Permitting an Accessory Dwelling Unit (ADU)

An ADU in Berkeley, CA (credit: McDunn ADUs) This webpage provides general information about Denver's rules for accessory dwelling unit (ADU) permits. Please review this information before applying for your permits.

What is an ADU?

Examples of attached and detached ADUs

Accessory dwelling units (ADUs) are self-contained, smaller living spaces that are an extension of an existing property. They are often called mother-in-law suites, granny flats, casitas, backyard cottages, garage apartments, or basement apartments. An ADU has its own kitchen, bath and sleeping area, but is not considered a separate property that could be sold on its own.

ADUs take many forms. They can be built as a free-standing structure in the backyard, could be built above a garage, could be an addition built onto the main home, or could be a converted space within the main home, such as an attic or a basement. The choice of how and where to build an ADU will depend on the property owner's needs and construction budget as well as zoning and building codes.

Image: Examples of attached and detached ADUs

General Rules

  • ADUs must be built by a licensed contractor. Homeowners cannot apply for permits to build an ADU.
  • Only one ADU is allowed per Zone Lot (a buildable piece of land).
  • Mobile homes, recreational vehicles, “tiny homes” on wheels, and travel-trailers cannot be used as an ADU.
  • The Denver Zoning Code regulates the height, size, and placement of ADUs.  
  • An ADU must look “compatible” with the main house and must be smaller than the zoning allowance for the main house.
  • ADUs cannot be accessed by a separate driveway from that serving the main home, unless it is new access provided from an alley.
  • Where feasible, water, electric, sewer and other utilities should be provided from shared systems.
  • In single unit zone districts, the owner of the property must live on the property, either in the ADU or in the main house.
  • A Certificate of Occupancy is required before the ADU can be lived in.

See recent updates to zoning rules related to ADUs

Permits

Construction Permits

All new ADUs need zoning, building, and sewer use and drainage permits (SUDP). Projects that upload all of the information required for these three permit types (zoning, building and SUDP) with their initial online application can receive a simultaneous review.

Scroll down for a list of items to upload with your application.

Trade Permits

You will also need trade permits, such as electrical, plumbing, mechanical, and roofing permits. These can be applied for at any time, and in most cases, are issued online as quick permits. Find out what qualifies as a quick permit.

How to Apply using E-permits

Apply for permits online

First-time e-permits users will need to create an online account. Once signed into e-permits, go to "Apply for a Permit" under "Development Services."

For zoning, building, and SUDP permits: When prompted to select a permit type, select "building log." On the project details page of the application, under project information, select the following:

  • Project Classification: Single Family/Duplex Residential
  • Project Scope: New Accessory Dwelling Unit 

For quick permits (electrical, mechanical, plumbing, roofing): When prompted, select the appropriate permit type under "Quick Permits" and follow the prompts.

What to Upload with Your Application

Please upload these documents with your online application to receive building, zoning, and SUDP permits. 

Property Survey

This is only necessary if you are proposing construction within three feet of a property line. Please upload a boundary survey for vacant land or an improvement survey if there are existing structures.

Site Plan

Please draw the site plan to scale and include the scale and a north arrow on the plan. Please also include labels and dimensions for...

  • all zone lot lines (e.g., primary, side, rear)
  • adjacent streets and alleys
  • all existing structures and driveways already on the property
  • the proposed new ADU (include proposed height)
  • distances from the proposed new ADU to existing structures, lot lines, etc.
  • If a new driveway is proposed, please also include the location of the proposed driveways, dimensions from the driveway to the property line and any adjacent driveways, width of driveway, and material used in construction

For SUDP, please also include the size, type, and location of water, storm sewer, and sanitary sewer lines on your site plan.

Building Elevations with Dimensions

Please use the template provided below or submit scaled drawings.

Building Plans, Details, and Specifications

Please upload building plans that show the following:

  • Stud size and spacing
  • Rafter/truss size and spacing
  • Ridge board/ridge beam size
  • Collar tie size and spacing
  • Roof span
  • Foundation/slab details
  • Wall covering
  • Shear wall detail/anchor bolts
  • Header size, span, number of trimmers
  • Roof covering, pitch and overhangs
  • Wall and roof sheathing
  • Fire wall-rated projection detail and locations
  • Top plate and sill plate size and specifications
  • Ceiling height
  • Exterior materials with labels for each building component indicating color (non-paint) and finish
  • Manufacturer cut sheets for all materials, windows, siding and doors
  • Show window/door openings and major protrusions or indentations

View Sample Plans and Elevations

Special Situations

Landmarks and Historic Districts

All ADUs that are located in a historic district or a designated landmark will require a certificate of appropriateness, meaning the project's design has been reviewed by Landmark Preservation and is appropriate for the historic nature of the property. It is highly recommended that you obtain this certificate before applying for building and zoning permits.

Learn more about meeting design guidelines for landmark properties.

Parkways

If your property is along a designated parkway and the project encroaches on the parkway setback, you will need to download an Exception Request form (located under Contact the Parkways Team on the Parkways webpage) and email it to parkways@denvergov.org. 

Visit the Parkways webpage

Forestry

If there are trees located in the public right-of-way, or trees requiring protection in the primary street setback or side street setback, you will need to contact the Office of the City Forester at (720) 913-0651 or forestry@denvergov.org.

Learn more about forestry requirements. 

Research your property

Do I Need a Permit?

All accessory dwelling units (ADUs) need zoning, building, and sewer use and drainage permits.

Does My Zoning Allow ADUs?

Many mixed-use and residential zone districts allow ADUs. See if the zoning of your property allows ADUs.

 

If your zone district does not allow ADUs, you will need to apply to rezone your property. Learn about the rezoning process.

Ready to Apply?

Permits are issued electronically through the city's e-permits system.

 

Related Information

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