Accessory dwelling unit permit cost — Naperville, 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.
Frequently asked in Naperville
What makes a good local ADU company in Naperville?
How much does an Accessory Dwelling Unit typically cost in Naperville?
What does 'Accessory Dwelling Unit' actually mean for a Naperville homeowner?
What should I look for in an ADU unit for my Naperville property?
How do I get a free ADU estimate in Naperville?
Are there affordable Accessory Dwelling Unit options for Naperville residents?
What kind of Accessory Dwelling Unit services are available in Naperville?
Also serving nearby: Aurora · Joliet · Elgin · Chicago · Waukegan
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Naperville — population 150,245; about 3,836 residents per square mile across 39.2 sq mi. ZIP codes covered include 60540, 60563, 60564, 60565, 60566, 60567.
Neighborhoods served in Naperville: Downtown Naperville, East Highlands, Huntington Estates, Naperville Country Club, Riverwalk — and every surrounding area.
Areas we serve
Browse by state, then city.