Ready to build an ADU in Denver? You’ll need to know about permitting first. Learn more about the process and regulations here.
What Are Denver Permitting Rules for ADUs?
Denver has standardized its zoning to allow ADUs in nearly all residential areas. However, just because ADUs are allowed doesn’t mean there aren’t rules or regulations.
Currently, Denver ADU rules include:
Size Limits: The maximum footprint depends on your lot size:
- If your lot is less than 6,000 square feet, your max ADU size is 650 square feet.
- If your lot is between 6,000–7,000 square feet, your max ADU size is 864 square feet.
- If your lot is more than 7,000 square feet, your max ADU size is 1,000 square feet.
Height & Stories: Detached ADUs are typically limited to 1.5 stories or 24 feet in height. New rules allow more flexibility for 2-story units in specific contexts, but 1.5 is the still the standard for suburban-style neighborhoods.
Parking: Under state law HB24-1152, Denver generally cannot require you to build additional off-street parking for an ADU.
Owner Occupancy: This rule has been relaxed recently. You must live on the property at the time of the permit application, though some state-level updates are phasing out long-term enforcement of this.
What Specific Permits Do I Need?
Building an ADU is treated similarly to building a new primary residence. You will need three main types of approvals:
Zoning Permit: Confirms the structure meets the size, height, and placement (setback) rules for your specific lot.
Building Permit (Residential Construction Permit): A comprehensive permit covering the structural integrity, safety, and energy efficiency of the unit.
SUDP (Sewer Use and Drainage Permit): This is critical in Denver. It ensures your ADU’s waste and stormwater management are properly connected to city systems.
Trade Permits: Once the main building permit is issued, you (or your contractor) must pull:
- Electrical Permit
- Plumbing Permit
- Mechanical Permit (for HVAC/heating)
Landmark/Historic Review: If your home is in a designated Historic District (like Curtis Park or Whittier), you must get a certificate of appropriateness from the Landmark Preservation Commission first.
Step-by-Step Overview of the Denver Permitting Process?
Building an accessory dwelling unit in Denver is an exciting way to add value to your property and create space for the people you love. However, bringing your ADU dream to life means navigating Denver’s “E-permits” system. At Little Home Builder, we specialize in charting these complex terrains so you can build with confidence.
Denver uses a unique “Log” system, where your project is assigned a tracking number that moves through various city departments at the same time. Here is a look at what to expect during the permitting journey:
Phase 1: Pre-Submittal Preparation
Before we log in to the portal, we have to lay a solid administrative foundation.
- Assign an Address: Every ADU in Denver needs its own identity. We must request a unique address (like “Unit B”) from the city’s addressing team before your construction plans can be submitted.
- Landmark Review: If your home is nestled in one of Denver’s beautiful historic districts, we’ll need to obtain a Certificate of Appropriateness first. This Landmark Design Review ensures your new carriage house or cottage maintains the historic character of the neighborhood.
Phase 2: The Online Application (E-Permits)
Denver uses a centralized portal called E-permits. Rather than applying for zoning and building separately, we apply for a “Building Log” to keep everything organized.
- Simultaneous Review: To keep your project moving efficiently, Denver allows for a “simultaneous review.” This means we upload your Zoning, Building, and Sewer (SUDP) documents all at once.
- The SUDP Factor: The Sewer Use and Drainage Permit (SUDP) is often the piece with the longest lead time. It requires a detailed site plan showing exactly how your new unit connects to city sewer lines.
Phase 3: Plan Review & Revisions
Once submitted, your plans enter the “Review Loop.” We keep a close eye on the city’s real-time dashboard to track the progress of every discipline, from Structural to Zoning. If the city requests changes, we handle the resubmittals, using “delta clouds” to clearly highlight updates for the reviewers.
Phase 4: Permit Issuance & Trade Permits
The “Approved” stamp is the moment we’ve been waiting for! Once the master Residential Construction Permit is issued, we can move forward with the specialized work.
- Trade Permits: Only after the main permit is in hand can the Electrical, Plumbing, and Mechanical permits be “pulled.” These are generally issued instantly to our licensed contractors, ensuring the build stays on schedule.
Phase 5: Inspections & Occupancy
As we build your thoughtfully designed ADU, the city monitors progress through scheduled inspections.
- Final Building Inspection: This is the final step in the process. Once we pass the final inspection, the city issues a Certificate of Occupancy (CO). This is the legal green light that means your new space is ready to be inhabited!
Let Little Home Builders Manage Your ADU Permitting & Build
Little Home Builder is an experienced ADU builder serving Denver, Boulder, and other areas in Colorado. We have managed the permitting process for dozens of ADU projects. Get in touch today to learn more about starting your own ADU build.
