The ADU Size Mistake That’s Costing San Jose Homeowners Thousands at Resale

After years of representing buyers and sellers in the San Jose and Willow Glen markets, ADUs have been a hot topic among my clients. One big question they have is what does it do to their property value. While that question has many answers this post will be about how size impacts resale value!

Let me share what I’m seeing in the market for 2026, and why strategic sizing matters more than square footage.

Your ADU May Not Get You Full Value

For many buyers an ADU is a “nice to have” not a “need to have”. If you are building an ADU for a home office or in-law-suite and you expect to get the same price per square foot as you home you may be in for a surprise. Appraisers and buyers see ADUs very differently. Because many home buyres are not looking for an ADU that means that this feature becomes less valuable. Appraisers also see that on the open market your interior square footage is superior to ADU square footage for buyers.

Why Aging ADUs Are Becoming Deal-Breakers

Here’s what I’m telling my seller clients: that 1,200-square-foot ADU you built five years ago or not up to code? It’s not commanding the premium you expect. In fact, it might be reducing your buyer pool.

I’ve seen it repeatedly—buyers love the idea of an ADU, but what they don’t want is an ADU in place of other features, like a yard, or garage. If the ADU is large then maintenance also becomes a factor. Buyers that see renovations may start deducting from their offer. They’re envisioning the inevitable remodel, and they’re pricing it into their bid. 

The “Double Remodel” Dilemma.

The next generation of homeowners doesn’t want a fixer—they want turnkey, or at least manageable. An aging, oversized ADU signals deferred maintenance and future expense.

My Advice for Maximum Resale Value

After facilitating dozens of ADU-inclusive transactions, here’s my professional recommendation: build strategically, not ambitiously. A well-maintained 500-600 square foot unit will outperform an 1,000+ square foot structure that’s become a maintenance burden.

Think resale from day one. The families I represent want additional income or flexible space, but they don’t want a second home to maintain.

Don’t let your backyard investment become a selling obstacle. In this market, thoughtful planning beats square footage every time.

Questions about how an ADU impacts your home’s value in San Jose or Willow Glen? Let’s talk strategy before you build, or before you list! 

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About the Author 

With over 20 years of experience navigating the fast-paced Silicon Valley market, I provide a strategic, results-driven approach to residential real estate. My career is built on a foundation of deep local expertise and a relentless commitment to my clients’ success, resulting in over $235 million in lifetime sales volume and a consistent ranking in the top 3% of agents in Santa Clara County and top 2% at Coldwell Banker. My expertise has been featured on KTVU Fox 2, Real Producers and the Willow Glen Resident. 

A Hyper-Local Expert with Global Reach

I specialize in San Jose, in the neighborhoods of Willow Glen (95125) and Downtown San Jose/Japantown (95112) markets. As a certified Luxury Property Specialist with Coldwell Banker Realty, I combine high-end marketing strategies with granular neighborhood knowledge to help my clients achieve premium results.

The “Tiger” at the Negotiating Table

My clients have characterized me as a “tiger” at the negotiating table who remains “sweet and patient” with my clients throughout the process. I pride myself on being a fierce advocate for my buyers and sellers, ensuring the best possible terms in every transaction, and I strive to be the best Realtor in 95125! This balance, drive, and tenacity have earned me consistent 5-star ratings across Google, Zillow, Realtor.com, and Yelp.

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