San Carlos ADU Guide: Local Rules and Planning Tips

Accessory Dwelling Units (ADUs) are small, self-contained housing units located on the same lot as a primary residence. They’ve gained popularity for their versatility, affordability, and ability to increase housing options in areas with limited space, such as San Carlos, California. Whether you're considering building an ADU to house family members, generate rental income, or increase your property’s value, understanding the local rules and planning tips is essential for a successful project. This guide explores the specifics of constructing ADUs in San Carlos, including local regulations, design tips, and strategies for navigating the process.

What Is an ADU?

ADUs, also known as granny flats, in-law units, or backyard cottages, are secondary housing units built on single-family or multi-family residential properties. They can take various forms, including detached structures, garage conversions, or units built within the primary residence. ADUs are popular due to their flexibility and the potential they offer for addressing housing shortages in urban areas.

Why Build an ADU in San Carlos?

San Carlos, often called the "City of Good Living," is a desirable Bay Area location. With a mix of suburban charm and proximity to Silicon Valley, it’s an ideal place for ADU construction. Here’s why:

1. Affordable Housing Solutions
   ADUs provide a cost-effective way to increase housing density without altering the neighborhood’s character. They offer an affordable option for renters and a supplemental income stream for homeowners.
2. Multigenerational Living
   Families can use ADUs to house aging parents or adult children, fostering closer relationships while maintaining privacy.
3. Property Value Boost
   Adding an ADU can significantly increase the value of your property. In San Carlos, where real estate prices are high, the potential return on investment is notable.
4. Sustainability
   ADUs often have a smaller environmental footprint than traditional housing, making them a sustainable choice for eco-conscious homeowners.

Local Rules for ADU Construction in San Carlos

San Carlos follows California’s statewide regulations for ADUs but includes additional local provisions to address community-specific needs. Here’s a breakdown of the key rules:

1. Zoning and Lot Requirements

ADUs are allowed in residential zones, but the size and type of ADU you can build depend on your lot’s characteristics:

• Lot Size: There is no minimum lot size for ADU construction under California law, but the ADU must comply with setback and coverage requirements.
• Zones: ADUs are permitted in single-family and multi-family residential zones.

2. Maximum and Minimum Size

The size of your ADU must fall within the following limits:

• Minimum Size: 150 sqft, typically for efficiency units.
• Maximum Size:
  • Detached ADUs: Up to 1,200 sqft.
  • Attached ADUs: No more than 50% of the primary residence's square footage, capped at 1,200 sqft.

3. Setbacks

Setbacks refer to the required distance between the ADU and property lines:

• Front Yard: ADUs are generally not allowed in front yards.
• Side and Rear Yards: A minimum of 4 feet.
• Conversions: Garage or existing structure conversions may not require setbacks if the original structure complies with local ordinances.

4. Height Restrictions

San Carlos permits ADUs to be up to:

• 16 feet for single-story units.
• 18 feet if located near public transit or part of a multi-story design.

5. Parking Requirements

• New ADUs: Generally, one parking space per unit or bedroom is required.
• Exemptions: Parking is not required if the ADU is:
  • Within ½ mile of public transit.
  • Part of an existing structure.
  • In a historic district.

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6. Owner-Occupancy

• As of 2020, California law temporarily lifted owner-occupancy requirements for ADUs. However, San Carlos may revisit this in the future, so homeowners should check current regulations.

7. Utilities and Impact Fees

• Utilities: New detached ADUs may require separate utility connections, but conversions often do not.
• Impact Fees: ADUs under 750 sqft are exempt from impact fees. Larger units may incur fees proportional to their size.

8. Design Standards

San Carlos enforces design standards to ensure ADUs blend with the neighborhood:

• Material Consistency: ADUs should use similar materials, colors, and roof styles as the primary residence.
• Privacy: Windows and doors facing neighboring properties may require screening or frosted glass.

