Introduction
San Lorenzo has embraced the trend of Accessory Dwelling Units (ADUs), creating a supportive regulatory environment that balances growth with community needs. ADU Specialist Bay Area is well-equipped to navigate these regulations, ensuring your ADU project is compliant and efficient. From initial consultation to final approval, our expertise ensures a seamless ADU development experience in San Lorenzo.
Essential ADU Rules for San Lorenzo
What you can build
Maximum size
ADUs in San Lorenzo can be up to 1,200 sq ft.
Side / rear setbacks
Minimum setbacks are 4 feet from property lines.
Two stories
Two-story ADUs are permitted with specific height restrictions.
Building separation
A minimum of 10 feet must be maintained between the ADU and the primary dwelling.
Permitting timeline
Standard
Permit approval typically takes 60-90 days.
Coastal
Additional coastal review may extend the timeline to 120 days.
Zoning Regulations in San Lorenzo
San Lorenzo’s zoning regulations for ADUs ensure compatibility with neighborhood character and promote sustainable development practices.
ADU Size Limitations
| Lot Size | Single-Family (Maximum Floor Area Allowed) | Duplex and Multi-Family (Maximum Floor Area Allowed) |
| Under 7000 | 700 sq ft | Not permitted |
| 7000 - 9999 | 800 sq ft | 1 ADU + 400 sq ft per existing unit (up to 1000 sq ft max) |
| 10000 - 12999 | 900 sq ft | 1 ADU + 450 sq ft per existing unit (up to 1000 sq ft max) |
| 13000 - 19999 | 1000 sq ft | 1 ADU + 500 sq ft per existing unit (up to 1000 sq ft max) |
| 20000+ | 1000 sq ft | 1 ADU + 550 sq ft per existing unit (up to 1000 sq ft max) |
ADU Height Limitations
ADUs in San Lorenzo are limited to a maximum height of 16 feet for single-story units and 25 feet for two-story units.
Building Coverage
ADUs must not exceed 50% of the existing primary dwelling’s footprint.
Location
| Property Type | Location Requirement |
| Single-Family Homes | Attached ADUs: Must share a wall with the primary residence. |
| Detached ADUs: Must be at least 10 feet from the main dwelling. | |
| Junior ADUs (JADUs): Must be within the existing primary structure. | |
| Duplex and Multifamily | Attached ADUs: Must be integrated into the primary structure. |
| Detached ADUs: Must be at least 10 feet from the main dwelling. |
Exterior details
The exterior design of ADUs in San Lorenzo must match the primary dwelling’s architectural style, materials, and color scheme.
Parking
One parking space is required per ADU, which can be tandem or in setback areas, depending on site conditions.
Setbacks and buffer zones
ADUs must maintain a minimum setback of 4 feet from side and rear property lines, ensuring adequate space for emergency access and privacy.
Minimum Lot Area
| Lot Size | Minimum Lot Area for ADU | Description |
| Under 7000 | ADUs not permitted | Smaller lots are generally not suitable for ADUs. |
| 7000 - 9999 | 7000 sq ft | Sufficient space for standard ADU construction. |
| 10000 - 12999 | 10000 sq ft | Ideal for larger ADUs with more amenities. |
| 13000 - 19999 | 13000 sq ft | Suitable for spacious ADUs and additional units. |
| 20000+ | No minimum lot area requirement | Ample space for extensive ADU projects. |
Connection for utilities
ADUs must have separate utility connections from the primary residence, including water, electricity, and sewage systems.
Fire safety
ADUs must comply with all local fire safety codes, including the installation of smoke detectors, fire extinguishers, and proper egress windows.
Room specifications
- Sleeping Areas: Must include at least one bedroom with an emergency escape and rescue opening.
- Kitchen: A fully equipped kitchen with a sink, stove, and refrigerator is required.
- Bathroom: Must include a toilet, sink, and bathing facilities, meeting all sanitation codes.
- Storage: Adequate storage space, including closets and cabinets, must be provided.
Short-term Rentals and Home Occupations Regulations
Short-term rentals of ADUs are subject to local regulations, including registration and transient occupancy tax. Home occupations must comply with zoning ordinances and business licensing requirements.
Building Codes
ADUs must adhere to the California Building Code, including standards for structural integrity, energy efficiency, and accessibility.
San Lorenzo ADU Permit Guidelines
| Permit Type | Description | Estimated Fee |
| Building Permit | Required for ADU construction. | $2500 - $5000 |
| Electrical Permit | Necessary for electrical work. | $400 - $700 |
| Plumbing Permit | Required for plumbing installations. | $400 - $700 |
| Mechanical Permit | Necessary for HVAC systems. | $400 - $700 |
| Grading Permit | Required for site grading and preparation. | $300 - $500 |
| Site Development Permit | Necessary for land development approval. | $300 - $500 |
| Zoning Permit | Required to ensure zoning compliance. | $200 - $400 |
Property Requirements
ADUs in San Lorenzo must comply with specific property requirements, including proper utility connections, fire safety measures, and adherence to building codes.
