Custom Accessory Dwelling Units in the Silicon Valley

Make the most of your backyard space with a custom structure from Backyard Unlimited. Since 2009, we’ve helped homeowners throughout the Silicon Valley increase comfort, usable space, and resale value with premium quality backyard structures.

What is an ADU?

Accessory Dwelling Units or ADUs are now one of the fastest growing forms of housing in California. Thanks to recently passed state and local laws, it is easier for Californians to add a detached structure to their property for family, caregivers, or tenants. ADUs are most commonly built on single family residential lots, where many want to live, but where smaller more affordable housing is hard to find. At Backyard Unlimited, we specialize in designing and building detached ADUs. These accessory structures are legally rentable, have their own address, and can have separate utility metering if desired. ADUs are usually limited to 1200 square feet, but on average are around 750 square feet.

Benefits of Building an ADU

An accessory dwelling unit increases your property’s value since it’s an entirely separate living space. This new livable space officially adds, square footage, bedrooms and bathrooms to the county record of your home’s parcel and is an area that can be covered by homeowner’s insurance. You can also legally rent out your ADU, as a way to earn additional income.

You can fully customize your ADU with the same high-quality materials that you would use in your own home. Unlike finished sheds, ADUs can have multiple rooms including a kitchen, bathroom, and bedroom – each outfitted and furnished as well as a room in a full-sized home. Everything is built to code and fully-permitted, using building-grade materials designed to last for over 50 years.

We’ve seen our customers use their ADUs in extremely creative ways including:

  • A small home for an aging relative
  • A place for an adult child to live, work, and have their own space
  • Downsizing to age-in-place while family moves into larger house
  • Rental property or Airbnb for supplemental, passive income

Additional ADU Benefits

Reduce infrastructure impact on cities – ADUs use existing roads, utilities, and land without a need for cities to begin expensive infrastructure expansion projects.

Good for the environment – ADUs tend to be smaller than comparable rental units. This means they need less energy to heat and cool. They take less material to build, and require less time, energy, and materials to clean and maintain. When talking about the environment, less is more.

Keep families close together – multigenerational households help families find family-based options for child-care and elder care previously unavailable.

Adu Guide 2024

Have ADU Questions? Get Answers from the Experts

We’ve compiled our years of experience building prefab structures into The Ultimate Guide to ADUs in California. In this guide, you’ll learn everything you need to know about the ADU process – from planning & permitting to designing & construction.

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ADU Builder in Silicon Valley

Based in Sacramento, Backyard Unlimited delivers and installs custom structures throughout the Silicon Valley, including San Jose, Sunnyvale, San Mateo, Palo Alto, Redwood City, Pacifica, Mountain View, and Cupertino.

About Backyard Unlimited

Regulations for Building an ADU in Silicon Valley


Silicon Valley ADU Building Requirements

Specific laws and guidelines govern ADUs, and the laws can vary based on municipality.

Two major requirements for ADUs are: 1) the structure must be fewer than 1,200 square feet; 2) the property owner must reside in either the main residence or the ADU.

Check with your local government or visit their website to see the regulations that apply to your project. We’ve provided information for a few areas within the Silicon Valley below.


San Jose ADU Requirements

The City of San Jose has put together a guide of useful information and regulations to help you get started building an ADU.

San Jose ADU Guide

Palo Alto ADU Requirements

Check out the City of Palo Alto’s planning and development page, which has all of the information and regulations in regards to building an ADU in Palo Alto.

Palo Alto ADU Regulations

San Mateo ADU Requirements

The City of San Mateo has put together a guide of resource and information to help you get started with building an ADU.

San Mateo ADU Info

Pacifica ADU Requirements

Check out the City of Pacifica’s handout on the zoning and planning regulations regarding building an ADU in Pacifica.

Pacifica ADU Handout

Featured ADU Project: Inverness Drive, Pacifica

This recent project in Pacifica, California is a 560 square foot ADU. This structure measures 20′ x 28′ and features 2 bedrooms, 1 bath, a full kitchen, and an attic for additional storage.

See Project Details

Happy Customers

“I found Backyard Unlimited on the web in 2019. I was immediately drawn to them because of their ability to do drawing submittals as well as the construction of an ADU. It was a one stop shop and now that my ADU is complete I can say I am very satisfied with the service, quality and most importantly their ability to honor the price that was in contract. The permitting and plan submittal was the most time consuming part of the process and it did have to do with me requesting a major change in the plans due to new setback rules that would benefit my ADU. Max was supportive and understanding of the changes and once I finally got the permit, it was a matter of scheduling to break ground. Unfortunately it was rainy season and covid which delayed the start. Once it started, things progressed and inspection with city inspectors went well. Because the ADU was in the peninsula in San Mateo County, the scheduling was a little tricky since they drive from the Sacrameto area, but it didn’t bother me that much. What I was most looking for was for the ADU to be built properly, pass inspection, stay within budget and for them to stand behind the quality of the work. I’m happy to say, all those criteria were met. I didn’t go over budget. No major issues with the city inspector were found. I notified them of some quality corrections and they immediately acknowledged and responded which demonstrated to me they have ongoing care and pride in what they do. I would use Backyard Unlimited again in the future and I would definitely recommend them to my friends and family. Good luck on your projects.

Michael Wong (Google Review) (San Mateo, CA)

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