Portola Valley ADU Standards
Prefab ADU in Portola Valley
What is an ADU (Accessory Dwelling Unit)?
An Accessory Dwelling Unit (ADU) is an independent residential unit located on the same lot as a primary home. ADUs provide 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 considered 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 Portola Valley?
With the implementation of ADU regulations, Portola Valley has seen a rise in accessory dwelling unit construction. If you’re planning to build an ADU in Portola Valley, LiveLarge is here to guide you through key development requirements for a smooth and successful project.
Types of ADUs
- Detached ADU: A newly constructed unit separate from the primary structure.
- Attached ADU: A newly constructed unit attached to the primary residence.
- Conversion ADU: A unit created by converting existing space within a primary residence or a detached accessory structure.
- Junior Accessory Dwelling Unit (JADU): A conversion of existing space, up to 500 sq. ft., entirely within a single-family residence.
Zoning and Lot Size
- Parcels under 3.5 acres: One ADU and one JADU are permitted.
- Parcels 3.5 acres or larger: Two ADUs are allowed—one detached and one internal. A JADU may replace the internal ADU.
- Detached ADUs: Up to 800 sq. ft., 16 ft. in height, and with 4-foot side and rear setbacks are allowed on lots with a single-family dwelling.
- Multi-family lots: Up to two detached ADUs may be built, subject to a 16 ft. height limit and 4-foot side/rear setbacks.
Size and Floor Area
- Attached ADU
- 0-1 Bedroom: Maximum 850 sq. ft.
- 2 Bedrooms: Maximum 1,000 sq. ft.
- Cannot exceed 50% of the primary residence’s floor area.
- Detached ADU
- 0-1 Bedroom: Maximum 850 sq. ft.
- 2 Bedrooms: Maximum 1,000 sq. ft.
- Lots under 3.5 acres: Maximum 1,200 sq. ft.
- Lots over 3.5 acres: Maximum 1,500 sq. ft.
- Junior ADU (JADU)
- Maximum 500 sq. ft.
Setbacks and Height
Attached ADU
- Setbacks: 4 feet (side/rear)
- Height: 16 feet
Detached ADU
- Setbacks:
- 4 feet (side/rear)
- 10 feet from the primary residence
- Front setback:
- 20 feet (for lots <1 acre)
- 50 feet (for lots >1 acre)
- Height: 16 feet
Conversion ADU
- No setbacks required if converting an existing garage or accessory structure.
Junior ADU (JADU)
- Setbacks: 4 feet (side/rear)
Parking Requirements
- JADUs and internal ADUs: No dedicated parking required.
- Detached ADUs: One off-street parking space is required, which may be:
- Covered or uncovered
- In tandem with other parking
- Located in setbacks
- No replacement parking required for the primary residence if:
- A garage is converted into an ADU.
- Existing off-street parking is removed for ADU construction in a single-family district.
- No ADU parking required if the unit is:
- Within ½ mile of public transit.
- In a historic district.
- An interior ADU.
- Ineligible for on-street parking permits (but permits are available nearby).
- Within one block of a car-share vehicle.
For more details, contact the Portola Valley Planning Division at (650) 851-1700 or via email at towncenter@portolavalley.net.
Why Choose LiveLarge Prefab ADUs?
LiveLarge Prefab ADUs are designed to meet Portola Valley’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 partner in your ADU journey! Our expertise in design, construction, and compliance will help you maximize your property’s potential. Contact us today to start your ADU project!
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