Accessory Dwelling Units (ADUs)

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ADUs

You have decided to build a detached accessory dwelling unit (ADU), such as a guest house, on your property. If you drive the alleys of Curtis Park, you will see many early brick 1- to 2-story carriage houses. Continuing the neighborhood’s historic pattern of secondary structures, the city has adopted a special zoning overlay called the Curtis Park Conservation Overlay District (CO-2) which allows most property owners in Curtis Park to add an ADU onto their properties.  The zoning parameters for ADUs are found in Section 9.4.3.7 of the Denver Zoning Code.

If your property is within the locally-designated Curtis Park Historic District boundaries, you will need:

  • City permits, and

  • Historic design review approval from Denver Landmark Preservation before beginning work, and

  • A meeting with Curtis Park Neighbors Design Review Committee prior to scheduling your project before the Denver Landmark Preservation Commission  

If you are planning a new garage (auto use only) or new infill construction (a new house on a vacant lot), go the Denver Landmark Preservation website or contact Denver Landmark Preservation for guidance.  

Navigate the 5 questions below to find out the steps needed to complete an ADU in Curtis Park.   

1. Is my property in the Curtis Park Historic District?  

Check this website or type your address into the Denver Landmark finder to discover whether your property is  within the Curtis Park Historic District (a-h).   Historic design review is required both for contributing (or historic) and non-contributing properties (non-historic) in the historic district, although the design review processes may differ.  To find out if your property is contributing or non-contributing to the historic district, contact Denver Landmark Preservation.  

2. What makes my house historic?

If your house is contributing to the Curtis Park Historic District, it is a “historic” home.   To determine what makes your home “historic,” figure out what are the character-defining features that make your home one-of-a-kind, such as its key building materials and architectural style.  Owners of both historic and non-historic homes should peruse the Character-Defining features for Curtis Park to determine how your home fits into the historic district.  It is important to plan new construction such as an ADU to respect the unique character of a historic home and to be compatible with the historic neighborhood.

3. Are city permits required for my project?   

Yes.  All ADUs require both a city building and zoning permit.  

4. Is historic design review required?

Yes. You will need to set up a pre-application meeting with the city’s landmark preservation staff early in the design process to provide guidance on the size, shape and design options for an ADU that will fit the character of the historic house on the property and the surrounding historic district.  All ADUs will require review and approval by the Denver Landmark Preservation Commission. To learn more about the city’s historic design review process, click here.   You are more likely to obtain city design review approval, if you plan a project that respect’s the character-defining features of your house and the Curtis Park Historic District.   

5. How can I ensure my project obtains design review approval?

Contact the knowledgeable Curtis Park Neighbors Design Review Committee for advice and ideas. For the best possible results, plan your ADU to respects the character-defining features of your house and property, and:

  • Locate the ADU on the rear of the lot next to the alley where it is not highly visible from public streets. Check with zoning on placement since setbacks for ADUs are different than garages.

  • Choose a boxy, rectangular shape with a flat, gabled or hipped roof, similar to historic carriage houses in Curtis Park.

  • Size the ADU smaller than the existing house if possible, so that the main house remains visually prominent on the lot. ADUs are best not seen from the street.

  • Design the new ADU:

    • To be similar in size and height to historic carriage houses within your block

    • To be below the highest point of the existing house on the lot

    • To a recommended height of 20’ if using a flat roof

  • For lots with single-story houses, if a two-story ADU is planned:

    • Design the ADU’s building footprint to be smaller than the main house

    • On street visible elevations, use matching materials to the house (typically brick) to help the taller ADU blend in with the one-story house

    • If using a flat roof, a height of 20’ is recommended

    • Use brick on street-facing or visible elevations

  • Clad the ADU with materials already present on your house, such as brick or wood siding. For larger ADUs or ADUs with high street visibility, such as corner lots, use brick cladding on street visible elevations.

  • Keep it simple.  If your house is historic, design the ADU to follow the existing styling of your home but simplify the details, such as decorative trim, so that the new construction is visually distinguished from the historic home.  For non-historic houses, use a simple design and materials common to the neighborhood, so that the ADU is compatible with the surrounding properties.

This web content was added in 2019, and is accurate to the best of our abilities. Contact Denver Landmark Preservation for the most up-to-date and accurate information on the city's design review and permit requirements.