ADU Contractors in St. Louis, MO: What You Need to Know

Accessory Dwelling Units (ADUs) are becoming increasingly popular across the country, and St. Louis is no exception. Whether you’re considering an ADU for extra income, a private space for family, or simply to increase property value, the right contractor makes all the difference. In this guide, we’ll cover everything homeowners need to know about ADU contractors in St. Louis, MO, from zoning rules to construction tips, so you can confidently move forward with your project.

1. What is an ADU?

An Accessory Dwelling Unit (ADU) is a secondary living space built on the same lot as a primary home. ADUs may be detached (like a backyard cottage or garage conversion), attached (an extension to your home), or internal (like a basement or attic apartment). They’re designed to be fully functional residences with their own kitchen, bathroom, and living space.

2. Why Build an ADU in St. Louis?

Rental income potential – Short-term or long-term rentals can help offset mortgage costs.
Multi-generational living – Perfect for aging parents, adult children, or extended family members.
Increased property value – A well-designed ADU adds value and versatility to your home.
Flexibility – Use it as a home office, studio, or guest house.

With the rise of remote work and affordable housing challenges, ADUs are a smart solution for many St. Louis homeowners.

3. St. Louis Zoning and Permits for ADUs

Before breaking ground, you’ll need to understand local zoning laws and building codes. St. Louis has specific requirements regarding:

Minimum lot sizes
Setback distances from property lines
Height restrictions
Parking requirements
Utility hookups and separate meters

Working with an experienced ADU contractor in St. Louis, MO ensures your project complies with all local regulations. They can also handle permit applications and inspections on your behalf.

4. Choosing the Right ADU Contractor in St. Louis

Finding the right contractor is the most important decision you’ll make. Here’s what to look for:

Experience with ADUs – Not every remodeling contractor has expertise in building fully functional, code-compliant ADUs.
Portfolio of local projects – Ask for examples of completed ADUs in St. Louis.
Licensing and insurance – Verify credentials to protect your investment.
Transparent estimates – A detailed breakdown of costs avoids surprises later.
Clear communication – Choose someone who explains the process, timeline, and potential challenges upfront.

5. Costs of Building an ADU in St. Louis

The cost of an ADU can vary widely depending on size, design, and finishes. On average:

Garage conversions: $60,000–$100,000
Detached ADUs: $100,000–$250,000+
Basement or attic conversions: $50,000–$120,000

Your contractor should help you balance budget and quality while suggesting cost-saving strategies that don’t compromise safety or compliance.

6. Design Considerations

ADUs should be both functional and appealing. When designing, consider:

Natural lighting and ventilation
Maximizing limited square footage with smart layouts
Matching or complementing your main home’s style
Accessibility features if used for aging family members

A skilled St. Louis ADU contractor can guide you in creating a space that’s practical and beautiful.

FAQ: ADU Contractors in St. Louis, MO

Q: Are ADUs legal in St. Louis?
Yes, but they are subject to zoning and building code restrictions. Working with a local contractor ensures compliance.

Q: How long does it take to build an ADU?
Typically, 4–9 months, depending on permits, complexity, and whether it’s a conversion or new construction.

Q: Do I need separate utilities for my ADU?
In most cases, yes. Contractors will handle plumbing, electrical, and HVAC connections to meet code requirements.

Q: Will an ADU increase my property taxes?
Yes, since it increases property value. However, many homeowners find rental income offsets this cost.

Q: Can I finance an ADU build?
Yes. Options include home equity loans, cash-out refinancing, or renovation loans. Some lenders now offer ADU-specific financing.

Building an ADU is a major investment, but with the right guidance, it can transform your property into a more functional, valuable, and flexible space. From navigating zoning laws to designing and constructing a beautiful living unit, the contractor you choose matters.

At CTM Construction, we specialize in building ADUs in St. Louis, MO with a focus on quality, compliance, and communication. Whether you’re dreaming of a rental unit, in-law suite, or backyard cottage, our experienced team is here to bring your vision to life.

👉 Contact CTM Construction today to schedule your consultation and discover how we can help you create the perfect ADU.