TRUSTED ADU CONSTRUCTION
ADU Builders
From backyard studios to full two-story dwellings, 9Builders delivers expertly crafted Accessory Dwelling Units across the Bay Area.
Get a Free QuoteQuality ADUs That Fit Your Budget
At 9Builders, we combine efficient project management, innovative design, and high-grade materials to bring your ADU vision to life — whether it's rental income, a guest suite, or a private office.
Cost-Effective Solutions
By using smart, sustainable materials and techniques, we minimize costs without compromising on quality.
Transparency and Communication
We keep you informed at every step, ensuring there are no hidden surprises along the way.
Customizable Designs
From modern to traditional styles, we tailor each ADU to complement your property and lifestyle.
Expert Craftsmanship
Our skilled builders take pride in creating ADUs that are built to last, with meticulous attention to every detail.
What is ADU?
An ADU (Accessory Dwelling Unit) is a small, secondary housing unit built on the same property as a single-family home. They are often designed to provide extra living space, generate rental income, or create a private area for family members. ADUs come in various forms, such as:
ADUs typically include basic amenities like a bedroom, bathroom, kitchen, and living area, making them self-contained homes. They're popular in areas with high housing costs as they provide affordable living solutions without requiring new land development.
Detached ADU
A separate building, often located in the backyard.
Attached ADU
An addition to the main house with its own entrance.
Garage Conversion
Converting an existing garage into a living unit.
Basement or Attic Conversion
Transforming a basement or attic into an independent unit.
Innovative ADU Design Solutions
Our approach to ADU design focuses on maximizing functionality, style, and efficiency, transforming small spaces into versatile, livable homes.
Smart Space Planning
Each square foot is carefully planned to create a comfortable and practical layout. We specialize in open floor plans that integrate living, dining, and kitchen areas.
Modern & Versatile Aesthetics
Our ADU designs are tailored to match or complement the main residence, whether you prefer modern, rustic, or minimalist styles.
Energy-Efficient Solutions
Our ADUs incorporate eco-friendly features like energy-efficient windows, solar panel options, LED lighting, and quality insulation.
Customized Amenities
From luxury touches like granite countertops to practical features like built-in storage, every detail is designed with purpose.
Outdoor Integration
Where possible, our ADU designs feature patios, decks, or gardens, extending the living space to the outdoors.
What We Offer
Full-service ADU construction tailored to your lot, your budget, and your timeline.
Custom Design
We work with you to create a layout that fits your property and lifestyle — from studio plans to multi-bedroom homes.
Permits & Approvals
We navigate San Jose and Bay Area permitting so you don't have to. Our team handles every submission and revision.
Quality Construction
Licensed, insured, and committed to building code compliance, energy efficiency, and lasting craftsmanship.
Why Choose 9Builders
We combine local expertise, transparent pricing, and hands-on project management to deliver ADUs that exceed expectations.
End-to-End Service
Design, permits, construction, and inspection — all under one roof.
Bay Area Specialists
Deep knowledge of local zoning, setback rules, and building codes across Santa Clara County.
Transparent Pricing
Detailed estimates up front with no hidden fees or surprise change orders.
On-Time Delivery
We set realistic timelines and stick to them, keeping you informed at every stage.
Built for the Bay Area
Every neighborhood has its own character, zoning rules, and design expectations. That's why we tailor each ADU project to the specific requirements of your city — from lot setbacks in San Jose to architectural standards in Los Gatos. Wherever you are in the Bay Area, 9Builders brings the local knowledge to get it done right.
Areas We Serve
We serve homeowners across the Bay Area. Click your city to learn more.
ADU Builders Alamo
Upscale properties and spacious lots make Alamo ideal for premium ADU construction and guest house builds.
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ADU Builders Bay Area
Region-wide coverage across 15+ cities with deep knowledge of each municipality's unique ADU regulations.
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ADU Builders Belmont
Hillside expertise and custom engineering for Belmont's sloped lots and scenic residential neighborhoods.
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ADU Builders Campbell
Space-smart ADU designs for Campbell's walkable neighborhoods and charming downtown community.
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ADU Builders Cupertino
Tech-forward ADUs with smart home features, energy efficiency, and modern aesthetics for Cupertino homeowners.
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ADU Builders Fremont
Versatile ADU solutions across Fremont's diverse neighborhoods, from Niles to Mission San Jose.
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ADU Builders Los Altos
Luxury craftsmanship and premium finishes that match Los Altos' distinguished residential character.
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ADU Builders Los Gatos
Elegant ADU designs that honor Los Gatos' historic charm, hillside terrain, and architectural heritage.
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ADU Builders Milpitas
Affordable, high-quality ADUs positioned to capture strong rental demand near tech employers and BART.
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ADU Builders Mountain View
Modern, sustainable ADU construction for Mountain View's innovation-driven community and strong rental market.
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ADU Builders Palo Alto
Design-review-ready ADUs built to Palo Alto's exacting standards with premium materials and green building practices.
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ADU Builders San Jose
The Bay Area's largest ADU market — hundreds of projects completed across San Jose's diverse neighborhoods.
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ADU Builders Santa Clara
Central Silicon Valley location means strong rental demand and excellent returns on your ADU investment.
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ADU Builders Saratoga
Estate-quality ADU construction with landscape preservation and luxury finishes for Saratoga's prestigious properties.
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ADU Builders Sunnyvale
Efficient, modern ADUs designed to attract tech professionals and maximize rental income in Sunnyvale's hot market.
Read More →ADU Construction FAQs: What You Need to Know
Some videos showcasing our recent work.
What Our Customers Say
Our clients are at the heart of everything we do at 9Builders, and their feedback reflects our dedication to quality and service. From beautiful remodels to innovative new builds, hear how we've transformed their spaces and exceeded their expectations.
Tommy, Yuna, and their entire team were amazing from start to finish. We hired them for a big project that included foundation work, a structural retrofit, replacing the PGE main service line, and installing a new 200-amp panel. It was a pretty major job, and honestly, we couldn't have asked for a better crew to handle it. Everyone was professional, polite, and knew exactly what they were doing. They showed up on time, cleaned up every day, and were super respectful of our space.
I hired 9Builders to work on my backyard and they did an amazing job. They built a nice structure that looks really great and added so much to my yard. The team was friendly and kept everything clean while they worked. The work was done quick and looked really good. Now they're working on the front of my house to add an extension, and I'm impressed how fast they worked. They finished the foundation in just two days...
9Builders transformed our kitchen into a beautiful, functional space. They listened to our ideas, offered great suggestions, and delivered high-quality work. The team was professional and respectful throughout.