If you need extra living space for family, guests, or rental income, GCO General Contractors is here to help. Based in San Bernardino, CA, and serving all of California, we build accessory dwelling units (ADUs), room additions, and garage conversions that fit your needs and budget. Our experienced team manages the entire process, from planning and permits to construction and finishing touches.


Adding an ADU or new room is a smart way to increase your home’s value and make life more comfortable, all without moving. With GCO General Contractors, expanding your space is simple, safe, and reliable.


Get in touch now for expert advice and a free quote on your ADU or addition.

Customized ADU Solutions and Room Additions for Every Home

We provide a range of solutions to help you add living space, comfort, and value to your property. Whether you need a new living unit for family, a private rental, or simply more room, our team will guide you through every step of the process.

Detached ADUs

We design and build standalone accessory dwelling units in your backyard or on your lot. These units are perfect for guests, in-laws, or as rental spaces. Each ADU is built to match your needs and blend with your existing property.

Room Additions

If you need an extra bedroom, office, or expanded living area, we can add square footage to your home with thoughtful, seamless additions. We work closely with you to create spaces that feel like they’ve always belonged in your house.

Garage Conversions

Looking to make better use of your garage? We convert garages into comfortable living spaces, studios, or second units, giving you more flexibility without taking up yard space.

Benefits of Adding an ADU or Home Addition

Expanding your living space with an ADU or addition offers many advantages for California homeowners. ADUs are perfect for multi-generational living, creating guest space, or generating extra income through rental opportunities. Room additions let you accommodate a growing family, work from home, or add new features like a master suite or home office. Both options increase your property’s value, flexibility, and overall comfort, all without the hassle of moving.

Frequently Asked Questions About ADUs and Home Additions

  • How long does it take to build an ADU or home addition?

    Most projects are completed in a few months, depending on size and design. We provide a clear timeline before we start.

  • Do you help with permits and local regulations?

    Yes, our team handles all permits and ensures your ADU or addition meets California codes and requirements.

  • Will an ADU increase my property value?

    In most cases, adding an ADU or room addition will boost your property value and create more opportunities for rental income or family use.

  • Can I customize the design?

    Absolutely. We help you design your new space to match your needs and preferences.

Reach out today for a free estimate and personalized planning for your new space.