Project Guide for Detached Dwelling Units

This guide is intended to provide you an overview of the permitting process for detached dwelling units or accessory dwelling units (ADUs) such as a guest house or carriage house that are detached from the primary residence and contain provisions for sleeping, cooking, and sanitation.  

NOTE:  A Certificate of Occupancy is required to complete the permitting process.

Help Me Get Started . . .

Before you start your project, you need to know what regulations apply to your property and what factors may impact your project. You'll need to consider:

Historic Landmark Status

If your property is in a local historic landmark district or is a designated landmark structure, the Landmark Preservation staff must complete a design review of your project before you begin. Use the DevelopDENVER tool to the right to determine your property’s landmark status. Changes to the exterior of landmarked properties require approval from Landmark Preservation prior to the issuance of appropriate zoning, building, curb cut, or revocable permits.   Visit the design review web page for more information.


Zoning establishes standards for things like the size and location of structures and acceptable uses for your property. Before you begin construction, you need to be sure your project is in compliance with Denver's Zoning Ordinance. Use the DevelopDENVER tool to the right to determine the zoning for your property. Once you've found how your property is zoned, you should look up your zone district in the Denver Zoning Code to see what that means for you.


Certain parkways and boulevards are specifically designated by ordinance to preserve their unique character. Each designated parkway has its own right-of-way width and regulations of setback distance of structures and signs. If you are unsure if you live along a designated parkway, use the DevelopDENVER tool to the right to determine your status.

Building Code

Denver Building Code provides minimum standards for building in order to safeguard public safety, health and welfare.

Location of Utilities

When designing your project, you need to know where utilities are located. You cannot build over existing utilities. Contact the Utility Notification Center of Colorado to mark underground utilities for your project. Call 1-800-922-1987 or 811 before you dig.

Location of Existing Sewer Lines

A plumbing contractor can help you locate the sewer lines on your property. If you plan to build a new structure over or within 2 feet of the existing sanitary sewer, you will need to replace the sanitary sewer with approved materials.

Contact the Department of Public Works at 303-446-3759 for more details.

NOTE: Wastewater Management defines an ADU as any structure that has either a bathroom or kitchen or is used as habitable living space.


Transportation review and approval is needed whenever you are changing the location of your driveway or proposing any improvements within the Right-of-Way (ROW) such as changing the curb cut.  All projects performed in the City Right-of-Way must be performed in full compliance with the City Charter, Ordinances, permitting processes and all other applicable standards, specifications and requirements of the City and County of Denver.

  • Landmark Certificate of Appropriateness - required If location is within a Landmark District or if you live in a designated landmark structure
  • Zoning Permit
  • #1R Construction Permit
  • #11 Forced-Air Furnaces, Ventilation and Air Conditioning and Gas Piping Permit 
  • #4 Plumbing Permit
  • #3 Electrical Permit
  • #2 Roofing Permit
  • Sewer Use and Drainage Permit (SUDP)
  • Parkways review - required if construction occurs in a parkway setback
  • Transportation review - required if there are proposed improvements in the Right-of-Way associated with this ADU or if there is a new or modified driveway connection to the street associated with the ADU.  See Project Guide for Driveways for more information.
  • Fire Prevention review
  • Right-of-Way (ROW) Permits - required for all proposed work within the ROW
    ROW improvements must be performed by a licensed contractor

For Landmark Certificate of Appropriateness:

If your property is historically designated or located in a historic district, you will need a design review of your project to obtain a Certificate of Appropriateness.  Visit the Design Review web page for more information.

For Zoning Permit:

A scaled or fully dimensioned Site Plan showing the following:

  • Address
  • Location of all existing buildings (shed, garage, carport, patio, etc.)
  • Location of proposed project
  • Location and size of footprint of all existing and proposed structures in relation to property lines on the lot
  • Property lines and relation to streets and alleys
  • Elevations - depending upon scope of work
  • Primary street setbacks of adjacent properties if proposed project is to be located on the front side of the property depending on the scope of work
  • Base Plane Information:  Original grade spot elevations at intersection of side property lines at front setback  and spot grade elevations at rear corners of property if within 2 feet of bulk plane and / or height.

