Millbrae ADU Checklist

ADU Building, Zoning, and Design Regulations in Millbrae

Planning an Accessory Dwelling Unit (ADU) in Millbrae presents exciting possibilities for homeowners interested in creating additional living space, generating income, or accommodating aging family members. Understanding the city’s specific regulations regarding number of units, zoning requirements, and design considerations is crucial to ensure a smooth and successful building process.

Number of Units

Millbrae generally allows one or two ADUs on single-family residential properties, depending on existing dwelling units and ADU type (attached, detached, converted, or junior). Multi-family properties have specific allowances based on building configuration and zoning.

Zoning Regulations

Each zoning district in Millbrae has specific regulations regarding ADUs. Some common district types include R-1 (Single-Family Residential), R-2 (Multi-Family Residential), and C (Commercial). Millbrae imposes size restrictions on ADUs, typically ranging from 500 to 1,200 square feet depending on the zoning district and ADU type. Ensure your planned ADU adheres to these limitations.

Single-family Properties

Generally, single-family properties in Millbrae can host one detached ADU or two total ADUs (including attached options or Junior ADUs within existing structures). Attached ADUs must not exceed 50% of the existing living area and typically cannot exceed two stories.

Detached ADUs can reach 16 feet in height, while attached units have a 25-foot limit. Size allowances depend on the ADU type, with detached units capped at 1,200 square feet and Junior ADUs limited to 500 square feet.

Duplex or Multi-Family Properties

While constructing an ADU on a single-family home comes with its rules, the landscape shifts when your property is a duplex or a multi-family building. Additional units might not be permitted if your duplex or multi-family building already has an ADU. Each zoning district has limitations on the total number of dwelling units allowed per lot.

Converting existing spaces within your duplex or multi-family building into an ADU might be viable. Junior ADUs, typically studios or one-bedroom units within a larger structure, offer flexibility without additional construction.

Millbrae Requirements

Find out more here, Millbrae ADU Forms & Handouts

Setback Requirements

Building any structure in Millbrae necessitates adhering to specific setback regulations, defining the minimum distance a structure must be set back from property lines and features like streets and sidewalks. These regulations ensure adequate space for light, ventilation, fire safety, and overall neighborhood livability.

For Accessory Dwelling Units (ADUs), the setback requirements vary depending on the type of ADU and your property’s zoning district. Detached ADUs typically require a minimum of 4 feet from side and rear property lines, while attached ADUs might adhere to slightly different distances based on specific zoning regulations.

ADU Size Requirements

ADU Height Requirements

Detached ADUs are cozy 16 feet, perfect for bungalows or home offices. The attached options, loftier at 25 feet, offer multi-story flexibility. Junior ADUs, nestled within existing structures, provide studio or guest room solutions and are exempt from specific height restrictions.

Fire Safety Regulations

When building an ADU in Millbrae, ensuring the safety of your occupants is paramount. Fire regulations safeguard lives and property, so understanding these requirements is essential before construction begins.

• Smoke Detectors: All ADUs, regardless of size or type, must be equipped with interconnected smoke detectors on every level, including within bedrooms and hallways. Regular testing and maintenance are vital.
• Escape Routes: Every ADU must have at least two separate escape routes in case of fire, leading directly to the outside or onto an open balcony with safe access to the ground. Windows in bedrooms must be large enough to serve as emergency exits.
• Fire Sprinklers: While not always mandatory, installing fire sprinklers in your ADU adds more protection. This is especially recommended for attached ADUs and units exceeding 750 square feet.
• Fire-Resistant Materials: Certain construction materials, like drywall and insulation, must meet fire-resistant ratings to slow the spread of flames and give occupants time to escape. Consult the building code for specific requirements.
• Gas Appliances: Proper installation and ventilation are crucial if your ADU uses gas appliances for cooking or heating. Regularly maintain these appliances and ensure gas lines are properly sealed and monitored for leaks.

Room Specifications

Parking & Exterior Requirements

Integrating an ADU onto your Millbrae property necessitates careful consideration of both aesthetic and functional aspects. While exterior design guidelines ensure harmonious integration with your neighborhood’s character, parking regulations ensure smooth traffic flow and resident convenience. Detached and attached ADUs exceeding 500 square feet generally require one dedicated off-street parking space, with potential exemptions for specific situations.

Owner-Occupancy

In Millbrae, the owner-occupancy requirement for ADUs adds a unique twist to building considerations. For ADUs permitted between Jan 1, 2020, and Dec 31, 2024, owner-occupancy is not required, allowing you to rent out both your primary dwelling and the ADU for income. However, other regulations like occupancy limits and rental licensing requirements still apply. After Dec 31, 2024, owner-occupancy for new ADUs will resume, requiring either the owner or an immediate family member to occupy the primary dwelling or the ADU.

