ADU Construction in Cupertino, CA

More space for your family, more value for your home, right here in Cupertino.

Here's Why Cupertino Homeowners Choose MA Legacy Remodeling for Their ADU

If you’ve been sitting on the idea of an ADU for a while now, wondering whether it’s actually worth it or just a whole lot of hassle, we hear you. We’ve had that exact conversation hundreds of times with homeowners all over Cupertino, and the answer, more often than not, surprises them.

We build ADUs that work hard for the people who live in them. Garage conversions, detached units, attached additions, in-home ADUs, granny flats, and fully custom builds, whatever fits your property and your life. Every project gets a 5-year workmanship warranty because we’re not interested in cutting corners and hoping you don’t notice. We’re interested in doing this right, once.

See Our Work in Cupertino, CA

Take a look below at some of the ADU projects we’ve completed across the area. Every photo tells a bit of a story: the conversations we had, the challenges we worked through, and the finished space that someone is now actually living in. Browse the gallery and get a feel for the level of craftsmanship we bring to every job.

10

years of remodeling experience

5

– year workmanship warranty

What People in Cupertino, CA Say About Us

We think the best way to understand what working with us is actually like is to hear it from the people who’ve been through the process. The reviews below come from real Cupertino homeowners who trusted us with their homes. Have a read through, and see for yourself.

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How Much Does ADU Construction Cost in Cupertino, CA

ADU pricing in the Bay Area varies quite a bit depending on what you’re building, and we want to give you real numbers, not vague ranges designed to get you on a call. Here are a few examples based on actual past projects in the area. Keep in mind, these are estimates from completed work, and your project will have its own specifics that affect the final number.

600 sq. ft. Detached ADU in Cupertino: This was a full ground-up build with foundation, framing, an open-concept floor plan, stucco exterior, a complete kitchen, full bathroom, and all the electrical, plumbing, and HVAC to go with it. We also did exterior hardscaping, a walkway, and landscaping. A project like this starts at $220,000, with the foundation and structural framing being the largest cost driver.
400 sq. ft. Second-Story Bedroom Addition in Los Altos: This project added a full second story above an existing structure, which required reinforcing the lower level first. Vaulted ceilings, exposed beams, hardwood floors, new windows, and full HVAC integration. Pricing for this kind of addition starts at $250,000 and can reach $400,000 depending on finishes and what the existing structure requires.
180 sq. ft. Living Room Bump-Out in Sunnyvale: A bump-out that extended the exterior wall, opened up the living room with large windows and vaulted ceilings, and tied seamlessly into the existing roofline and flooring. These start at $120,000 and can go up to $190,000 based on materials and scope.

Five Factors That Affect Your Final Cost

Size and Scope: A 300 sq. ft. studio ADU and a 700 sq. ft. two-bedroom unit are completely different projects, even if they feel similar on paper. Larger footprints mean more materials, more labor, and more time. Every square foot adds up, and it's worth being clear about what you actually need before getting too attached to any number.
Type of ADU: A garage conversion tends to cost less than a ground-up detached ADU because the structure is already there. An attached addition sits somewhere in between. The type of build you choose shapes the budget more than almost anything else.
Site Conditions: Some lots in Cupertino are straightforward. Others have sloped terrain, drainage considerations, or existing structures that need to be worked around. A site visit tells us things a conversation can't, and it often changes the estimate significantly.
Finishes and Materials: Standard finishes and premium finishes can be tens of thousands of dollars apart on the same build. We'll walk you through the options without pushing you toward anything, and help you figure out where spending more actually matters versus where it doesn't.
Permits and Local Requirements: Cupertino has its own permitting process and development standards, and navigating those takes time and experience. Permit costs are a real part of your budget, and so is the time it takes to get approvals in place. We handle all of this for you.

All pricing above reflects past project estimates. Your project will have its own details that change the final number. Reach out with your specifics and we’ll put together an accurate quote for you.

Budgets and Timelines, Both Taken Seriously

We know that handing over a significant chunk of money for a construction project, and trusting strangers to show up on schedule and deliver what they promised, takes a real leap of faith. We take both sides of that seriously.

An ADU in Cupertino adds real, lasting value to your property. At $220,000 on the lower end, spread across the life of the space, whether you’re generating rental income, housing a family member, or simply gaining square footage in one of the most expensive housing markets in the country, the cost looks very different when you account for what you’re actually getting in return. This is an asset, not an expense.

Construction can feel like controlled chaos from the inside, but from where we stand, it’s a schedule with milestones. We’ve built our process to move efficiently, communicate proactively, and keep disruption to a minimum. We respect that this is your home and your daily life. We clean up after ourselves, we hit our deadlines, and when something unexpected comes up, we tell you about it before it becomes your problem.

How the ADU Construction Process Works in Cupertino

Working with us is genuinely straightforward. You bring the idea, we handle the rest.

1. Plan

We sit down together, understand your goals, and map out a build that fits your property and your budget.

2. Build

Our crew gets to work, and we keep you informed throughout without burying you in decisions you didn’t sign up for.

3. Live

You settle into a finished, permitted, well-built space that adds real value to your home and your life.

FAQs About ADU Construction in Cupertino, CA

Do I need a permit to build an ADU in Cupertino?

Yes, and getting it right matters. Cupertino follows California state ADU law, which has relaxed quite a bit over the past few years, but local requirements still apply for setbacks, height limits, and utility connections. We handle the permit process from start to finish, so you don’t have to spend your evenings reading municipal code.

How long does it take to build an ADU in Cupertino?

It depends on the type of build. A garage conversion can move faster than a ground-up detached unit. Generally, you’re looking at anywhere from four to twelve months when you factor in design, permitting, and construction. We’ll give you a realistic timeline during our initial conversation, not an optimistic one designed to win the job.

Can I rent out my ADU?

Yes. In California, ADUs can be rented out as long-term housing. Many of our clients in Cupertino build their units specifically to generate rental income, which helps offset the cost of construction over time. We’d encourage you to look into local rental regulations as well, but from a construction standpoint, we build units that are fully code-compliant and ready to rent.

What's the difference between a detached ADU and a garage conversion?

A detached ADU is a freestanding structure built separately from your main home, typically in the backyard. A garage conversion takes your existing garage and transforms it into livable space. Garage conversions generally cost less because the foundation and structure are already in place, but they do require giving up your garage. Both are solid options depending on your priorities and your lot.

Miguel

Your Property Has More Potential Than You Think

An ADU construction changes more than your property value. It changes your options. Maybe that means a parent lives closer. Maybe it’s rental income that actually moves the needle. Maybe it’s a space for your own work that doesn’t bleed into the rest of your home life. Whatever the reason, the best time to get the process going is before you’ve spent another six months thinking about it.

Give us a call at (408) 545-8413 or contact us here and let’s figure out what makes sense for your property. No pressure, just a real conversation with people who know this work.

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Cupertino sits in the heart of Silicon Valley, home to Apple Park and surrounded by the natural beauty of the Rancho San Antonio Open Space Preserve. The City of Cupertino has been ahead of the curve on ADU-friendly policy, making it one of the better places in California to expand your home. ADU construction in Cupertino fits naturally into a community that values smart use of space and long-term investment.