Simple Project - One story, more than 5' away from property lines - only need site plan

Medium Project - Exactly 5' from property line and height within 2 ' of the bulk plane - need Site Plan and Elevation Plans with base plane information for height and bulk

High Project - Less than 5' to property line and/or the peak is perpendicular to the side property line - need the following:

    • Site Plan with base plane information for height and bulk
    • Elevation plans with base plane information for height and bulk

NOTE:  An Improvement Location Certificate can be used in place of a site plan in most cases. 




For Transportation:

Include in the Site Plan:

  • Existing and proposed driveways including dimensions (Required by Transportation if there is a proposed driveway)
  • Proposed improvements in the Right-of-Way Survey (Required by Transportation if there are proposed improvements in the Right-of-Way)
  • Tandem House Form

For Building Permits:

  • Floor plan with dimensions of each room
  • Foundation Plan including details on construction of the piers
  • Survey 
  • Soils Report 
  • Framing Plan  including size and spacing of post and beams
  • Roof framing
    NOTE:  If you are using roof trusses, keep the truss manufacturing specification on site for access by the building inspector. 
    NOTE:  If you are using dimensional lumber, provide the span, size, and spacing of the lumber.
  • #1R Building Permit - completed by staff of Development Services
  • #11 Forced-Air Furnaces, Ventilation and Air Conditioning and Gas Piping Permit (PDF)
  • #4 Plumbing Permit (PDF)
  • #3 Electrical Permit (PDF)
  • #2 Roofing Permit (PDF) 
  • Notification Letter



For Wastewater Sewer Use and Drainage Permit (SUDP): 

  • Utility Site Plan that includes the following:
    • Location of structures in reference to property lines
    • Sewer locations
    • Pipe sizes
    • 2-way cleanouts
    • Material for all existing and proposed structures from point of connection to the structure to the main
    • Water line locations with sizes
    • All existing and proposed underground and storm water/sewage drainage.

Wastewater does require sewer replacement with approved material for any structure being built over or within 2' of the existing sewer line.

Wastewater does require that historic storm drainage be maintained and not directed to adjacent properties or across public sidewalks.

If property is in a floodplain, additional submittal requirements apply.

For application, guidelines and other specific information, see the following:

Sewer Use and Drainage Permits (SUDP)


  • Address Assignment Card - Accessory Dwelling Units (ADUs) require a separate address.  Address must be issued or verified by Development Services staff  at the front counter or by Public Works staff on the 5th floor.


For a Do-It-Yourself (DIY) Project:

  • Homeowners Exam for specific trade if completing the work yourself 
    (See DIY Projects for requirements and more information.)
  • Identification (i.e. Driver's License)

Estimate Fees

Zoning and Building permit fees are based on valuation of the work to be completed including the labor and materials.   

For sewer use and drainage permits, there is a $100 application fee, plus appropriate fees shown on the current permit fee schedules (see "Public Works / SUDP") based upon the use of the accessory dwelling unit. The fees change yearly.  Fees for sewer use and drainage permits will depend on whether or not your property is eligible for tap credits (usually applies when you have an existing tap). Exact fees and credits are calculated during the permit review. 

There are no fees for Transportation, Parkways or Landmark review.

ROW permit fees are based on the amount of work constructed and the amount of time they are occupying the ROW. 

Pay Fees

Fees can be paid in person at our office on the 2nd floor of the Wellington Webb Building or by mail:
Development Services
Wellington Webb Municipal Building
201 W. Colfax Ave., 2nd Floor
Denver, Colorado 80202
We accept Visa, MasterCard and Discover Card, cash and personal checks at our counter.

For Landmark Approval:

Submit a design review application to Landmark Preservation.  The approval typically takes one to three weeks. More complex projects or projects requiring Landmark Preservation Commission or Lower Downtown Design Review Board approval will take longer.

NOTE:  Obtain Landmark approval first before proceeding with other permits.


