Frequently Asked Questions about ADUs


What is an Accessory Dwelling Unit (ADU)?

An ADU is an independent dwelling unit that provides complete living facilities for a household, including permanent provisions for living, sleeping, eating, cooking and sanitation. ADUs can be New Construction or Conversion from existing habitable or non-habitable space. In order to meet this definition, ADUs must have a kitchen with a permanently installed cooking appliance, and a full bath with facilities for sanitation and bathing. Structures without all these facilities are not considered ADUs.

What is a Junior ADU (JADU)?

A JADU is a dwelling unit contained within the walls of a proposed or existing single-family dwelling unit. JADUs may not be more than 500 square feet in size and can include additions to an existing dwelling of no more than 150 square feet. JADUs must include all of the following facilities: independent provisions for living, sleeping, eating, and cooking (area meeting the definition of an efficiency kitchen), and shared or separate sanitation facilities with the main dwelling unit. JADUs are not required to have interior access to the dwelling. Residential areas without all these facilities are not considered JADUs.

What is an Efficiency Kitchen?

An efficiency kitchen is a limited kitchen facility that includes a sink, a refrigerator, small electric kitchen appliances that do not require electrical service greater than 120 volts, an appropriately sized food preparation counter and storage cabinets. Gas or propane cooking appliances are not allowed. Dwelling units may include one efficiency kitchen in addition to a standard kitchen, as long as the efficiency kitchen area has interior access to the rest of the dwelling. If a dwelling includes a JADU, then an additional efficiency kitchen outside the JADU is not allowed.


Can I Build an ADU on My Property?

Use the Eligibility tool on the ADU website to determine your eligibility and the size of ADU you could build on your property. The tool pulls the relevant factors from the County’s GIS database to determine if a parcel meets the requirements of the Santa Cruz County Code (SCCC) to accommodate an ADU. The determination by the eligibility tool can be verified by the County Planning Dept. at (or 454-2130).

How Many ADUs Can I Build on My Property?

The maximum number of ADUs allowed on a single property is based on whether the primary dwelling unit is a single-family home or multifamily (attached) dwelling. Properties with single family homes may have one ADU and one JADU per single family dwelling. Lots with multifamily dwellings may have up to two New Construction detached ADUs plus up to 25% of units can have Conversion ADUs created only from areas that are not currently livable space (such as storage rooms). Learn more at the ADU Overview page.

Some parcels in the County may be large enough relative to their zoning designation to accommodate more than one home as part of a dwelling group, with one ADU and JADU per legal single family dwelling. For example, a 18,000 square foot parcel zoned R-1-6 could either be split into three legal parcels, or three homes could be developed on the existing parcel as part of a dwelling group. If you are interested in learning more about the potential of your property to qualify for a dwelling group, contact the Zoning Counter by emailing or calling 454-2130.

Some parcels may already be developed at or above the maximum density allowed by the zone district and General Plan designation for the parcel. On these "legal non-conforming" parcels, the addition of an ADU or JADU may be considered “intensification” of the nonconforming use and may require a "Level 5 review" (Zoning Administrator public hearing). If you have this situation on your parcel, ask Planning Department staff for help in determining the number of ADUs allowed and the permit process.

Will I Need to Replace Parking if I Convert My Garage?

It depends. Outside the Coastal Zone, garage conversions do not require replacement parking. Inside the Coastal Zone, replacement parking is required. See ADU Overview page for more information about parking requirements.

Is There Any Limit on the Number of ADUs That Can Be Built in the County, or in My Neighborhood Each Year?

No. There is no overall limit on the number of ADUs in the unincorporated County.

Do I Need to Live on the Property?

It depends. On properties with ADUs and JADUs that were permitted before January 1, 2020, the owner is required to live on site. On properties with ADUs permitted during the five-year period from January 1, 2020 through January 1, 2025, owner occupancy is required only if there is also a JADU on the property.

The County requires proof of owner occupancy via a Homeowner’s Tax Exemption filed with the County Assessor or some other official documentation. Property owners have an option to apply for a temporary exception to this owner occupancy requirement at the discretion of the Planning Director.


What Permissions Do I Need in Order to Begin?

Every ADU project will require a building permit. Most ADUs will not require planning permits as long as they comply with the zoning code. Certain ADUs inside the Coastal Zone require Coastal findings that are included in the building permit review. If your parcel is zoned Commercial Agriculture (CA), Timber Production (TP) or Parks and Recreation (PR), a discretionary planning permit is required before a building permit may be issued for an ADU. Some projects may also require additional permits related to grading or any septic system modifications that might be necessary. Your ADU cannot exceed site structural standards without discretionary review – consult with the Zoning Counter at or 454-2130.

How Do I Start the Permit Process?

Review the How-To Guide and other information available on the County’s ADU website: Any additional questions you may have regarding the permit process can be addressed by the Zoning Counter staff at 454-2130 or

Is a Public Hearing or Public Notice Required?

Not normally. In any residential or mixed use zoning district, ADUs that conform to site standards usually require no public hearing or public notice.


Can I Use a ‘Tiny Home’ as an ADU?

Not if the “tiny home” is mobile. To meet building code requirements for habitability, every ADU must be placed on a permanent foundation and connected to utilities (SCCC §13.10.682).ADUs may be conventional construction, pre-fabricated, modular or a mobile home installed on a permanent foundation. The ADU may also be created by converting space in an existing structure. See Types of ADUs page for more information.

Under California law, a tiny home mounted to a chassis with wheels is classified as a Recreational Vehicle (RV), eligible only for occasional or seasonal use and cannot be used as a permanent residence.

Are Any Site Standards Flexible? Can I Reduce Required Setbacks or Build a Taller ADU?

