How Much Does It Cost to Build an ADU in Denver in 2026?

As we’ve been talking to homeowners, neighborhood groups and city officials across the metro area, one of the most searched questions is: What does a Denver ADU cost? In 2026, most detached ADUs in Denver fall within a broad range. Garage conversions and basement ADUs may cost less, while custom carriage houses with full kitchens, premium finishes, and alley-loaded access typically sit at the higher end. 

 Most detached ADUs in Denver fall within a broad range depending on:

• Square footage
• Site conditions and alley access
• Utility connections and sewer upgrades
• Architectural design complexity
• Interior finish selections
• Structural engineering requirements

What’s important for you to remember is that the true cost isn’t just construction — it includes architectural plans, permitting fees, structural engineering, utility work, and impact fees. Here are a few ranges to help you understand the costs to build an ADU in Denver

• Average design cost 
• Land Use Permit 
• Sewer and Utility fees 
• Insulation and requirements for energy code: 
• Removal of existing structure 
• Foundation 

We often say that you should feel comfortable spending $350,000 on an ADU. We may well be able to build it for less, but with the amount of cost that goes to things that aren’t just the construction, we want you to feel comfortable. And for us, that is what matters most. Cost certainty

Where many homeowners get frustrated is with unpredictable pricing. Vague allowances, change orders, and unclear scopes can cause budgets to balloon mid-project. And because so many companies offering to build ADUs are either new or treat ADUs as an add-on other services, they don’t understand the full scope of services. We operate differently. v

That’s our No Surprises Guarantee.