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Design Review for Accessory Dwelling Units (ADUs)

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Landmark Preservation reviews applications for accessory dwelling units on all Denver landmarks and historic district structures. Applications are reviewed for consistency with the appropriate design standards and guidelines. Please read the following instructions carefully to ensure timely design review of your project.

Before you begin . . .

The following materials are not allowed for accessory structures in historic districts or on individual landmark properties:

  • Composite-wood siding, T-111 siding, molded plastic siding, vinyl siding, and aluminum siding
  • One- or two-coat stucco 
  • EIFS
  • Materials with a faux-wood grain texture
  • Vinyl windows 
  • Windows with internal muntins or glued-on muntins. Windows may be simulated-divided light with muntins on the exterior and interior faces of the glass, but must include a spacer bar.

For more information about appropriate materials, please review the design guidelines in Step 1.

1 - Determine which design guidelines apply

Your location and type of project determines which design standards and guidelines you should follow. If you are unsure about whether your project is in a historic district, check the landmark and historic districts map.

In certain neighborhoods and historic districts, additional design guidelines may apply.

2 - Schedule a pre-application meeting

Accessory dwelling units are subject to review by the Landmark Preservation Commission and require a pre-application review meeting. 

To request a meeting, please submit the pre-application review form (PDF) and all required information to Landmark Preservation staff via email (

3 - Arrange RNO meeting (if applicable)

Projects in historic districts where an RNO has completed design review training must present infill proposals to the RNO before a complete application may be submitted for review by the LPC. Landmark staff will let you know if there is a qualifying RNO in place and, if so, make the referral at the time of your pre-application meeting.

For more information, download the Registered Neighborhood Organization policy (PDF).

4 - Collect submittal materials

Design review applications must adequately describe the project and provides sufficient information to evaluate the proposal. Documentation must clearly illustrate the existing conditions as well as any proposed alteration(s).

All applications for accessory dwelling unit design review must include the following information:

Please click the submittal elements for downloadable materials and additional information. To avoid delays, please only submit complete applications.

Photographs of existing conditions showing proposed building site and surroundings are required and must be:

  • In color
  • Labeled with direction and orientation to the street
  • No smaller than 4"x6" in size (or between 1024 x 768 pixels and 1280 x 960 pixels)
  • Arranged on one or more sheets within the drawing set (PDF format)

For examples of acceptable photos and tips for taking good photos, download Landmark Standards: Photographs (PDF) and the Photo Page Example (PDF).

All projects must submit a dimensioned and scaled site plan including:

  • Street address
  • North arrow
  • Scale (plans must be drawn to a measurable scale)
  • Location of streets, sidewalks, alleys (any right-of-way or easement), property lines, and all existing structures
  • Location of existing and proposed fences, retaining walls, exterior stairways and ramps, driveways, mechanical equipment, etc.
  • Front setbacks of adjacent properties
  • Original grade elevation at intersection of side property lines and minimum setback
  • Spot grade elevation at rear corners of property
  • Primary street setbacks of adjacent properties (the distance from the front property line to the face of the enclosed area, not porch or awning)

sample site plan

Submit elevation drawings of each proposed façade that include the following:

  • Street address
  • Façade direction
  • Scale (plans must be drawn to a measurable scale) 
  • Major dimensions 
  • Proposed architectural materials 
  • All proposed work (additions) 
  • Height of adjacent structures

All projects must submit proposed floor plans and roof plan, which must:

  • Be drawn to scale (1" = 40' or larger, if possible) 
  • Include all levels/floors 
  • Use simple room labels (bedroom, bathroom, etc.) 
  • Not include furniture

The following details of construction are required:

  • Enlarged elevations and sections for each window type and location, showing the full window in the wall assembly, including head, jamb, sill, muntins and other details/profile information. 
  • Samples/boards of all exterior materials with labels for each building/building component indicating material and finish. A photograph of the sample board must be provided to Landmark staff.
  • Manufacturer cut sheets on all products, including wall cladding, roofing, windows, doors, and lighting.
  • For glass, provide visible transparency ratings of glass.

Submit Your Application

Complete the required application and submit it, along with any supporting materials, by email to  Your submission should include two attachments:

  • PDF with the completed form ("yourname-app.pdf") 
  • PDF that combines all supporting materials ("yourname-app-materials.pdf")

File size should not exceed more than 25 MB combined. Contact us if you are having trouble with your electronic submission.

Every project is different. Depending upon the complexity and specifics of your project, process and time frame may vary from the information presented on this website and in the application materials. If you have any questions, please contact us.

NOTE: All materials submitted with your application become the property the City and County of Denver. The materials are part of public record, can be used in a public hearing, and cannot be returned.

5 - Staff review, revision and LPC presentation 

The Landmark Preservation Commission reviews all proposed accessory dwelling units on individual landmark properties and properties in historic districts. 

LPC review will result in approval, approval with conditions, continuance or denial.

Projects that are approved with conditions must submit the requested adjustments to the final construction drawings to landmark staff before a certificate of appropriateness will be issued.

Projects that are continued must provide additional information as requested by the LPC, and must return to the LPC for approval.

Projects that are denied must go before the LPC again with a revised submittal that addresses the LPC's comments.

6 - Certificate of Appropriateness issued

Once the ADU has been approved by LPC, landmark staff will issue a certificate of appropriateness and stamp the drawings.

The certificate of appropriateness and stamped drawings must be included with plans and materials submitted to Development Services when applying for building or zoning permits. If drawings submitted for a building permit vary in any way from the stamped drawings issued by Landmark staff, the permit drawings will need to be revised or the Landmark stamped drawings will need to be revised. If drawings submitted for a building permit vary substantially from drawings approved by staff or LPC, the project may need to return to the LPC for approval. During the inspections process, the completed project must match the work shown on the Landmark-approved stamped drawings. 

Please coordinate with landmark staff on any changes.