Accessory dwelling unit companies

Looking for accessory dwelling unit companies in St. Louis, MO? Call AccessoryDwellingUnit Experts 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 is a major project, and the final bill depends on a few key things. Site prep is a big factor; if your land is sloped or needs extensive utility connections, costs go up. The materials you choose—from siding to kitchen finishes—also change the math significantly. Whether you’re building a detached unit or converting an existing garage shifts the permit requirements and structural work needed. We provide exact pricing confirmed free on the call.

About this service

These companies provide end-to-end management for property owners looking to add a secondary unit. They typically offer a mix of design, permitting, and construction management services to streamline the project. You need to hire a company when you want a structured, professional approach to the entire build process rather than managing individual subcontractors yourself. They help ensure your unit is built to code, on time, and aligned with your budget goals.

Frequently asked in St. Louis

What are the disadvantages of ADUs in St. Louis?

In St. Louis, potential disadvantages could include navigating the city's historic district regulations if your property is within one, which can add complexity. You'll also want to consider the impact on your property taxes and insurance. A local pro can help you anticipate these factors.

How much does an ADU cost in Missouri?

What are the rules for ADUs in Missouri?

Missouri has state-level ADU considerations, but St. Louis has its own specific zoning ordinances that homeowners must adhere to. These rules often pertain to lot size, setbacks, and the relationship between the ADU and the primary residence. Getting local guidance is essential for compliance.

Is an ADU allowed in St. Louis?

Yes, ADUs are permitted in St. Louis, but they must meet the city's zoning code requirements. These regulations commonly address aspects like lot coverage, parking, and the overall design to ensure compatibility with existing neighborhoods. A call to us can clarify the rules for your specific situation.

What is the grant for ADUs in California?

Missouri, and specifically St. Louis, does not have a similar state-funded grant. However, there may be local financing options or programs available that we can help you explore.

What are the rules for ADU in California?

California has enacted robust legislation to promote ADU construction, often with statewide standards. These laws aim to increase housing availability. If you're in St. Louis, Missouri, your focus should be on the specific ordinances set by the city and the state of Missouri.

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

All cities in Missouri →

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