Woodside ADU Zoning and Building Standards

California’s new ADU laws present exciting opportunities for homeowners in Woodside. Adding an Accessory Dwelling Unit (ADU) can unlock hidden value and transform your space. Before you begin, familiarize yourself with Woodside special use regulations for these versatile additions. Understanding these guidelines will ensure a smooth and successful ADU journey, maximizing your investment and bringing your vision to life.

Woodside ADU Zoning and Building Standards

Property Requirements

  • Single-Family Zoned Lots:

Quaint bungalows, charming cottages, and spacious homes characterize Woodside single-family zoned lots. The great advantage is that there is no minimum lot size requirement for building ADUs on these properties. The ADU can be constructed regardless of lot size if it complies with setbacks and height restrictions.

  • Duplex Family Zoned Lots:

Picture charming duplexes with shared walls and separate entrances – these are the essence of Woodside duplex family-zoned lots. Here, the building size limitations for ADUs are based on your existing main residence’s total floor area (TFA).

  • If your main residence is under 4,000 sq. ft.: The maximum TFA for your ADU is 18% of your lot area. For example, if your lot is 10,000 sq. ft., the largest ADU you could build would be 1,800 sq. ft.
  • If your main residence is 4,000 sq. ft. or more: There’s a formula to determine the maximum TFA for your ADU, which considers the size of your main residence and lot. You can find the formula on the Town of Woodside website.
  • Multi-Family Zoned Lots:

Think apartment buildings and townhomes – these are the bustling hubs of Woodside multi-family zoned lots. Here, the building size limitations for ADUs are slightly different than in other zones.

  • Attached ADUs: These are connected to the main residence and can be up to 50% of the size of the existing main residence, with a maximum of 1,200 sq. ft.
  • Detached ADUs: These stand alone from the main residence and can be up to 25% of the size of the existing main residence, with a maximum of 750 sq. ft.


Woodside ADUs require owner-occupancy, meaning the owner of the property must live in either the main house or the ADU. This helps ensure ADUs contribute to the community and prevent them from becoming solely rental units. A few exceptions exist, such as when the property is owned by a land trust or housing organization promoting affordable housing.

Number of Units Allowed

Woodside allows you to build up to two ADUs on your property, depending on its size and zoning. For most single-family lots, you can have one attached or one detached ADU, while larger parcels can accommodate two attached or detached units.

Woodside Building Height

  • Single-family: your ADU’s maximum height is generally 16 feet for attached units and 18 feet for detached ones.
  • Duplex family: In these zones, attached ADUs follow the same 18-foot height limit, while detached units can reach a loftier 20 feet. Duplex ADUs can offer flexible living spaces or even two-story rentals.
  • Multi-family: For attached ADUs, the height bar stays 18 feet, while detached units can stretch up to 22 feet. These multi-family ADUs can be perfect for larger families or income-generating rentals.

Woodside Building Size

  • Single-Family Freedom: No minimum lot size requirement here! You can build an ADU of any size if it follows setback and height restrictions. Think cozy studio or spacious multi-bedroom unit – the choice is yours.
  • Duplex Dance: ADU size depends on your main house’s footprint. If under 4,000 sq. ft., your ADU can be up to 18% of your lot area; think of efficient layouts like studio apartments or one-bedroom havens. Bigger main houses unlock larger ADU possibilities, with formulas to determine the exact size.
  • Multi-Family Mix: Attached ADUs can be half the size of your main house, maxing out at 1,200 sq. ft. Picture townhouse-style units. Detached ADUs get 25% of your main house’s size, with a 750 sq. ft. cap, ideal for compact yet comfortable living spaces.

Fire Safety Regulations

Fire safety is paramount in Woodside ADUs! Expect requirements like smoke detectors, sprinkler systems in some cases, and specific setbacks from main structures and property lines to ensure everyone’s safety in case of a fire. Remember, these regulations protect life, so prioritize them when planning your ADU!


Woodside ADUs generally require one parking space for attached and detached units unless you qualify for an exemption (like proximity to transit or senior housing).

Utility Connections

In most cases, you won’t need separate connections for your ADU. Simply tap into existing lines serving your main residence for water, sewer, and electricity. Think of it as sharing resources efficiently!

For larger ADUs exceeding size thresholds or located far from existing lines, separate connections may be necessary. But don’t worry! The Town of Woodside permitting process provides a guide through every step, ensuring your ADU has all the essential utilities.


Accessory Dwelling Units (ADUs) typically require a 4-foot buffer from side and rear property lines, allowing space for amenities and green surroundings. Front setbacks vary based on zoning, ensuring well-maintained lawns or entryways. Exceptions exist for ADUs like conversions or junior units, where larger setbacks may be necessary for fire safety.

Zoning Regulations

Woodside ADU Zoning Regulations

Single Family

No minimum lot size is required, so you can add an ADU if you have a cozy cottage or a spacious estate. Remember to follow the general building size, height, and setback guidelines to ensure your new unit blends harmoniously with the neighborhood.

Duplex Family

The size of your ADU depends on the size of your main residence. If your main house is under 4,000 sq. ft., your ADU can be up to 18% of your lot area. The ADU size scales up for larger main houses, allowing for more spacious options like two-bedroom or rental apartments.


Attached ADUs can be up to half the size of your main house, maxing out at 1,200 sq. ft. Detached ADUs get 25% of your main house’s size, with a 750 sq. ft. cap, ideal for compact yet comfortable living spaces like studios or one-bedroom havens.

RF Zone Minimum Lot Area in San Leandro

In Woodside 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.

