Everything homeowners ask about building an ADU in Denver — answered with 2026 data.
Yes, ADUs are allowed in All zones that allow a single-family dwelling (citywide as of CB24-1303, effective Dec 16, 2024) in Denver, CO. The maximum size for a detached ADU is Up to 1,000 sq ft on lots over 7,000 sq ft (864 sq ft on 6,000-7,000 sq ft lots; ~650 sq ft on smaller lots) — varies by zone district. Attached ADUs can be up to Up to 1,000 sq ft (varies by zone district). Denver has an ADU-friendliness score of 8/10. Check our full Denver ADU rules page for complete zoning details.
ADU construction in Denver typically costs $140,000-$280,000. The cost per square foot averages $130-$260. Garage conversions are more affordable at $70,000-$160,000, while prefab ADUs cost $100,000-$230,000. Permit fees add $500-$5,000 building permit + ~$2,055 Denver Water SDC (rising to $2,170 on Jul 1, 2026); total permit/utility typically $6K-$10K to your budget. See our detailed Denver ADU cost guide.
Detached ADUs in Denver can be up to Up to 1,000 sq ft on lots over 7,000 sq ft (864 sq ft on 6,000-7,000 sq ft lots; ~650 sq ft on smaller lots) — varies by zone district. Attached ADUs are limited to Up to 1,000 sq ft (varies by zone district). Junior ADUs (JADUs) have a cap of Confirm with Denver CPD (Denver regulates ADUs, not a separate JADU category). Maximum height is 24 ft / 1.5 stories maximum. You are allowed up to 1 ADU per single-family lot on a qualifying lot.
Rear setback: Must be within rear 35% of lot; 5 ft minimum rear setback. Side setback: Varies by lot width (typically 3-5 ft); confirm with Denver CPD. Front setback: Matches the primary structure front setback (varies by zone); a 15 ft separation is required between the house and the ADU. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
Not required (no parking minimum for ADUs per HB24-1152 / CB24-1303). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Not required (removed by CB24-1303, effective Dec 16, 2024; consistent with CO HB24-1152). Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Denver is typically 4-7 months realistic from application to issued permit (zoning + building review). Plan check: Several weeks to a few months depending on backlog. Pre-approved plans availability: Pre-approved/standard plan options available.
Average ADU rental income in Denver: 1-bedroom units rent for $1,400-$1,900/month, 2-bedroom units for $1,800-$2,500/month. Short-term rentals: Yes, with STR license. Expected ROI: 7-9% annual return.
The minimum lot size for an ADU in Denver is No minimum lot size (removed by CB24-1303). This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Denver, a garage conversion typically costs $70,000-$160,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.