Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Denver ADU cost →Building an ADU in Denver costs between $140,000-$280,000 for new construction, with per-square-foot costs averaging $130-$260. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $70,000-$160,000, while prefab/modular ADUs fall in between at $100,000-$230,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | $500-$5,000 building permit + ~$2,055 Denver Water SDC (rising to $2,170 on Jul 1, 2026); total permit/utility typically $6K-$10K |
| Impact Fees | Denver Water system development charge applies; see fees |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. Get up to 3 free quotes from ADU builders serving Denver — no obligation.
Get Denver builder quotes →Permit fees in Denver are $500-$5,000 building permit + ~$2,055 Denver Water SDC (rising to $2,170 on Jul 1, 2026); total permit/utility typically $6K-$10K. The review timeline is 4-7 months realistic from application to issued permit (zoning + building review), with plan check: Several weeks to a few months depending on backlog. Impact fees are Denver Water system development charge applies; see fees. Pre-approved plans: Pre-approved/standard plan options available.
| 1-Bedroom Rent | $1,400-$1,900/month |
| 2-Bedroom Rent | $1,800-$2,500/month |
| Annual Rental Income (est.) | $19,800/year |
| Payback Period (est.) | 10.6 years |
| Short-Term Rental | Yes, with STR license |
| Overall ROI Estimate | 7-9% annual return |
A typical ADU in Denver generates approximately $19,800 per year in rental income based on average 1-bedroom rents. At an average construction cost of $210,000, the estimated payback period is 10.6 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Denver and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Denver: $70,000-$160,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $100,000-$230,000.
3. Pre-approved plans — available in Denver, which can save $3,000-$10,000 in design costs and 2-3 months in review time.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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