Accessory dwelling unit services — St. Louis, MO

Last updated: September 24, 2026

What affects the price

Building an ADU involves several moving parts that shape your total budget. The biggest factor is whether you choose a prefabricated unit or a custom build on-site. Site preparation is also significant; if your land requires extensive grading, utility trenching, or foundation work, costs will climb. Your choice of finishes—like kitchen cabinetry, flooring, and siding materials—also shifts the bottom line. We help you navigate these variables to find a setup that fits your property. Exact pricing confirmed free on the call.

About this service

These services cover the entire lifecycle of a backyard home, from initial property assessments to navigating local permit applications. You need this when you want to add living space but don't want to handle the complex zoning paperwork or design requirements yourself. Professionals guide you through the rules to ensure your project stays compliant with state and city codes while maximizing your property’s potential for rental income or housing family members.

Frequently asked in St. Louis

Also serving nearby: O Fallon · Springfield · Columbia · Champaign · Peoria

All cities in Missouri →

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

Service area details

Serving all of St. Louis — population 281,754; about 4,565 residents per square mile across 61.7 sq mi.

Neighborhoods served in St. Louis: The Hill, Central West End, Tower Grove South, Soulard, CWE — and every surrounding area.