  • RF-20: 20,000 sq. ft. This is the smallest lot size allowed in the RF Zone and is typically used for single-family homes.
  • RF-30: 30,000 sq. ft. This larger lot is often used for larger homes, such as two-story homes or homes with attached garages.
  • RF-40: 40,000 sq. ft. This is the largest lot size allowed in the RF Zone and is typically used for estate homes or horse ranches.

Room Specifications

Woodside ADU Room Specifications

Room Type Specifications
Bathroom – Minimum floor area: 35 sq. ft. (excluding the toilet closet) for full bathrooms, 20 sq. ft. for half bathrooms

– Toilet, sink, and shower/tub or shower stall required.

– Toilet closet must be at least 30″ x 60″.

– Minimum ceiling height: 7 ft.

Kitchen  Minimum floor area: 40 sq. ft. for kitchenettes, 60 sq. ft. for full kitchens.

– Sink, countertop, and cooking appliances (microwave or range top) required.

– Refrigerator required for full kitchens (size varies by number of bedrooms).

– Minimum countertop length: 48″ for kitchenettes, 60″ for full kitchens.

– Minimum ceiling height: 7 ft.

Sleeping Areas  Minimum floor area: 70 sq. ft. for bedrooms with single bed, 80 sq. ft. for double bed, 100 sq. ft. for queen or king bed.

– Closet required (minimum size varies by local regulations)

– Window with a minimum area of 5 sq. ft. required

– Minimum ceiling height: 7 ft.

Storage – At least 5% of the total ADU floor area dedicated to storage (e.g., closet space, built-in cabinets)

– Consider additional options like attic or crawl space

access if permitted.

Woodside Requirements

Detached ADU Woodside: Freestanding unit offering privacy and independence. Typically has its entrance and utilities. Requires larger lot size and may have specific setback regulations. Ideal for multi-generational living or rental income.

Attached ADU Woodside: Connects directly to the main residence. Shares some walls and utilities, potentially lowering construction costs. It may impact the design and layout of the main house. Good option for guest space, home office, or expanding living area.

JADU Woodside: Small unit (usually under 500 sq. ft.) often located within an existing structure like a garage or basement. Shares bathroom and utilities with the main house. It has limited size and function but is perfect for a home office, guest room, or temporary living space.

Rental Requirements

  • Proof of income: Typically, landlords require documentation showing you earn at least 2-3 times the monthly rent.
  • Credit score: Many landlords look for renters with good credit scores (often above 650-700).
  • Rental history: Positive references from previous landlords are often requested.
  • Application fee: Most landlords charge an application fee, typically $30-$50, to cover background checks and credit reports.
  • Security deposit: Typically equals one month’s rent, which covers any damages or unpaid rent.
  • Proof of renter’s insurance: Most landlords require renters to obtain liability insurance.
  • Pet policy: Some landlords allow pets but may have size, breed, and number restrictions. Pet fees might also apply.
  • Smoking policy: Many landlords have smoke-free policies in their rental units.

Development Standards for Woodside ADU

ADU Types Development Standards Specifications
Single-family – No minimum lot size requirement

– Maximum TFA: 10% of lot area + 1,000 sq. ft. (up to 3,000 sq. ft.)

– Minimum setbacks: 4 ft. from sides and rear

– Attached or detached allowed

Duplex  – Maximum TFA depends on main house size:

– Under 4,000 sq. ft. main house: 18% of lot area

– Over 4,000 sq. ft. main house: see formula on Town website

– Minimum setbacks: 4 ft. from sides and rear

– Attached or detached allowed

Multi-family Attached ADU:

– Up to 50% of the main house size (max 1,200 sq. ft.)

– Minimum setbacks: 4 ft. from sides and rear

Detached ADU:

– Up to 25% of the main house size (max 750 sq. ft.)

– Minimum setbacks: 4 ft. from sides and rear

– Attached or detached allowed depending on lot size

Junior ADUs (JADUs) – Converted space within existing structure (garage, basement)

– No minimum lot size requirement

– Maximum TFA: 500 sq. ft.

– Must share bathroom and utilities with the main house

– Minimum setbacks depend on location within an existing structure

Woodside Property Designations for ADU

  • Flood zones: Flood zones determine the likelihood of property flooding. Check your property’s zone to see if any building restrictions apply to your ADU. High-risk zones may require elevated foundations or special materials.
  • Geohazard zones: Building your ADU in a designated zone might necessitate additional safety measures like seismic reinforcements or slope stabilization.
  • Easements: provide access to certain areas of your property for utilities, roads, or other purposes. Be sure to check for easements before proceeding with your ADU plans. Blocking or building on an easement can cause delays and legal issues.

ADU Permit Requirements and Fees

Woodside ADU Permit Requirements and Fees

  • Building Permit: Mandatory for all ADU construction, including plans, inspections, and approvals. Cost varies based on project size and complexity, typically around $1,000.
  • Electrical Permit: Ensures safe electrical wiring and installations. Cost varies depending on project scope, typically around $150-$300.
  • Plumbing Permit: Guarantees proper plumbing installation and compliance with codes. Cost varies based on project size, typically around $150-$300.
  • Other Permits: Additional permits for specific aspects like fire sprinklers, gas lines, or demolition may be required.

Design Your Dream ADU Today!

Craft your perfect ADU with our expertise. Whether it’s an extra living space, a rental opportunity, or a home office, our team of architects and builders will bring your vision to life. Contact us today at +1-669-293-1126 to start planning your dream ADU. Let’s transform your space and create an ADU that embodies your style and aspirations.


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.

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