Belmont ADU Belmont ADU Checklist Belmont ADU Floor Plans

Belmont ADU Zoning And Building Standards

This resource is designed to provide homeowners with the essential information needed to add Accessory Dwelling Units (ADUs) to their properties while ensuring compliance with local regulations. Whether you’re looking to expand your living space, create a rental unit, or accommodate family members, understanding Belmont’s ADU guidelines is crucial for a successful project.

Our team of experts is dedicated to providing you with the guidance and support you need to navigate the complexities of ADU development in Belmont. From initial planning and design to obtaining necessary permits and meeting building standards, we are here to ensure your project complies with all local requirements. Our goal is to make the process as seamless and stress-free as possible, helping you create a functional and aesthetically pleasing ADU.

Belmont ADU Zoning and Building Standards

Property Requirements

Properties in Belmont must meet specific zoning and building standards to accommodate ADUs. These regulations are put in place to ensure safety, functionality, and harmony within Belmont’s residential neighborhoods. Understanding these requirements is the first step in planning your ADU project.

Building Size

ADUs in Belmont must adhere to size restrictions to ensure they fit within the character of the neighborhood and do not overwhelm the existing property. The size of your ADU can range from a minimum of 150 square feet to a maximum of 1,200 square feet, depending on the property’s zoning and existing structures. This range allows for flexibility in design while maintaining the residential scale.

  • Single-Family Zoned Lots:

Single-family zoned lots in Belmont allow for the construction of one ADU per lot. This can be either an attached or detached unit, providing flexibility in how you choose to integrate the ADU with your existing home. The goal is to enhance the property while maintaining the neighborhood’s residential character.

  • Duplex Family Zoned Lots:

Duplex family zoned lots can accommodate two ADUs, one for each unit of the duplex. This increases housing options and provides additional living space without significantly altering the existing duplex structure. It’s a great way to maximize the use of your property and provide additional rental income or living space for extended family.

  • Multi-Family Zoned Lots:

Multi-family zoned lots support multiple ADUs, making them ideal for properties that already house multiple families. These ADUs must comply with zoning and density requirements, ensuring they fit within the overall property layout and do not create overcrowding.

  • Attached ADUs:

Attached ADUs share a wall with the primary residence, creating a seamless integration between the new unit and the existing home. This type of ADU is ideal for those looking to maintain a cohesive architectural style and efficient use of space.

  • Detached ADUs:

Detached ADUs are separate structures built on the same property as the primary residence. They offer privacy and additional living space without impacting the main residence. Detached ADUs can be used as guest houses, rental units, or separate living quarters for family members.


In Belmont, either the main residence or the ADU must be owner-occupied. This requirement ensures proper property management and contributes to community stability by maintaining a sense of ownership and responsibility among residents.

Number Of Units Allowed

The number of ADUs allowed on a property in Belmont depends on the zoning designation. Typically, single-family lots can have one ADU, while multi-family properties can support multiple ADUs, subject to specific zoning rules. This regulation helps balance the need for additional housing with the preservation of neighborhood character.

Belmont Building Height

The height of ADUs in Belmont is regulated to ensure they blend harmoniously with the surrounding neighborhood. These regulations help maintain the aesthetic consistency and prevent new structures from overshadowing existing homes.

  • Single-family: For single-family lots, the height of ADUs is generally limited to 16 feet. This restriction ensures that the ADU complements the primary residence and does not dominate the landscape.
  • Duplex family: On duplex family lots, ADUs may have height restrictions up to 25 feet. This allows for two-story designs if necessary, providing flexibility in architectural style while ensuring the new structure fits within the neighborhood’s scale.
  • Multi-family: Multi-family ADUs can vary in height, but generally, they should align with the primary structure’s height. This consistency helps maintain the aesthetic balance and ensures that the ADUs are in harmony with the existing buildings.

Belmont Building Size

The size of ADUs in Belmont is regulated to ensure they complement the primary residence and maintain the neighborhood’s character. These regulations help create a balanced living environment that accommodates additional housing without overwhelming the area.

  • Single-Family Freedom: Single-family lots typically allow ADUs up to 1,200 square feet. This size provides ample space for comfortable living quarters, whether used for rental purposes, guest accommodation, or family members.
  • Duplex house: Duplex properties may have ADUs sized up to 1,000 square feet. This size strikes a balance between providing additional living space and maintaining the duplex’s existing structure and layout.
  • Multi-Family Mix: Multi-family lots can support multiple ADUs, each adhering to size regulations that fit the property’s layout and zoning. This flexibility allows property owners to maximize their living space while complying with local building standards.

