Denver County · Updated 2026
Denver ADU Cost Guide: $180K–$450K in 2026
Colorado's 2024 statewide ADU law opens all residential zones — here's what it means for your Denver project.
Last updated: •Reviewed by the aduglossary editorial team
Quick Answer
Denver ADUs: $180K–$450K
Permits: $7K–$30K · Updated April 2026
ADU Costs in Denver: Overview
Denver is one of the fastest-growing cities in the Mountain West, and ADUs have become a critical piece of the city's housing strategy. Colorado's landmark 2024 statewide ADU law (HB24-1152) now requires all residential zones across the state to allow ADUs, removing the patchwork of neighborhood-by-neighborhood restrictions that previously complicated projects. For Denver homeowners, this means greater certainty when planning an ADU — and a faster path from concept to permit submission.
Total project costs in Denver run $180,000–$450,000, with per-square-foot construction costs of $400–$550. Denver's high altitude and climate add unique cost factors not seen in coastal cities: heavier insulation requirements, engineered snow load roofing, and frost-depth foundations all add to the build cost but are essential for Colorado's weather. Permit fees total $7,000–$30,000+ depending on ADU size and type.
Cost by ADU Type
| ADU Type | Cost Range | Best For |
|---|---|---|
| Detached ADU | $250K–$450K | Maximum privacy, highest rental income |
| Attached ADU | $200K–$350K | Shared wall, lower cost than detached |
| Garage Conversion | $140K–$280K | Uses existing structure, most cost-effective |
| Basement Conversion | $80K–$180K | Lowest cost, existing footprint and foundation |
Per square foot costs in Denver: $400–$550. Garage conversions: $200–$300/sq ft. Updated 2025.
What Drives ADU Costs in Denver?
Denver's ADU cost profile is shaped by three factors not present in most other markets:
Colorado 2024 Law Changes
HB24-1152 eliminated owner-occupancy requirements statewide and mandated that all residential zones allow ADUs. For Denver homeowners, this reduces legal uncertainty and eliminates the need for variance applications in previously restricted zones. The law has also spurred the city to streamline its e-permits review process.
Altitude, Weather, and Construction Requirements
Denver's 5,280-foot elevation and temperature swings (-10°F to 100°F) drive mandatory engineering upgrades. ADUs require thicker insulation (R-49+ roof, R-21+ walls), frost-depth foundations (36–42 inches), and roofing engineered for 40–60 lb/sq ft snow loads. These add $15,000–$40,000 versus a comparable build in a moderate-climate city.
Utility Tap Fees and SUDP Costs
Denver requires a Sewer Use and Drainage Permit (SUDP) for both the main house and the new ADU — $632 each, so $1,264 minimum just for SUDP. New utility connections (water, sewer, electric) for a detached ADU add $10,000–$25,000 depending on distance from existing service. Attached ADUs and conversions sharing utilities are significantly cheaper to connect.
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Get Your EstimateNeighborhood Cost Breakdown
Capitol Hill
Dense urban neighborhood with strong rental demand from young professionals and healthcare workers near the medical campus. Smaller lots favor attached ADUs and basement conversions ($80K–$200K). Historic district designation in parts of the neighborhood adds design review time. Rental income: $1,600–$2,400/month.
Park Hill
Established east Denver neighborhood with larger lots that support detached ADU construction. Bungalow-era homes often have detached garages ripe for conversion ($140K–$220K). Strong family rental demand. Detached ADUs: $260K–$400K. Rental income: $1,700–$2,500/month.
Highlands
One of Denver's most desirable neighborhoods, with high property values and premium rental rates. Detached ADUs command top-of-market construction costs ($300K–$450K) but generate rental income of $2,000–$2,800/month. Proximity to downtown drives consistent demand.
Stapleton / Central Park
Planned community with newer housing stock and larger lot sizes. HOA restrictions may limit ADU design (per CO 2024 law, HOAs cannot outright prohibit ADUs but may impose reasonable design standards). Good family rental demand near Stanley Marketplace. Detached ADUs: $250K–$380K.
Lakewood
Jefferson County suburb adjacent to Denver with its own zoning code, but subject to the same CO 2024 state ADU law. Larger suburban lots, more affordable construction costs, and strong demand from light rail commuters. Garage conversions popular at $120K–$200K. Rental income: $1,500–$2,200/month.
Frequently Asked Questions
How much does an ADU cost in Denver?
ADU costs in Denver range from $180,000 to $450,000 depending on type and size. Detached ADUs run $250,000–$450,000, attached ADUs $200,000–$350,000, garage conversions $140,000–$280,000, and basement conversions $80,000–$180,000. Per square foot construction costs are $400–$550, higher than many markets due to Colorado's altitude, climate engineering requirements, and local labor rates.
Do I need permits to build an ADU in Denver?
Yes. Denver requires three permits: a zoning review permit, a building permit, and a Sewer Use and Drainage Permit (SUDP). All permits are submitted through Denver's e-permits online system. Simultaneous review of zoning and building permits is available and can reduce total review time. Total permit fees run $7,000–$30,000+.
What did Colorado's 2024 ADU law change?
Colorado's HB24-1152 (effective 2024) requires all municipalities to allow ADUs in residential zones. In Denver, this eliminated many neighborhood-level restrictions and removed the owner-occupancy requirement — you are not required to live on the property to rent an ADU. HOAs may impose reasonable design standards but cannot prohibit ADUs outright. This law significantly expanded where and how Denver homeowners can build ADUs.
How long does it take to build an ADU in Denver?
A typical Denver ADU project takes 10–18 months from start to certificate of occupancy. Design and engineering takes 1–3 months, city permit review 3–6 months (historic districts take longer), and construction 6–12 months depending on ADU type. Basement conversions are generally faster to build than detached new construction. Using Denver's simultaneous review process can trim several weeks from the permitting phase.
What rental income can I expect from a Denver ADU?
Denver ADU rental income typically ranges from $1,500 to $2,800 per month. Studios and 1-bedroom ADUs in Capitol Hill or Highlands rent for $1,800–$2,500/month. Larger 2-bedroom detached ADUs in desirable neighborhoods command $2,200–$2,800/month. Denver's ongoing housing shortage — the city has a vacancy rate well below the national average — drives consistent tenant demand for well-built ADUs.
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