Portola Valley is known for its scenic beauty, spacious lots, and a strong commitment to preserving its natural surroundings. For homeowners looking to expand their property in a thoughtful, elegant way, building an Accessory Dwelling Unit (ADU) is the perfect solution. At Royalty Builders, we specialize in designing and building high-end ADUs in Portola Valley that enhance your lifestyle while respecting the character of your property.

Whether you’re envisioning a detached guest house, an in-law suite, or a luxury office retreat nestled in nature, we provide full-service design + build solutions from start to finish.

Why Build an ADU in Portola Valley?

Portola Valley offers a rare blend of privacy, tranquility, and connection to the outdoors—qualities that make ADUs especially valuable. With large parcels of land and minimal density, many properties are well-suited for standalone or semi-attached units that maintain privacy and aesthetic harmony.

Building an ADU in Portola Valley allows you to:

• Create a comfortable living space for aging parents or adult children

• Welcome guests with a private retreat

• Build a serene home office, studio, or fitness space

• Add long-term value to your estate

• Future-proof your property for changing family needs

• Preserve your lifestyle while expanding functionality

With new state laws requiring towns to accommodate ADU development, it’s easier than ever to create a flexible, high-end living space on your land—without compromising on design or privacy.

Full-Service ADU Design + Build in Portola Valley

At Royalty Builders, we specialize in custom ADU projects that reflect the natural beauty and architectural standards of Portola Valley. We take a holistic approach, managing the entire process under one roof—from vision to permits to construction—so you can enjoy a seamless experience and a stunning result.

Our comprehensive process includes:

• Site Assessment & Feasibility: We evaluate your lot’s terrain, views, and access to determine the best type and location for your ADU.

• Architectural Design & Planning: Our in-house designers create a beautiful, sustainable, and highly functional design tailored to your home and landscape.

• Permitting & Coordination: We manage all documentation, communication, and approvals with the Town of Portola Valley.

• Premium Construction: Our skilled crews build your ADU to the highest standards using quality materials, modern techniques, and environmental sensitivity.

• Final Walkthrough & Long-Term Support: We ensure your satisfaction with the completed project and remain available for any future support you may need.

Our team understands the unique zoning, building codes, and design review process in Portola Valley and will guide your project every step of the way.

Types of ADUs We Build in Portola Valley

Depending on your goals and property layout, we offer several types of ADUs:

• Detached ADUs: Perfect for guest cottages or self-contained rental units, offering total privacy and flexibility.

• Attached ADUs: Extend your main home to create a suite with its own entrance and amenities—ideal for in-laws or multi-generational living.

• Garage Conversions: Make use of underutilized space by converting your garage into a beautiful living area.

• Above-Garage Units: Great for elevated views and efficient use of space, these units provide a quiet, private retreat.

• Custom Retreats & Studios: Yoga rooms, wellness spaces, home offices, art studios—tailored to your lifestyle and the natural surroundings.

We design with both form and function in mind, ensuring your ADU feels like a seamless extension of your estate.

How Much Does It Cost to Build an ADU in Portola Valley?

ADU costs in Portola Valley can vary depending on property conditions, design goals, and finish level. In general:

• Garage Conversions: $150,000 – $200,000+

• Attached ADUs: $250,000 – $400,000

• Detached ADUs: $300,000 – $600,000+

• Custom Luxury Builds: $500,000 and up

Your investment is influenced by:

• Site conditions (grading, access, trees, slopes)

• Foundation work and utilities

• Architectural design complexity

• Interior finishes and smart home features

• Eco-conscious building techniques

• Permit and development fees

We’ll provide a detailed, transparent quote and help you plan a budget that fits your vision and lifestyle goals.

ADU Permit Process in Portola Valley

Portola Valley places a strong emphasis on design harmony, sustainability, and environmental impact. We’re well-versed in working with the Architectural & Site Control Commission (ASCC) and other local agencies to secure approvals efficiently.

Here’s what our team handles for you:

• Site evaluation and zoning compliance

• Preparation of complete plan sets

• Submissions to Portola Valley planning and building departments

• Environmental and tree protection assessments, if needed

• Coordination with town officials and fast response to revisions

With Royalty Builders, you can trust that your ADU will be designed and built in full alignment with Portola Valley’s standards.

Frequently Asked Questions – ADU Services in Portola Valley

Q: Can I build an ADU on a sloped lot in Portola Valley?
A: Yes, but it may require grading, retaining walls, or custom foundation work. We specialize in hillside and challenging terrain construction.

Q: What size ADU can I build?
A: Most ADUs can be up to 1,200 sq. ft., depending on your lot size and the town’s guidelines. We’ll help you determine what’s possible.

Q: How long does the process take?
A: From design to move-in, it typically takes 8–12 months, including permitting, planning, and construction.

Q: Are ADUs allowed in scenic or conservation areas?
A: In many cases, yes—with careful planning. We’ll review your property and work with local authorities to ensure full compliance.

Q: Can my ADU include green building features?
A: Absolutely. We can incorporate solar panels, energy-efficient windows, low-impact foundations, and more to support sustainability.

Why Choose Royalty Builders for Your Portola Valley ADU?

• 🌲 Expertise in Natural & Rural Settings

• 🏗 Design + Build Under One Roof

• 🛠 Exceptional Craftsmanship using durable, elegant materials

• 📝 Knowledge of Local Permitting & Design Review

• 🏡 Custom Designs that Respect the Landscape

• ✅ Proven Results & Satisfied Clients Across the Bay Area

We approach every project with care, creativity, and a commitment to excellence—because your home deserves nothing less.

Ready to Build an ADU in Portola Valley?

Whether you’re adding a guest house, wellness studio, or private rental unit, Royalty Builders is your trusted partner for ADU construction in Portola Valley. Let us help you design a beautiful, high-quality structure that enhances your land and lifestyle.

Call us today and schedule a free consultation.