Fire Safety Regulations

Fire safety regulations are critical for ADUs to ensure the safety of occupants. These regulations include requirements for smoke detectors, fire extinguishers, and accessible emergency exits. Compliance with fire safety standards helps protect both the new ADU and the existing property.


Belmont requires adequate parking for ADUs to prevent street congestion and maintain neighborhood harmony. Typically, one parking space per unit is required, but this can vary based on the property’s location and zoning. Ensuring sufficient parking helps mitigate potential issues with increased vehicle traffic.

Utility Connections

ADUs need separate utility connections for water, sewer, and electricity. This ensures independent functionality and compliance with building codes. Proper utility connections are essential for the safe and efficient operation of the ADU, providing all necessary services without overburdening the existing infrastructure.


Setback regulations for ADUs dictate the distance from property lines, typically requiring a minimum of four feet from the side and rear property boundaries. These setbacks ensure that ADUs do not encroach on neighboring properties and maintain a respectful distance from property lines.

Zoning Regulations

Belmont’s zoning regulations ensure that ADUs complement the existing neighborhood, balancing density and residential character. Understanding these regulations is crucial for planning a compliant ADU project.

Belmont ADU Zoning Regulations

Single Family

Single-family zoning allows for one ADU per lot, ensuring the property remains primarily residential. This zoning designation helps maintain the character and scale of single-family neighborhoods while providing additional housing options.

Duplex Family

Duplex family zoning supports two ADUs, offering additional living space without overcrowding the lot. This zoning designation is ideal for properties that can accommodate more than one unit, providing flexibility for property owners.


Multi-family zoning permits multiple ADUs, enhancing housing options while adhering to density and zoning requirements. This zoning designation allows for a variety of living arrangements, making it a versatile option for property owners.

RF Zone Minimum Lot Area In Belmont

In Belmont’s RF Zone, minimum lot sizes range from spacious single-family homes (RF-20) to sprawling estate properties (RF-40), ensuring ample space for your ADU and lifestyle. These lot size requirements help maintain the character and scale of the neighborhood.

  • RF-20: Minimum lot size of 20,000 square feet, ideal for single-family homes with ample ADU space. This lot size provides flexibility for larger ADU designs and additional outdoor space.
  • RF-30: Minimum lot size of 30,000 square feet, providing more room for larger properties and ADUs. This lot size allows for greater flexibility in ADU design and placement.
  • RF-40: Minimum lot size of 40,000 square feet, suited for estate properties with expansive ADU possibilities. This lot size ensures that ADUs can be designed and placed to complement larger properties and provide ample living space.

Room Specifications

ADU room specifications ensure functionality and comfort for residents. The following table outlines the essential standards for different room types, providing clear guidelines for designing your ADU.

Belmont ADU Room Specifications

Room TypeSpecifications
Bathroom1. Minimum size of 5×8 feet

2. Proper ventilation

3. Non-slip flooring

4. Shower/bathtub

5. Sink with adequate counter space

Kitchen1. Minimum size of 7×10 feet

2. Stove and oven

3. Refrigerator

4. Sink with hot and cold water

5. Sufficient counter and storage space

Sleeping Areas1. Minimum size of 10×12 feet

2. Egress window for emergency exit

3. Closet or storage space

4. Heating/cooling system

5. Adequate electrical outlets

Storage1. Minimum size of 4×6 feet

2. Built-in shelving

3. Adequate lighting

4. Secure door with lock

5. Proper ventilation to prevent mold and mildew

Belmont Requirements

Belmont has specific requirements for ADUs, ensuring they fit within the community’s character and comply with all local regulations. These requirements cover various aspects of ADU design and construction, providing a framework for successful projects.

Detached ADU Belmont: Detached ADUs must comply with zoning and setback regulations, offering a private living space separate from the main residence. These units provide flexibility in design and use, making them a popular choice for homeowners looking to add value to their property.

Attached ADU Belmont: Attached ADUs integrate with the primary residence, sharing at least one wall. They must comply with specific building codes and standards, ensuring they blend seamlessly with the existing structure and maintain the architectural style.

JADU Belmont: Junior ADUs (JADUs) are smaller units within the main residence, typically limited to 500 square feet. These units offer a cost-effective housing solution, providing additional living space without the need for extensive construction. JADUs are ideal for accommodating family members or creating a small rental unit.

Rental Requirements

Belmont has specific rental requirements for ADUs to ensure tenant safety and compliance with local regulations. These requirements help protect both the property owner and the tenant, creating a safe and stable rental environment.

