Hillsborough ADU Standards
Prefab ADU in Hillsborough
What is an Accessory Dwelling Unit (ADU)?
An ADU is an independent residential unit on the same lot as a primary home, providing additional living space, rental opportunities, or multi-generational housing. A prefab ADU is a permanent, factory-built backyard home that meets local zoning and building codes, making it ideal for long-term living.
Tiny homes, often confused with prefab ADUs, are small, mobile units built on wheels. While both can be ADUs, prefab ADUs are stationary and built to last, whereas tiny homes face more zoning challenges due to their mobility.
Planning to Build an ADU in Hillsborough?
With the implementation of new ADU regulations, Hillsborough has seen an increase in accessory dwelling unit construction. If you’re planning to build an ADU in Hillsborough, LiveLarge is here to guide you through key development requirements for a smooth and successful project.
Types of ADUs
- Detached: A new structure built separately from the primary home.
- Attached: A new unit that is connected to the primary structure.
- Conversion: The transformation of an existing space within a primary residence or a detached accessory structure into an ADU.
- Junior Accessory Dwelling Unit (JADU): A converted space of up to 500 square feet, contained entirely within a single-family residence.
Zoning and Lot Size
All properties zoned for single-family, two-family, or multifamily use may be eligible to build ADUs.
Size and Floor Area
- Attached ADU: 0-1 Bedroom: Maximum 850 sq. ft., 2 Bedrooms: Maximum 1,000 sq. ft., Shall not exceed 50% of the primary residence’s floor area or 1,400 sq. ft., whichever is less.
- Detached ADU: 0-1 Bedroom: Maximum 850 sq. ft., 2 Bedrooms: Maximum 1,000 sq. ft.
- Junior ADU (JADU): Maximum 500 sq. ft.
Setbacks & Height
- Attached ADU: Setbacks: 4-foot side/rear. Height: 16 feet.
- Detached ADU: Setbacks: 4-foot side/rear, 5-foot from the primary home, 25-foot front. Height: 16 feet.
- Conversion of Existing Area: Setbacks: No setbacks are required for the conversion of an existing living area or accessory structure, or for a structure rebuilt in the same location and dimensions as the original.
- Junior ADU (JADU): Setbacks: 4-foot side/rear.
Parking Requirements
- General Requirement:
- One off-street parking space is required per ADU. This space may be provided in setback areas or as tandem parking. However, the town may restrict such configurations in certain areas based on topography, fire safety, or life safety conditions.
- No Parking Required If:
- The ADU is within ½ mile walking distance of public transit.
- The ADU is in an architecturally or historically significant district.
- The ADU is part of the primary residence or an accessory structure.
- On-street parking permits are required but not available to the ADU occupant.
- A car-share vehicle stop is located within one block of the ADU.
- The ADU is part of a new single-family or multifamily dwelling application on the same lot.
- No Replacement Parking Required:
- If a garage, carport, or covered parking structure is demolished or converted into an ADU, the off-street parking spaces do not need to be replaced.
For more information, contact the Hillsborough Planning Division at (650) 348-6660 or via email at adu@hillsborough.net.
LiveLarge Prefab ADUs are designed to meet Hillsborough’s detached ADU regulations, offering a hassle-free way to maximize property value.
With pre-approved designs and expert guidance, we ensure a smooth approval process.
Let LiveLarge be your trusted ADU partner! Our expertise in design, construction, and pre-approved plans ensures your project aligns with local standards and maximizes your property’s potential. Contact us today to start your ADU project!
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