Best ADU Company US - Eano

What's The Cost For Building An ADU In San Jose?



|Last Updated: 07 Apr 2024

Multifunctional spaces like ADUs and other home additions have become the trend this year.

As many Californian homeowners gear towards investing in such living arrangements, many are still wondering what actual benefits lay in store for them. Apart from high ROI, these ADU San Jose are known to instantly curb your house’s appeal and increase your home value. To some, it might still sound like you’re about to fritter away your hard-earned money. If this fear has been a dilemma for quite some time, then you’ve come to the right place. This article would provide you possible options you can choose from whenever you’ve decided to build an accessory dwelling. Let’s take a good look at these cost breakdowns and see clearly how much do we need to spend when building a San Jose ADU.

Before scouting for the best home renovation company, do a little research about the different types of ADUs first. Be mindful of the city prerequisites and permits you need to secure ahead of time. Costs may vary depending on different factors: your ADU San Jose contractors, the materials you’d like to use, and your overall ADU San Jose structure. Furthermore, other expenses may still be incurred as it’ll include permit costs, utility connections costs, design costs, and many others.

To get you started, here are three types of San Jose ADUs and their approximate costs.


Types of ADU


Attached ADU

Attached ADU

A converted space that is typically built amidst the primary dwelling’s original floor plan. It’s also known as Junior Accessory Dwelling Unit (JADU)



Cost range: $106,000 to $216,000
Square footage: 361 sq. ft. to 820 sq. ft


Detached ADU

Detached ADU

It is a type of ADU San Jose that is usually built within the confines of your backyard. It’s a separate unit that can be utilized in various ways and serve a wide range of functions and is commonly called granny flats, tiny homes, or guest houses.



Cost range: $112,000 to $285,000
Square footage: 250 sq. ft. to 800 sq. ft



Basement ADU

Basement ADU

Another practical ADU type but this is the most unique among these options. This is the only home addition that is not visible from the primary dwelling’s facade.



Cost range: $74,000 to $380,000
Square footage: 391 sq. ft. to 800 sq. ft



Garage Conversion

Garage Conversion

A low-cost option but the most popular type of ADU. It is a transformed living space that can be either an attached or detached ADU.



Cost range: $80,000 to $150,000
Square footage: 325 sq. ft. to 576 sq. ft



Now that you have an overview of the different ADU types and their costs, the next thing we need to do is to scout for reputable ADU builders, contractors, or home renovation professionals. Once you’ve found your preferred contractors, it’s time to prep for your budget as well. Here are some of the labor costs you may incur when you kick off your ADU project with professionals:


Architect and Engineers


Your San Jose ADU wouldn’t be possible without the help of a professional draftsperson. They typically charge between $100 to $130 per hour. Aside from drafting, other processes may also include:

  • Consultation and home walk-through (cost ranges from $200 to $500 within 2-4 hours)


  • Schematic floor plan designs and sketches (elevation, interior, and exterior space). During this process, you’ll make some revisions or edits that could take up to 6 to 12 hours ($600 - $1,500).


  • Permit and zoning applications: ($200 to $400)



Amid the home remodeling procedure, certain addition, alteration, and size specification are inevitable. If you have an idea what your dream ADU would look like, it is wise and always best to call for an architect. These individuals are known to translate your thoughts into a feasible plan. They’re the best person to ask regarding building codes, zoning regulations, contractor selection and they can even manage your ADU project

The average national cost of hiring an architect is $5,701 (or a cost range between $2,016 and $8,576).


Costs may differ depending on various factors:

  • The fee structure that a particular architect uses (percentage, per square foot or hour)
  • How large or complex your ADU project is
  • Your location and local regulations
  • The services your preferred architect offers draft plans, full plans, project administration, construction documents, and more.



These professionals are the primary creators of your ADU project. Their expertise is much needed as your construction plan relies heavily on their recommendations. They use scientific knowledge, mathematics, and professional insights to develop solutions. They keep the balance of brilliant design structures, systems, and materials with safety, practicality, and costs.


There are two types of engineers you’ll need for your San Jose ADU:

  • Structural Engineer

Hiring a structural engineer is a must if modifications or removal of load-bearing walls in your home are needed. They’re also the best people to call when changes have been made to the plumbing or wiring, or if other structural elements are being tampered with. In short, engineers ensure your structure’s overall design and safety. The average national cost of hiring an engineer is $501 or a cost range between $350 and $500.


  • Soil Engineer

Soil engineers or also known as “geotechnical engineers” assess the soil structure of a proposed construction site. They analyze existing structures and look for any problematic conditions concerning the ground under foundations. These engineers alleviate problems like wall cracks, moving buildings, chimneys continually going down, and others. Hiring soil engineers can range from $500 to $1,000.

We have to admit, home additions may need to take quite a chunk from your money but in the end, they’re worth it! Accessory Dwelling Units or any other home additions open up new possibilities in your lifestyle—higher ROIs, higher property resale value, and better house aesthetics. 


If you are looking for affordable home renovation or simply searching for trusted ADU contractors then Eano Home Renovation might be exactly what you need. We are a tech-enabled construction company that provides renovation projects like garage conversions and ADU building. If you're curious about how much you'll spend when building an ADU with us, drop by our website and get your free quote today!


*All images are from the internet.


Get In Touch
Thank you for visiting Eano! Subscribe now to receive free renovation tips, discounts on materials and more!

To log in, simply enter your email address—no password needed.


Learn about Eano ADU

Make the most of your backyard

Learn More


Remodeling Service


Harness the New Era of Housing Flexibility


Create Your Dream Bathroom


Small Update To Full Remodel