  • Proof of income: Tenants must provide proof of stable income, such as pay stubs or tax returns, ensuring they can meet rental obligations. This requirement helps property owners assess the financial reliability of potential tenants.
  • Credit score: A minimum credit score is required to demonstrate financial reliability and responsibility. Property owners can use credit scores to evaluate the likelihood of timely rent payments and overall financial stability.
  • Rental history: Prospective tenants must provide a rental history, showcasing their track record as responsible renters. This history helps property owners gauge the tenant’s reliability and past rental behavior.
  • Application fee: An application fee covers the cost of processing rental applications and background checks. This fee ensures that property owners can thoroughly vet potential tenants and make informed decisions.
  • Security deposit: A security deposit is required to cover potential damages and ensure the tenant fulfills lease obligations. This deposit provides financial protection for the property owner and can be used to cover repairs or unpaid rent.
  • Proof of renter’s insurance: Tenants must provide proof of renter’s insurance to cover personal belongings and liability. This insurance protects both the tenant and the property owner in case of accidents or damages.
  • Pet policy: Belmont ADUs may have specific pet policies, including restrictions on types and sizes of pets allowed. These policies help maintain the property’s condition and ensure compatibility with other residents.
  • Smoking policy: Non-smoking policies may apply to ensure a clean and healthy living environment. These policies help protect the property from smoke damage and create a safe space for all residents.

Development Standards For Belmont ADU

Belmont’s development standards ensure that ADUs are built to high-quality specifications, providing safe and comfortable living spaces. The following table outlines the development standards for different ADU types, ensuring compliance with local regulations.

ADU TypesDevelopment Standards Specifications
Single-family1. Max 1,200 sq. ft.

2. 16-foot height limit

3. One parking space

4. Setback compliance

5. Separate utilities

Duplex1. Max 1,000 sq. ft.

2. 25-foot height limit

3. Two parking spaces

4. Setback compliance

5. Separate utilities

Multi-family1. Max 1,200 sq. ft.

2. Height per zoning

3. Multiple parking spaces

4. Setback compliance

5. Separate utilities

Junior ADUs (JADUs)1. Max 500 sq. ft.

2. Part of main residence

3. No additional parking required

4. Setback compliance

5. Shared utilities

Belmont Property Designations For ADU

Belmont’s property designations impact where and how ADUs can be built, considering environmental and structural factors. Understanding these designations helps ensure that your ADU project complies with all local regulations and is built safely.

  • Flood zones: Properties in flood zones must comply with additional regulations to ensure safety and prevent water damage. These regulations may include elevated building requirements and additional drainage solutions.
  • Geohazard zones: Geohazard zones require special building considerations to mitigate risks like landslides and earthquakes. These considerations may include reinforced foundations and other structural enhancements.
  • Easements: Easements may impact where ADUs can be built, ensuring access for utilities and neighboring properties. Understanding and respecting easements is crucial for compliance and avoiding legal issues.

ADU Permit Requirements And Fees

Building an ADU in Belmont requires various permits, each with associated fees, to ensure compliance with local building codes and regulations. These permits cover different aspects of the construction process and help maintain safety and quality standards.

Belmont ADU Permit Requirements and Fees

  • Building Permit: A building permit is required for all ADUs, covering structural and safety standards. This permit ensures that the ADU is built according to approved plans and complies with all building codes.
  • Electrical Permit: An electrical permit ensures that all wiring and electrical work meet safety and code requirements. Proper electrical installation is crucial for the safe operation of the ADU.
  • Plumbing Permit: A plumbing permit is needed for all water and sewer connections, ensuring proper installation and compliance. This permit helps prevent plumbing issues and ensures the ADU has reliable water and sewer services.
  • Other Permits: Additional permits may be required for specific features, such as mechanical systems or solar panels. These permits ensure that all aspects of the ADU are built to code and function properly.

Design Your Dream ADU Today!

Ready to begin your ADU Journey? Our expert guidance, ensuring a smooth and compliant process from design to construction. Whether you’re looking to create additional living space, generate rental income, or accommodate family members, we are here to help you design and build the perfect ADU for your Belmont property. Let’s work together to bring your vision to life.


Yes, but specific setbacks and design considerations apply. Contact the Woodside Planning Department for detailed guidance on navigating unique lot shapes.

Some lenders offer ADU loans, but traditional home loans can also be used for ADU construction, especially if they add value to your property.

Yes! The State of California offers various ADU incentive programs, including grants for low-income homeowners and developers. Research state and local programs to see if you qualify for financial assistance.

Related Articles to Belmont