Gilroy is one of California’s hidden gems—known for its open spaces, welcoming neighborhoods, and growing demand for flexible housing. With the rising cost of living and changing family needs, Accessory Dwelling Units (ADUs) have become a popular way to expand living space, generate rental income, and future-proof your home.

At Royalty Builders, we specialize in building custom ADUs that complement your main house and increase your property’s value. From detached cottages and guest houses to garage conversions and attached in-law units, our team provides end-to-end service, guiding you from your initial idea to a fully finished, move-in-ready space.

Whether you’re planning an ADU for elderly parents, adult children, rental income, or your own peaceful retreat, we help you make the most of your property—efficiently, beautifully, and with minimal disruption.

🛠️ Full-Service ADU Design + Build in Gilroy

Building an ADU is more than just adding a structure—it’s about designing a smart, livable space that meets specific needs. As a full-service design + build ADU contractor in Gilroy, we manage every aspect of your project in-house. That means you’ll benefit from a streamlined process, better communication, and a single team that’s fully accountable for the result.

Here’s what’s included:

✅ Property Feasibility Assessment – We inspect your lot, setbacks, and zoning to confirm what’s possible
✅ Custom Floor Plan Design – Our designers help you plan the perfect layout for privacy, efficiency, and comfort
✅ Permit Preparation & Submission – We handle all city paperwork, including Title 24 and energy code requirements
✅ Construction & Project Management – Licensed contractors, quality materials, and a clean, respectful work site
✅ Final Inspections & Finishing Touches – From cabinetry to lighting, we make sure your ADU is turnkey and beautiful

We’ve built ADUs ranging from 400 to 1,200 square feet and can tailor every detail to your goals, budget, and timeline.

🧱 Types of ADUs We Build in Gilroy

Each property is different, and so are the reasons for building an ADU. That’s why we offer a range of solutions to match your space and needs:

🔹 Detached ADUs

A separate living unit built in your backyard—perfect for long-term rentals, Airbnb income, or independent family housing. These can range from small studios to full 2-bedroom cottages and can include full kitchens, bathrooms, and private entrances.

🔹 Garage Conversions

Turn an underused garage into a high-value living space. A garage conversion ADU offers a fast, cost-effective way to add housing without building a new foundation. Great for offices, guest suites, or income-producing rentals.

🔹 Attached ADUs

These units share a wall with your primary residence but have a private entrance and all the amenities of a separate apartment. They’re ideal for aging parents, caregivers, or multigenerational households who need proximity with privacy.

🔹 Above-Garage ADUs

An elevated apartment or studio built over your existing garage. This option maximizes space while offering privacy and a separate view-oriented retreat.

🔹 Prefab/Modular ADUs (Site Support)

If you already have a prefab ADU in mind, we can help with foundation work, grading, utility hookups, and permit coordination, so your unit is placed and ready for use in no time.

📍 Why Build an ADU in Gilroy?

Gilroy offers the perfect environment for ADUs—large lots, growing families, and flexible zoning laws. Whether your goal is personal use or investment, here’s why ADUs are a smart choice in this city:

✔️ Rental Income – With increasing demand for affordable rentals, ADUs can generate consistent monthly income.
✔️ Family Housing – Accommodate elderly parents, grown children, or extended family—comfortably and privately.
✔️ Remote Work & Flex Spaces – Use your ADU as a quiet home office, art studio, or fitness room.
✔️ Property Value – ADUs significantly boost resale value and market appeal.
✔️ Legal & Encouraged – California has passed laws supporting ADU development, and Gilroy offers streamlined approvals.

💲 How Much Does It Cost to Build an ADU in Gilroy?

ADU costs in Gilroy depend on your lot, the type of unit, the level of finishes, and utility connections. Here’s a general overview:

• Garage Conversions: from $85,000–$160,000

• Detached ADUs: range from $175,000–$350,000+, based on size and finishes

• Attached ADUs: typically $150,000–$275,000, depending on scope

• Above-Garage Units: often $225,000–$375,000 due to engineering requirements

📌 Every estimate includes labor, design, permitting, inspections, and a clear breakdown of materials. We also help you understand utility impact fees, timelines, and long-term value so you can make informed decisions.

