Designing Your Dream ADU in Santa Rosa, CA: A Guide for Homeowners

Oct 21, 2024

Are you considering adding an Accessory Dwelling Unit (ADU) to your property in Santa Rosa? Whether it’s for additional rental income, space for family, or a creative studio, an ADU offers exciting possibilities. As designers, we aim to help you build a unit that not only complies with local regulations but also enhances your home’s functionality and value. Below, we walk through the key requirements, advantages, and design considerations to ensure your ADU project is a success.

What is an ADU and Why Build One?

An ADU is a secondary, self-contained living unit located on the same lot as a primary residence. Often called granny units, ADUs come in many forms: detached structures, attached additions, or garage conversions. Santa Rosa’s supportive regulations allow property owners to explore these small homes while contributing to housing availability.

The benefits of building an ADU are plentiful. With housing demand rising in California, ADUs offer flexible living spaces for family members or long-term tenants. Santa Rosa even allows short-term rentals over 30 days, making it a perfect option for additional income.

Key ADU Requirements in Santa Rosa

Santa Rosa has straightforward regulations to guide homeowners through the process. These standards keep development efficient while ensuring ADUs fit seamlessly into neighborhoods. Below are the primary rules that will shape your design and planning efforts.

1. Zoning and Lot Requirements

ADUs are permitted in many zoning districts, including residential zones. A critical requirement is that the ADU must be on the same lot as a primary residential structure. Whether you’re in a single-family or multi-family zone, Santa Rosa offers opportunities for various ADU types.

Lot Size and Prohibitions Areas:

• There is no minimum lot size to establish an ADU.

• Lot coverage limitations cannot prevent the construction of an ADU up to 800 square feet, as long as it complies with height limits and maintains a four-foot setback from the side and rear property lines.

• ADUs outside the city limits are not allowed on lots with “Z” zoning or those subject to Williamson Act contracts.

  • Unincorporated county zoning can be found on Zoning & Land Use Map

This flexibility allows property owners to make the most of their space while ensuring the ADU complements the main home.

2. Size Limits for ADUs

The size of your ADU will depend on the type you are building. The minimum ADU size for all is 150 square feet:

• Detached ADUs: Maximum size is 1,200 square feet.

• Attached ADUs: Maximum size is 1,200 square feet.

• Converted ADU’s: The structure can be expanded by up to 150 square feet for entry and exit purposes. Larger additions are allowed, up to a total unit size of 1,200 square feet, but must comply with new construction standards or restrictions for nonconforming structures as outlined in the Zoning Code.

* These area limits do not include garages or accessory structures.

The flexibility in size means you can customize an ADU to suit your family’s needs, whether it’s a cozy guesthouse or a spacious rental.

3. Setback Requirements

Santa Rosa’s setback regulations are designed to ensure privacy and maintain neighborhood aesthetics. These rules vary depending on your property and ADU design:

• Rear and Side Setbacks: A minimum of 4 feet is required.

• Front Setback: The ADU must be at least 20 feet from the front property line (if applicable).

These relaxed setbacks make it easier to build in backyard spaces, leaving room for landscaping or outdoor areas.

4. Height Restrictions and Design Considerations

To ensure ADUs remain compatible with the surrounding neighborhood, Santa Rosa enforces height limits:

• New construction detached ADUs: For lots with a single-family home, detached ADU’s follow the height limit for ‘accessory structures’ established by the base zoning district's rules or a minimum of 18 feet. For ADU’s on lots with multi-family homes, the height limit is 18 feet.

• ADUs attached to or converted from primary residence: ADU’s follow the height limit for ‘primary structures’ established by the base zoning district's rules or a minimum of 18 feet.

• ADUs attached to or converted from accessory structure (garage, pool house, etc.): ADU’s follow the height limit for ‘accessory structures’ established by the base zoning district's rules or a minimum of 18 feet.

We can work within these guidelines to design a structure that complements your home while maximizing natural light, privacy, and outdoor access. Thoughtful touches such as sloped roofs or matching exterior finishes will blend the ADU seamlessly into your property.

5. Parking Requirements

Parking regulations for ADUs depend on the unit size and location:

• One off-street parking space is required for larger ADUs. (Can be located in setbacks

• Exemptions: No parking is required if the ADU is:

  • Located within ½ mile walking distance to transit stop

  • Lot is zoned HD (Historic District) Combining Zone

  • ADU is part of proposed or existing primary residence or existing accessory structure •

  • On-street parking permits are required, but not offered to ADU

  • Located within one block of a car share program

  • ADU is a studio unit

With many exemptions in place, smaller ADUs are especially easy to integrate into properties without disrupting the existing parking layout.

6. Rental and Occupancy Rules

While Santa Rosa welcomes ADUs for rentals, it restricts short-term stays to avoid the challenges associated with vacation rentals:

• Minimum Rental Period: 30 days.

• Owner Occupancy: For JADUs, the homeowner must live on-site, either in the main home or the JADU.

This ensures ADUs contribute to long-term housing needs, providing reliable rental options while fostering vibrant communities.

The Building Process: From Design to Approval

Designing and building an ADU involves several steps, but as designers, we will guide you from start to finish. Here’s an outline of the process to help you visualize the journey:

1. Initial Consultation and Design:

   • We begin by evaluating your property and discussing your goals. Together, we’ll choose the right type of ADU—detached, attached, or converted—and create initial design concepts.

2. Site Planning and Permitting:

   • We’ll handle site plans and ensure the design meets all city codes, including setback, height, and parking requirements.

3. City Review and Permits:

   • Santa Rosa requires building permits for ADUs. We’ll submit the plans and work closely with city officials to obtain approval, ensuring compliance every step of the way.

4. Construction:

   • Once permits are in place, we’ll move into the construction phase, working with trusted contractors to bring your ADU to life.

5. Final Inspection and Move-In:

   • After construction, the city will conduct a final inspection. Once approved, your ADU will be ready for occupancy!

How We Can Help You Build the Perfect ADU

As designers, we’re committed to making the ADU design and building process smooth and enjoyable. With our expertise, you’ll avoid common pitfalls like costly delays or design missteps. We’ll ensure your ADU complies with Santa Rosa’s regulations while creating a space that adds beauty, function, and value to your property.

Our approach emphasizes tailored design—whether you need a compact JADU, a detached guesthouse, or a rental unit with curb appeal. We’ll work closely with you to align the design with your lifestyle and investment goals.

Conclusion: Let’s Get Started on Your Santa Rosa ADU

Building an ADU in Santa Rosa is a rewarding investment, offering both personal and financial benefits. With reasonable setback requirements, flexible size limits, and multiple exemptions from parking rules, it’s never been easier to enhance your property with a well-designed ADU.

We’re here to help you turn your vision into reality. Whether you’re looking for more space for family or additional income from rentals, an ADU can meet your needs while adding lasting value to your home. Let’s start planning your perfect ADU today!

If you're ready to explore your options, contact us for a consultation. Together, we’ll create an ADU that exceeds your expectations.