Is an ADU worth building in Denver?

For most Denver metro homeowners, yes. A $200,000 detached ADU generating $2,000/month in rent breaks even in roughly 8 years on rental income alone — not counting the $100,000–$250,000 increase in assessed property value that ADUs typically add.

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How Much Does an ADU Cost in Denver?

Q: What is the cheapest ADU to build in Denver?

Garage conversions are typically the most affordable ADU option in Denver, ranging from $80,000–$130,000. Because the structure already exists, you save on foundation, framing, and roofing costs. Basement conversions are the next most affordable at $100,000–$180,000.

A realistic breakdown of ADU construction costs across the Denver metro — by type, size, and what drives the price up or down.

COST BREAKDOWN BY ADU TYPE

Garage Conversion

$80,000 – $130,000

• Existing structure reduces costs
• Electrical and plumbing additions
• Insulation, drywall, finishes
• Separate entrance and egress
• Best for: properties with alley-accessed garages

Basement ADU

$100,000 – $180,000

• Separate entrance installation
• Egress windows required
• Full kitchen and bathroom
• HVAC modifications
• Best for: homes with full unfinished basements

Detached Backyard ADU

$180,000 – $350,000

• New foundation and structure
• Full utility connections
• Maximum privacy and rental value
• Typically 400–1,200 sq ft
• Best for: larger lots with yard space

WHAT DRIVES ADU COSTS UP OR DOWN

Cost Factors That Increase Price

Lot slope or difficult access: Sloped lots require grading, retaining walls, or specialized foundations that add $10,000–$40,000.
Distance to utility connections: If sewer, water, or electrical lines are far from the ADU site, trenching and connection costs increase significantly.
Premium finishes: Upgrading from builder-grade to premium cabinets, countertops, fixtures, and flooring can add $20,000–$60,000.
Larger square footage: A 1,200 sq ft detached ADU costs significantly more than a 500 sq ft unit.
Complex permitting: Some cities or neighborhoods require design review, variance requests, or additional documentation.

Factors That Reduce Cost

Existing structure (garage/basement): Converting saves on foundation, framing, and roofing — often 30–50% less than new construction.
Alley access: Properties with alley access avoid the cost of building a new driveway or access path.
Flat lot with close utilities: Short utility runs and level ground minimize site preparation costs.
Standard finishes: Builder-grade materials that still look good keep costs controlled without sacrificing quality.
Efficient design: Compact, well-designed layouts maximize livable space without unnecessary square footage.

COST VS. ROI: IS AN ADU WORTH IT?

For most Denver metro homeowners, the answer is yes. Here's a simplified example:

CONSTRUCTION COST

$200,000

Detached backyard ADU

ANNUAL RENTAL INCOME

$24,000

$2,000/month average

BREAK-EVEN

~8.3 Years

Plus property value increase

Most Denver ADUs also increase assessed property value by $100,000–$250,000 — meaning your net investment starts positive much sooner than the rental break-even suggests. Denver's housing shortage means ADU rental vacancy rates are extremely low.

ADU COST FAQS

Garage conversions are typically the most affordable option, ranging from $80,000–$130,000. Because the structure already exists, you save on foundation, framing, and roofing costs. Basement conversions are the next most affordable at $100,000–$180,000.

The biggest cost drivers are: ADU type (detached vs. conversion), size (400 sq ft vs. 1,200 sq ft), lot conditions (slope, access, utility distance), finish level (builder-grade vs. premium), and local permit fees. Every property is different — that's why we start with a free site assessment.

We don't offer direct financing, but we work with homeowners who use home equity loans, HELOCs, construction loans, and cash-out refinances to fund their ADU projects. We can provide the detailed estimates your lender will need.

Well-finished ADUs in the Denver metro typically rent for $1,500–$2,500/month depending on size, location, and finishes. Studios and one-bedrooms on the lower end, two-bedrooms and premium finishes on the higher end.

Get an Honest ADU Estimate

Every property is different. We'll assess your lot, discuss your goals, and give you a realistic cost range — free, no obligation.

(303) 915-3575 REQUEST FREE ESTIMATE