Rental Requirements

While Millbrae allows renting ADUs and JADUs without owner occupancy until 2025, some key rental requirements exist. ADUs exceeding 500 square feet require school developer fees, and those over 750 square feet face development impact fees based on a percentage of the primary dwelling’s fee. Rental periods must exceed 30 days, and fire sprinkler installation aligns with the primary residence’s requirement.

Millbrae Permits To Acquire and Fees

Embarking on any construction or renovation project in the vibrant city of Millbrae requires navigating a web of permits and associated fees. Whether adding a deck to your cozy bungalow or undertaking a commercial development, understanding the intricacies of the permitting process is essential to ensuring a smooth and compliant journey.

Permit Issuance

The first step in any Millbrae construction endeavor is obtaining a building permit. The permit’s issuance fee varies based on the project’s valuation, with a minimum charge of $50 and reaching potentially higher amounts for larger-scale endeavors. This fee covers the administrative costs of processing your application and ensures your project adheres to safety codes and zoning regulations.

Alongside the primary building permit, additional permits may be required depending on the complexity of your project. This can include electrical, plumbing, and mechanical permits, each with its standards and costs. For an ADU project, special attention should be given to ensuring that all system installations meet current codes for safety and efficiency.

Water and Sewer Connection

Before your blueprints turn into bricks and mortar, they must undergo a meticulous plan review by the City’s Building Division. This comprehensive evaluation ensures your plans comply with building codes, zoning ordinances, and environmental regulations.

The plan review fee is calculated based on the project’s valuation, starting at $100 for small residential projects and escalating for more complex commercial undertakings. A thorough plan review can save you from costly rework and delays.

Electrical and Plumbing Permit

Connecting your project to the city’s water and sewer network necessitates acquiring separate permits from the Public Works Department. The water connection permit fee ranges from $150 to $500, depending on the meter size required. In contrast, the sewer connection permit starts at $200 and adjusts based on factors like flow capacity and distance to existing lines.

When planning for electrical and plumbing work within your project, obtaining the necessary permits is a step that must be considered. For electrical permits, fees are based on the scale of the work, from minor installations to full system rewiring. Plumbing permits are similarly structured; they consider the extent of plumbing work, including installations and repairs to existing structures.

Others: Geological Hazard Review and Clearance, Tree Removal Permit, and Fire Variance.

The safe and efficient functioning of your project’s electrical and plumbing systems demands dedicated permits. The electrical permit fee starts at $50 for minor alterations and scales up according to the project’s amperage requirements and complexity. Similarly, the plumbing permit fee begins at $50 for smaller projects and increases based on the number of fixtures and the scope of work.

Millbrae residents must also navigate specialized permits like the Geological Hazard Review and Clearance, Tree Removal Permit, and Fire Variance. The review for geological hazards is indispensable in areas prone to seismic activity or slope instability, ensuring the safety and integrity of the structures. The associated fees will vary based on the complexity of the assessments required.

Property Designations for Millbrae ADU

To ensure a successful Millbrae Accessory Dwelling Unit (ADU) journey, it is crucial to have a clear understanding of the unique designations that influence your property. These designations encompass environmental and legal factors that can significantly impact the feasibility, design, and construction of your ADU.

• Flood zones: Millbrae has designated areas susceptible to flooding due to storm surges, rivers, or heavy rainfall. Building an ADU in a flood zone might require specific elevation measures or flood insurance, so checking your property’s flood zone status through resources like the Federal Emergency Management Agency (FEMA) Flood Map Service is essential.
• Geohazard zones: Certain areas in Millbrae are prone to geological hazards like landslides, earthquakes, or unstable slopes. Constructing an ADU in a geohazard zone might necessitate additional engineering studies and specialized foundation designs to ensure the unit’s structural integrity.
• Easements: These are legal restrictions granting specific rights to use portions of your property to entities like utility companies or the city. Building an ADU within an easement area might be prohibited or require obtaining permission from the easement holder.

Build Your ADU and Maximize Your Property’s Potential!

Embrace the opportunity to enhance your property’s value and versatility in Millbrae. Constructing an Accessory Dwelling Unit (ADU) with Esperto Builders means partnering with experts who understand the importance of quality, efficiency, and compliance with local guidelines. Contact Esperto Builders today to start your seamless ADU project and take the first step toward unlocking your property’s full potential!

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