Planning Tips for a Successful ADU Project

Navigating the ADU construction process can be challenging. Here are practical tips to streamline your project:

1. Research Local Regulations Thoroughly

Understanding San Carlos’s specific ADU rules is critical. Contact the city's Planning Department or consult the San Carlos ADU Handbook for the most up-to-date information.

2. Assess Your Lot and Property

Evaluate your lot’s size, shape, and existing structures to determine the best type of ADU for your needs. Consult with an architect or contractor to explore your options.

3. Set a Realistic Budget

Costs for ADU construction in San Carlos typically range from $200,000 to $500,000, depending on the size and complexity of the unit. Consider expenses like:

• Design and permitting fees.
• Construction materials and labor.
• Landscaping and utility connections.

4. Hire Professionals

Work with experienced architects, contractors, and ADU specialists familiar with San Carlos regulations. They can help ensure your project meets local codes and stays on schedule.

5. Explore Financing Options

Financing an ADU can be a significant investment. Common options include:

• Home Equity Loans: Borrow against your home’s equity.
• Cash-Out Refinancing: Refinance your mortgage to access cash.
• Construction Loans: Secure funding specifically for building projects.

6. Plan for Utilities

Factor in the cost and logistics of connecting utilities like water, sewer, electricity, and gas. Early coordination with utility providers can prevent delays.

7. Maximize Space with Smart Design

Since ADUs are small, thoughtful design is key to making the space functional:

• Use open floor plans to create a sense of spaciousness.
• Incorporate built-in storage solutions.
• Choose multi-purpose furniture to save space.

Consult our ADU specialists

The Permitting Process for ADUs in San Carlos

Building an ADU requires navigating the city’s permitting process. Here’s what to expect:

Step 1: Pre-Application

Start by reviewing San Carlos’s ADU regulations and scheduling a consultation with the Planning Department. Bring your lot information and initial design ideas to discuss feasibility.

Step 2: Design and Plans

Work with an architect or designer to create detailed plans that comply with local rules. These plans will include:

• Site layout.
• Floor plans and elevations.
• Structural and mechanical details.

Step 3: Submit Your Application

Submit your plans to the San Carlos Building Department for review. Include all required documents, such as:

• Completed permit application forms.
• Architectural drawings.
• Engineering calculations, if necessary.

Step 4: Review and Approval

The city will review your plans for compliance with zoning, building, and safety codes. Revisions may be requested before approval is granted.

Step 5: Construction and Inspections

Once your permits are approved, construction can begin. Throughout the process, the city will conduct inspections to ensure the project adheres to approved plans.

Common Challenges and How to Overcome Them

1. Budget Overruns

• Solution: Create a detailed budget with a contingency fund for unexpected expenses.

2. Design Issues

• Solution: Hire a professional designer experienced in ADUs to avoid costly mistakes.

3. Permit Delays

• Solution: Double-check your application for completeness and accuracy before submission.

4. Neighborhood Concerns

• Solution: Communicate with neighbors about your plans and address their concerns to maintain goodwill.

Future Trends in ADUs

ADUs are evolving to meet modern housing needs. In San Carlos, future trends include:

• Sustainability: Expect more ADUs featuring energy-efficient materials and solar power.
• Technology Integration: Smart home features like automated lighting and security systems are becoming popular.
• Prefabricated ADUs: Modular and pre-built units are reducing construction times and costs.

Final Points

Building an ADU in San Carlos can be a rewarding investment, providing additional living space, income potential, and increased property value. By understanding local rules and following the planning tips outlined in this guide, you can navigate the process with confidence. Whether you’re constructing a small studio or a spacious two-bedroom unit, your ADU can enhance your lifestyle while contributing to the city’s housing solutions.

For detailed guidance, consult San Carlos’s Planning Department and work with professionals experienced in ADU construction. With careful planning and execution, your ADU project can become a valuable addition to your property.

Consult our ADU specialists