The Different Types of ADUs: A Guide for Santa Clara County Homeowners

As housing demand continues to rise in Santa Clara County, homeowners are increasingly turning to Accessory Dwelling Units (ADUs) as a smart solution for adding extra living space and increasing property value. But did you know that there are several different types of ADUs? Understanding your options can help you determine the best fit for your property and investment goals.

What is an ADU?

An Accessory Dwelling Unit (ADU) is a self-contained residential unit located on the same lot as a single-family or multi-family home. ADUs are commonly used as rental units, guest houses, or in-law suites, and they provide an excellent way to increase housing availability in Santa Clara County.

Types of ADUs in Santa Clara County

1. Detached ADUs (Backyard Cottages)

A Detached ADU is a stand-alone structure separate from the main house. These units offer maximum privacy and flexibility for homeowners looking to rent out space or create an independent living area for family members.

Benefits of Detached ADUs:

• Increased privacy for tenants and homeowners

• Potential for higher rental income

• More design flexibility and customization

Zoning Considerations in Santa Clara County: Detached ADUs are typically allowed in residential zones, but size limits and setback requirements vary by city. Most jurisdictions in Santa Clara County permit up to 1,200 square feet for a detached ADU, depending on lot size.

2. Attached ADUs

An Attached ADU shares at least one wall with the main house but has a separate entrance. These are ideal for homeowners who want additional living space without the cost of constructing a completely new structure.

Benefits of Attached ADUs:

• More affordable than detached ADUs

• Easier to integrate utilities with the main house

• Can increase property value without taking up backyard space

Santa Clara County Regulations: Attached ADUs generally cannot exceed 50% of the main home’s square footage, with a maximum of 1,200 square feet in most cases.

3. Garage Conversion ADUs

A Garage Conversion ADU involves transforming an existing garage into a livable unit. This is one of the most cost-effective ways to build an ADU, as it utilizes existing structures.

Benefits of Garage Conversions:

• Lower construction costs

• Faster permitting process

• Ideal for small rental units or home offices

Local Considerations: Santa Clara County requires that converted garages meet habitability standards, including proper insulation, ventilation, and fire safety features. Parking replacement may be required unless the home is within half a mile of public transit.

4. Junior ADUs (Carve Out)

A Junior ADU (Carve Out) is a smaller, more compact unit—usually no larger than 500 square feet—that is converted from an existing space within the primary home, such as a bedroom or garage. Unlike standard ADUs, JADUs can share bathroom facilities with the main house.

Benefits of Carve Out ADUs:

• Extremely cost-effective

• Requires fewer zoning restrictions

• Ideal for housing family members or short-term rentals

Key Requirements in Santa Clara County:

• Must be built within the existing footprint of the home

• Requires an efficiency kitchen but may share a bathroom with the main home

• The homeowner must live on the property when a JADU is added

Choosing the Right ADU for Your Santa Clara County Property

When deciding which type of ADU to build, consider the following:

• Budget: Detached ADUs tend to be the most expensive, while JADUs and garage conversions are more affordable.

• Available Space: Larger lots may accommodate detached ADUs, while smaller properties might benefit from attached or basement ADUs.

• Intended Use: Are you looking for rental income, multigenerational living, or a home office? Your purpose will influence the best ADU type.

• Local Regulations: Every city in Santa Clara County has its own ADU regulations, we will help you work with your local planning department before proceeding.

   

Need Help with Your ADU Project?

If you’re considering building an ADU in San Jose, Sunnyvale, Campbell, or anywhere in Santa Clara County, we are here to help. Contact us today to get expert guidance on making your ADU dream a reality!