We offer financing options and phased payment schedules to help make your project more accessible.

👷 Why Choose Royalty Builders for Your Gilroy ADU?

Royalty Builders has been serving the Bay Area for over a decade with a reputation built on quality, professionalism, and personal care. We bring this same high standard to every ADU project in Gilroy.

Here’s what sets us apart:

• 🏡 Local Experience – We’re familiar with Gilroy’s specific codes and permitting process

• ✍️ Customized Designs – No cookie-cutter solutions—just creative ideas tailored to your goals

• 🧱 Licensed Contractors – Reliable construction with structural integrity and fine craftsmanship

• 🤝 Personal Service – A dedicated project manager to guide you, answer questions, and keep you informed

• 🛠️ Start-to-Finish Support – From early planning to the final punch list, we’re with you the entire way

We don’t just build ADUs—we build livable, lovable spaces that serve you for years to come.

❓ Frequently Asked Questions – ADU Services in Gilroy

Q: Is my property eligible for an ADU in Gilroy?
A: Most single-family and multi-family residential lots in Gilroy are eligible. We’ll check your lot size, setbacks, and utility access to confirm.

Q: How long does the ADU process take?
A: Design and permitting typically take 2–4 months, and construction takes another 4–6 months depending on the scope.

Q: Will an ADU affect my property taxes?
A: Only the ADU’s added value will be reassessed—not your whole property. This often results in a modest tax increase.

Q: Can I build more than one ADU?
A: In some cases, yes. California now allows one ADU and one Junior ADU (JADU) on many single-family lots. We’ll help you explore your full potential.

📝 Permits for ADU Construction in Gilroy – What You Need to Know

One of the most important—and sometimes most overwhelming—steps in building an ADU is the permitting process. Fortunately, California has streamlined ADU laws to encourage development, and the City of Gilroy follows the state’s guidelines while maintaining a straightforward local permitting system.

At Royalty Builders, we handle the entire permitting process for you—so you don’t have to worry about paperwork, meetings with the planning department, or navigating city codes on your own.

Here’s what the ADU permitting process in Gilroy typically involves:

🔹 Zoning Verification:
We first ensure your property qualifies for an ADU under Gilroy zoning regulations. Most residential lots do, but we confirm lot size, setbacks, and access requirements upfront.

🔹 Site Plan & Design Submission:
We prepare and submit a detailed site plan, floor plan, elevations, and required documents to the City of Gilroy’s Planning and Building Division. These documents must demonstrate that your proposed ADU meets building codes, height limits, and maximum square footage rules.

🔹 Plan Review & Corrections (if needed):
The city may respond with requests for minor changes or clarifications. We handle those promptly, ensuring your plans are approved without unnecessary delays.

🔹 Building Permit Issuance:
Once your plans are approved, the city issues your building permit, allowing construction to begin. We coordinate inspections, Title 24 energy compliance, and any required engineering reports.

🔹 Final Inspection & Certificate of Occupancy:
After construction, the city performs a final inspection. Once approved, you receive your Certificate of Occupancy, and your ADU is ready for use.

✅ Royalty Builders Makes It Easy

We’re familiar with Gilroy’s ADU-specific policies, including:

• Reduced or waived impact fees for ADUs under 750 sq. ft.

• No minimum lot size for most single-family homes

• Allowance for attached, detached, and converted ADUs

• Streamlined permit timelines in accordance with California law (typically within 60 days)

Our experienced team works directly with the City of Gilroy to ensure fast, smooth approvals. Whether you’re building a detached cottage or converting your garage, we manage every detail—so your project stays compliant, on track, and stress-free.

📞 Contact Us – Start Your Gilroy ADU with Confidence

Your Gilroy property holds incredible potential—let’s help you unlock it. Whether you’re planning a detached cottage for family or a garage conversion for rental income, Royalty Builders will guide you every step of the way.

📞 Call us today and schedule a free consultation

Let’s build an ADU that adds value, flexibility, and beauty to your home.