet. The height of accessory structures is measured from the average grade (unless the property is located within the Hillside Overlay zone) to the peak of the roof.

ADUs must also provide adequate off-street parking for residents. A minimum of one (1) parking space shall be required in addition to any existing parking spaces at the time the application for an ADU is made.

Additional Information:

For Building Code requirements, contact the Regional Building Department at (719) 327-2880. The Department is located at the Pikes Peak Regional Development Center, 2880 International Circle, in Colorado Springs.