Cost to build accessory dwelling unit — Chicago, IL

Last updated: September 24, 2026

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 Chicago

Also serving nearby: Naperville · Aurora · Joliet · Elgin · Waukegan

All cities in Illinois →

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

Service area details

Serving all of Chicago — population 2,664,452; about 11,699 residents per square mile across 227.7 sq mi. ZIP codes covered include 60601, 60602, 60603, 60604, 60605, 60606, 60607, 60608.

Neighborhoods served in Chicago: Lincoln Park, Wicker Park, Hyde Park, Rogers Park, Pilsen — and every surrounding area.