Located at the base of Mount Diablo, Clayton offers small-town charm, scenic views, and generous lot sizes—making it an ideal location for building an Accessory Dwelling Unit (ADU). Whether you’re planning for aging parents, a rental unit, or a peaceful home office, an ADU gives you the freedom to grow without giving up the home and community you love.

At Royalty Builders, we provide complete ADU design and construction services customized for Clayton homeowners. From feasibility to final inspection, we take care of the entire process—ensuring your project is smooth, beautiful, and fully compliant with local building codes.

Types of ADUs We Build in Clayton

Clayton’s spacious properties and quiet neighborhoods are well-suited to a variety of ADU types. We tailor each project to meet your specific needs and optimize your property’s potential.

We specialize in:

• Detached ADUs – Ideal for private guest homes, long-term rentals, or multigenerational living

• Attached ADUs – Seamless expansions integrated into your existing home

• Garage Conversions – Turn underused garages into modern, livable spaces

• Above-Garage ADUs – A great way to add square footage vertically

• Basement ADUs – Smart use of existing lower-level space for private suites or offices

Every unit we build complies with Clayton’s zoning rules and Contra Costa County building requirements, ensuring safety, comfort, and long-term value.

Full-Service ADU Design + Build in Clayton

Royalty Builders takes a design-build approach, managing everything under one roof—from early planning to final construction. This saves time, reduces stress, and ensures top-tier results throughout the process.

Our full-service package includes:

• On-site property and zoning analysis

• Custom ADU design and 3D visualization

• Engineering, Title 24 energy compliance, and soil evaluations (if required)

• Complete permitting with the City of Clayton and Contra Costa County

• High-quality construction using trusted materials and local teams

• Final inspections, utility setup, and occupancy sign-off

We keep you informed every step of the way and ensure your ADU is built to last.

How Much Does It Cost to Build an ADU in Clayton?

ADU construction costs in Clayton vary based on design, terrain, and the type of unit. Whether you’re starting from scratch or converting existing space, we provide clear, itemized pricing to help you make informed decisions.

Typical ADU pricing in Clayton:

• Garage Conversion: $120,000 – $170,000

• Attached ADU: $180,000 – $290,000

• Detached ADU: $200,000 – $350,000+

• Above-Garage ADU: $220,000 – $360,000+

We also assist with financing options and partner with lenders who specialize in ADU and home improvement loans.

Permits for ADU Construction in Clayton – What You Need to Know

Although Clayton follows California’s ADU-friendly laws, it also maintains specific local regulations around lot setbacks, design standards, and hillside grading. Our experienced permitting team knows exactly how to navigate the process for a quick and compliant approval.

We take care of:

• Property assessments and lot eligibility

• Architectural plan submittals and engineering documentation

• Permit coordination with the City of Clayton and Contra Costa County

• Fire and safety code compliance (including hillside areas)

• Scheduling inspections and securing final approvals

We handle all the paperwork—so you can focus on your vision.

Why Build an ADU in Clayton?

Clayton offers peaceful living, strong community ties, and some of the East Bay’s most desirable views—all within commuting distance to Concord and Walnut Creek. Building an ADU in Clayton helps you take full advantage of your property while planning for the future.

Top reasons Clayton homeowners are building ADUs:

• 🏠 Additional space for family members or guests

• 💼 Home office or studio space for remote work or hobbies

• 💰 Passive income from long-term tenants

• 📈 Increased resale value and market appeal

• 🔁 Multigenerational living or aging-in-place solutions

An ADU provides comfort, flexibility, and long-term return—all within your own backyard.

Frequently Asked Questions – ADUs in Clayton

Q: Can I build an ADU on my lot in Clayton?
A: Most residential properties in Clayton are eligible for an ADU. We’ll confirm your zoning and setbacks during your consultation.

Q: What’s the maximum size for an ADU in Clayton?
A: Typically up to 1,200 sq. ft. for a detached unit, depending on your lot and coverage. We’ll verify what’s allowed based on your property details.

Q: Are parking spaces required?
A: Not always. Parking may be waived under certain conditions like proximity to transit or conversion of an existing structure. We’ll check for you.

Q: How long does it take to build an ADU?
A: Most ADUs take 6–10 months from start to finish. We provide a clear project timeline and manage the process from day one.

Contact Royalty Builders – Clayton’s Local ADU Contractor

Looking to expand your Clayton home with a fully permitted, beautifully built ADU? Royalty Builders is here to guide you through the process and deliver exceptional results.

📞 Contact us today and schedule your free ADU consultation in Clayton.

Smart design. Lasting value. Built with Royalty.