Cost to build accessory dwelling unit — Denver, CO

Last updated: September 24, 2026

In Denver, the approach to adding an Accessory Dwelling Unit (ADU) can differ significantly between older, established homes and newer constructions. If you're looking to maximize your property's potential, whether in a historic Denver neighborhood or a recently developed area, an ADU is a fantastic option. Perhaps you've noticed more carriage houses or backyard cottages popping up and wondered if it's a viable path for you. You're likely concerned about the upfront costs, the permitting process, and finding trustworthy builders who understand Denver's unique building environment. It's natural to have questions about regulations and how an ADU will integrate with your existing home. We're here to provide clear, direct answers and guide you through each step. Our aim is to make adding an ADU a smooth and rewarding experience for Denver homeowners. When you're ready to explore the possibilities, a simple call can set you on the right track.

What affects the price

Building an ADU involves several moving parts that shape your total investment. The final figure depends heavily on whether you choose a prefab unit or a custom build from the ground up. Site conditions are another major factor; if your property requires extensive grading, utility trenching, or foundation work, costs will climb. You also have to consider your choice of finishes, like high-end appliances or custom cabinetry. Navigating local permit fees and impact assessments also adds to the total.

About this service

When estimating the cost to build, consider the difference between a prefab unit and custom construction, as well as site preparation requirements like clearing trees or grading land. Labor and material prices also play a significant role. We provide an exact pricing confirmed free on the call.

Frequently asked in Denver

Also serving nearby: Aurora · Thornton · Centennial · Westminster · Lakewood

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More on this: HUD ADU resources — ADU policy and financing research.

Service area details

Serving all of Denver — population 716,577; about 4,681 residents per square mile across 153.1 sq mi. ZIP codes covered include 80201, 80202, 80203, 80204, 80205, 80206, 80207, 80208.

Neighborhoods served in Denver: LoDo (Lower Downtown), Capitol Hill, Cherry Creek, RiNo (River North Art District), Washington Park, Highlands — and every surrounding area.