What's Required in Denver
- ADUs are allowed citywide in all residential zones as of 2026 (Group Living amendment).
- Maximum size based on lot size: 650 sq ft (lot <6k) to 1,000 sq ft (lot >7k).
- Must have independent kitchen, bathroom, and a separate entrance.
- Owner-occupancy requirement for the primary residence has been removed.
- Must maintain setbacks appropriate for the specific zone district.
- No additional off-street parking is required for ADU units in Denver.
How Much Does an ADU Permit Cost in Denver?
Budget $2,000–$6,000 for the Denver permit itself (valuation-based), issued by the Denver Community Planning and Development — but treat that as the entry fee, not the total. ADUs are full dwelling units, so the permit stack usually includes building, electrical, plumbing, and mechanical trade permits, plus plan review. One local note: covers plan review, building permit, SUDP, and Denver Water system development charges. Get an itemized fee estimate from the department before finalizing your budget; the spread between a simple conversion and a new detached build is wide.
ADU Size Limits and Zoning Rules in Denver
Before drawing plans, check the two gates that sink most ADU projects: size and zoning. Size ceilings vary by lot and ADU type (attached, detached, or conversion), so confirm your specific configuration. Other recorded conditions: owner-occupancy requirement for the primary residence has been removed; no additional off-street parking is required for ADU units in Denver. Setbacks, height limits, and utility connections layer on top of those rules. The Denver Community Planning and Development can confirm what your specific lot allows — worth doing before you pay for architectural drawings rather than after.
How to Get a ADU Permit in Denver
Step 1: Check Size Limits
Identify your maximum ADU size based on your property's lot square footage (2026 rules).
Step 2: SUDP Submission
Apply for a Sewer Use and Drainage Permit to ensure wastewater capacity.
Step 3: Portal Submission
Submit 'Residential New Construction' application via Denver E-Permits.
Step 4: Fee Payment
Pay the permit, plan review, and Denver Water impact fees ($2,000+ typical).
Step 5: Full Inspection Series
Schedule Foundation, Framing, Rough MEP, and Final inspections.