For Zoning and Building:

Plan Review - Submit all construction documents at the Permit Service Counter for review by City staff. Once review has been completed and all documents approved, permits will be issued.

Adjacent Property Owner Notification:

Where the project requires any type of demolition or excavation, builder must verify notification of all adjacent property owners by providing the City either the return receipt of certified mail delivery, or the signed receipt of personal notification.

Please note that  a permit will not be issued until 10 working days has passed since the adjacent property owner notification was made.


For Wastewater Sewer Use and Drainage Permit (SUDP):

Plan Review - Submit your plans in person or use e-Plan to submit your plans electronically for review by City staff. Once review has been completed and all documents approved, permits will be issued.


For Parkways Review:

Plan Review - If Parkways review is required, submit all construction documents at the Permit Service Counter for review by City staff. Once review has been completed and all documents approved, permits will be issued. The review process can take up to 30 days depending upon the complexity of your project.


For Transportation Approval:

No separate submittal is required.  Docuemnts can be submitted at the same time as the Zoning, Building and Parkway review.


For Right-of-Way Permits:

Licensed contractor can obtain the ROW permits at Public Works Permit Operations at 2000 West 3rd Avenue or directly from the ROW inspector at (303) 446-3469.

All approved construction set of documents, permits and inspector signature card are to be available on site upon request.

Typical inspections during construction of accessory dwelling units include the following:



  • Pre Construction Meeting
  • Temporary Service 
  • UFER
  • Footing
  • Foundation Wall and Foundation Perimeter Drain
  • Waterproofing
  • Frost Wall Insulation
  • Water Service
  • Underground Utilities (Electrical, Mechanical, Plumbing)
  • Setbacks
  • Bulk Plane Inspection
  • Exterior Sheathing
  • Rough Utilities (Electrical, Mechanical, Plumbing)
  • Frame
  • Roofing
  • Exterior Lath
  • Insulation (Batt and Blown)
  • Drywall
  • Blown Insulation
  • Pressure Test 
  • Final Utilities (Electrical, Mechanical, Plumbing) 
  • Temporary Certificate of Occupancy
  • Certificate of Occupancy
  • Final construction inspection
  • Zoning inspection


Wastewater Inspections:  

  • Wastewater inspection for new, replaced, or rerouted sanitary sewer
  • Wastewater review for storm sewer/drainage work as called out on permit
  • If construction occurs in a floodplain, additional inspections are required.
  • Wastewater final inspection - consists of inspection of the 2-way cleanouts and all storm sewer work and storm drainage from grading, downspouts, and storm work
  • Only a licensed contractor can call for an inspection.


For Right-of-Way:

  • Construction Engineering will inspect work performed in the ROW and check to see if ROW infrastructure was damaged during construction.


NOTE:  The inspections listed above may vary depending on the complexity of your project. 

  • Please be aware that the ROW inspector may require the replacement of any damaged infrastructure (i.e. sidewalk and curb and gutter) in the ROW adjacent to your site. 
  • Section 49-551.1 of the Denver Municipal Code states that the property owner or lessee of any real property is responsible for the continuing care, maintenance, repair, and replacement of all improvements installed in the public ROW between the property line and the curb line adjoining their property.
  • Please take care not to damage the ROW infrastructure during the construction.

Who Will Be Doing the Work?

Decide whether you plan to complete the project yourself or hire a licensed contractor to complete the job for you.

Do It Yourself

Do-It-YourselfYou may need to pass a Home owners exam  to demonstrate proficiency in specific trades in order to get a permit to do the work yourself. 

You will also need to meet a set of requirements established by the Denver Building Code and the Building Department Policy ADMIN 131.3 governing homeowner completed work.  This policy can be found on our Building Codes, Forms and Policies page. 


Contractors Use the Contractor license search to see if your contractor has obtained a contractor's license from the City and County of Denver. 


To view other considerations, see our Doing the Work Yourself page.

Home Projects

Every project is different.  Depending upon the complexity of your project, the permit requirements and inspection process may vary from the information presented in this guide.  If you have any questions, please contact us.


What you need to know for your project!

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