Best accessory dwelling unit — St. Louis, MO

Last updated: September 24, 2026

What affects the price

Building an ADU is a custom project, so costs vary based on your specific choices. Site conditions are the biggest factor; if your land requires significant grading, utility extensions, or foundation work, those expenses add up quickly. Choosing high-end finishes, custom cabinetry, or complex roof lines will also push the budget higher compared to a standard design. Prefabricated units often offer predictable costs, while custom site-built structures allow for more flexibility but can be harder to estimate upfront. Exact pricing confirmed free on the call.

About this service

The best ADU for your property is one that increases your home value while meeting your specific lifestyle needs. Whether you need a private office, a rental income source, or a space for family, the right unit features durable materials and an efficient layout. We focus on high-quality construction that stands the test of time, ensuring your investment is built to last. We help you design the perfect fit. Exact pricing confirmed free on the call.

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: Tower Grove, Soulard, Central West End, The Hill, Benton Park — and every surrounding area.