Parking
ADUs require at least one off-street parking space, which can be tandem or in setback areas.
Front setbacks
ADUs must maintain a front setback that aligns with the primary dwelling’s front yard requirements, ensuring uniformity and neighborhood aesthetics.
Side and rear setbacks
A minimum setback of 4 feet from side and rear property lines is mandatory for all ADUs in San Lorenzo.
Open space and rear yards
ADUs should not encroach on the required open space or rear yard areas, preserving the property’s overall outdoor living space.
Properties That Qualify
To determine your property’s eligibility for ADU development, contact the San Lorenzo Planning Department.
- Verify that your property is within San Lorenzo’s jurisdiction.
- Check the specific residential zones that permit ADUs. Common zones in San Lorenzo include R-1, R-2, and R-M.
- Other General Plan designations that permit ADUs:
- Residential Mixed-Use (RMU): Allows integration of residential and commercial uses.
- Transit-Oriented Development (TOD): Supports ADU development near public transit hubs.
- Specific Plan areas: Designated zones with tailored development standards for ADUs.
Development standards
Single-family
- Attached: Must share a wall with the primary dwelling and maintain architectural coherence.
- Detached: Must be located in the rear yard and maintain a 10-foot separation from the main house.
Duplex properties
- Attached: Must integrate seamlessly with the existing duplex structure.
- Detached: Must be positioned in a manner that does not disrupt shared spaces or utilities.
Multifamily properties
- Attached: Can be constructed within existing multifamily buildings, adhering to fire and safety codes.
- Detached: Must be strategically placed to enhance property value and functionality.
Junior ADUs (JADUs)
JADUs must be located within the existing primary structure, with a separate entrance and limited to 500 sq ft.
Property designations
- Flood Zones: ADUs in flood zones must comply with additional safety and construction standards.
- Geohazard Zones: ADUs in these areas require geotechnical evaluations and adherence to specific building codes.
- Historic Designation: ADUs on historic properties must maintain the architectural integrity of the primary dwelling.
- Easements: ADUs must not encroach on existing easements, ensuring utility and access rights are preserved.
Summary
San Lorenzo offers a supportive environment for ADU development, balancing regulatory requirements with community needs. ADU Specialist Bay Area is dedicated to helping homeowners navigate these regulations, ensuring successful and compliant ADU projects.
FAQ
The maximum size for an ADU in San Lorenzo is 1,200 square feet, ensuring ample living space while maintaining neighborhood aesthetics.
Yes, two-story ADUs are permitted, provided they adhere to height limitations and setback requirements, ensuring they blend well with existing structures.
The minimum setback requirements are 4 feet from both side and rear property lines, ensuring adequate space and privacy.
The standard permitting timeline is typically 60-90 days, with coastal properties requiring up to 120 days due to additional reviews.
Yes, but short-term rentals must comply with local regulations, including registration and transient occupancy taxes.
At least one off-street parking space is required per ADU, which can be tandem or located in setback areas.
Yes, the exterior design of ADUs must match the primary dwelling’s architectural style, materials, and color scheme to maintain neighborhood harmony.
No, ADUs are not permitted on properties smaller than 7,000 square feet due to space limitations.
Yes, ADUs must have separate utility connections, including water, electricity, and sewage systems, to ensure compliance with local regulations.
ADUs are limited to a maximum height of 16 feet for single-story units and 25 feet for two-story units, ensuring they do not overshadow neighboring properties.
ADUs must adhere to the California Building Code, including standards for structural integrity, energy efficiency, and accessibility.
Yes, but home occupations must comply with zoning ordinances and business licensing requirements to operate legally within ADUs.
Contact the San Lorenzo Planning Department to verify your property’s eligibility and check specific residential zones that permit ADUs.
Yes, attached ADUs must integrate seamlessly with the existing duplex structure, while detached ADUs should be positioned to avoid disrupting shared spaces.
JADUs must be located within the existing primary structure, have a separate entrance, and be limited to 500 square feet.
ADUs in flood zones must comply with additional safety and construction standards to ensure the safety and durability of the structures.
Yes, but they require geotechnical evaluations and adherence to specific building codes to mitigate potential risks.
ADUs on historic properties must maintain the architectural integrity of the primary dwelling, ensuring historical preservation.
ADUs must not encroach on existing easements, preserving utility and access rights for all property owners.
The estimated fee for a building permit ranges from $2,500 to $5,000, depending on the scope of the project.
Yes, a zoning permit is required to ensure that the ADU complies with all local zoning laws and regulations.
ADUs must maintain a front setback that aligns with the primary dwelling’s front yard requirements, ensuring uniformity and neighborhood aesthetics.
Yes, ADUs can be developed in Transit-Oriented Development (TOD) areas, promoting sustainable living near public transit hubs.
ADUs should not encroach on the required open space or rear yard areas, preserving the property’s overall outdoor living space.
ADU Specialist Bay Area provides comprehensive services, from initial consultation to final approval, ensuring your ADU project meets all regulatory requirements in San Lorenzo.
