Adu services — St. Louis, MO | AccessoryDwellingUnit Services

Looking for adu services in St. Louis, MO? Call AccessoryDwellingUnit Services for a contact a provider — no obligation. Licensed adu builders serve St. Louis and the surrounding area, and you'll get straight answers on timing and what affects the price.

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

ADU services manage the technical side of building a backyard cottage or garage conversion. From verifying local property setbacks to plumbing and electrical connections, these professionals handle the logistics required to make a structure legal and habitable. You should reach out for these services when you have an idea for an extra living space but need a professional to ensure the project meets all safety codes and city regulations.

Frequently asked in St. Louis

What are the disadvantages of building an ADU in St. Louis?

How much does an ADU cost in Missouri?

The cost of an ADU in Missouri, including St. Louis, depends on many factors such as size, design, and materials used. Site preparation, foundation work, and utility connections also influence the final price. Simple backyard units are often less expensive. Getting a personalized quote is the best way to determine cost.

What are the rules for ADUs in St. Louis?

St. Louis has specific zoning ordinances and building codes that apply to ADUs, covering aspects like size, height, setbacks, and parking. It's crucial to be aware of these local regulations. We can help you understand these requirements.

Is an ADU allowed in my St. Louis neighborhood?

ADUs are permitted in many areas of St. Louis, but specific lot sizes, zoning, and neighborhood restrictions can apply. Verifying your property's zoning is a vital first step. We can help determine ADU feasibility for your specific location.

What is the permit process for ADUs in St. Louis?

The permit process involves submitting detailed construction plans to the City of St. Louis for review and approval, ensuring adherence to all building and zoning codes. This typically includes architectural and structural drawings. We can help you understand the necessary documentation.

Can I build a basement ADU in St. Louis?

Basement ADUs are often feasible in St. Louis, provided they meet egress requirements, ceiling height minimums, and other building code standards. You'll need to ensure your design complies with these regulations. We can discuss design options that work.

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

All cities in Missouri →

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