Under certain circumstances, a variance, minor variation or other development permit can provide some flexibility to residential standards:

  • An ADU of up to 800 square feet usually requires only a building permit even if it would exceed the maximum lot coverage or Floor Area Ratio.
  • If you need relief from other site / structural standards, your site may be eligible for a variance or minor exception. Consult SCCC §13.10.230 and § 13.10.235. To confer with a planner, email, call 454-2130 or visit the Zoning Counter (closed Fridays).
  • A discretionary permit with design review can provide for extra height of up to 5 additional feet. The review involves a site visit by staff to ensure that an over-height building will not adversely affect neighborhood or scenic values. The permit is decided by the Zoning Administrator at a public hearing. See SCCC §13.10.323(E)(6)(g) for more detail.
  • For those who might want to build a garage with an ADU above, the County Code allows garages a 50% reduction of side- and rear-yard setbacks. For residential lots less than 10,000 sq.ft. in size, the side and rear setbacks can be reduced to zero with an administrative site development permit (Level IV, which includes notice to neighbors). Details apply, see SCCC §13.10.323(E)(6)(f).

There Is an Accessory Structure on My Property That Was Not Constructed With Permits. Can I Convert It Into an ADU? There Is an ADU That Was Built Without Permits on My Property. Can I Legalize It?

If there is a structure on your property that was built without permits and it is not possible to bring that structure up to current building code standards without demolishing and rebuilding the structure, you may be eligible for the County’s Safe Structures Program. Under this program, a building inspector performs a health and safety inspection and, pending any required health and safety upgrades, a certificate is granted allowing the structure to be used as housing. ADUs are allowed in structures that have completed the Safe Structures program.

If an ADU can be brought up to current building code but the structure does not meet ADU zoning standards such as height or setbacks, building permits can be obtained for the structure as a “legal nonconforming” ADU.

Can I Build the ADU First and a Primary Dwelling Unit Later?

Yes and no! When only one dwelling is constructed on a parcel, it is considered a primary dwelling and standard setbacks and fees apply. However, the initial dwelling can later be “converted” to an ADU, if it meets maximum size and other criteria, and a new primary dwelling can be constructed.

Can I Have an Interior Door Between My Home and an Attached ADU?

The building code allows a connecting door as long as the it meets fire and sound attenuation requirements. Contact the Building Counter for specific information (email


My Property Is on Septic. Am I Allowed to Build an ADU?

Yes, if your septic system can handle the additional flow from the ADU or can be upgraded to do so. Anytime you add bedrooms or convert existing bedrooms to ADUs or JADUs, the septic requirements increase. Applicants should consult with Environmental Health Services (EHS – 454-3234) early in their process regarding the capacity of the existing system and the feasibility of improving it if necessary.

Does My ADU Need a Separate Water Meter or Sewer Connection?

JADUs and Conversion ADUs do not require a new sewer or water connection and no additional capacity charges will be applied. New Construction ADUs may require a separate sewer or water connection. A local agency, special district, or water corporation will determine whether a separate utility connection is required, and the connection fee or capacity charge will be proportionate to the burden of the ADU on the water or sewer system.

What Are the Requirements and Associated Fees of My Water Purveyor/Sanitation District/Fire District? (For Example, Soquel Creek, Water District, San Lorenzo Valley Water District, Central Fire District, Etc.)

Special districts have varying requirements and fees that make construction more expensive in certain neighborhoods. The ADU Fee, Cost and Cash Flow Estimator Tool calculates utility fees charged by Santa Cruz County, but does not calculate fees for all special districts. The ADU Eligibility Tool will identify the special districts that serve your property and provide links to their websites. Contact your district directly to find out the requirements and costs of building or legalizing an ADU.

Do I Need to Install Fire Sprinklers in My ADU?

Fire sprinklers are generally required in an ADU only if they are present or being installed in the primary home on the parcel. However, you will still need approval from the appropriate fire district and will need to comply with the fire code. Per fire code, sprinklers are required for projects involving an addition totaling more than 50% of the primary dwelling square footage. This means that sprinklers may be required if your project involves an attached ADU exceeding 50% of the primary dwelling square footage on its own or when combined with other concurrent additions to the primary dwelling. Also, a fire district may require extra on-site water storage for an ADU that is not sprinklered. In this circumstance, installing sprinklers in the ADU may be the most cost-effective option for meeting fire code requirements.


How Much Will It Cost to Build an ADU?

Your costs will vary with the type of unit – are you converting part of your existing home or building a new cottage in the back yard? Are you building a JADU or standard ADU? Are you building a garage at the same time? Are you utilizing aa mobile home, modular unit or kit-construction? You can use the ADU Fee, Cost and Cash Flow Estimator Tool and review the Plan Your Financing page to learn more about estimated costs and financing options for your ADU.

Will My Property Taxes Increase?

Constructing and ADU will incrementally increase the value of your property, and the tax on that amount of increase is added to the tax that was assessed before the improvement. However, the base value of the property is not reassessed, and any tax advantages that exist, for example, from longtime ownership with no reassessment, will not be affected. Property Tax implications are discussed in greater detail in Section 7 of the ADU Financing Guide.


I Would Like to Rent My ADU. What Do I Need to Know to Become a Landlord?

Section 8 of the ADU Financing Guide contains a list of resources for a successful renting experience including guidance about creating a lease, tips on selecting tenants, information to help you understand your legal responsibilities and guidance on maintaining a rental unit. Helpful links are also available in the Landlord section of our Resources page.

Can I Rent My ADU as a Vacation Rental or Other Short-Term Basis?

No. An ADU cannot be used as any type of short-term rental, and an ADU cannot be located on a property with an active Vacation Rental or Hosted Rental permit. Any existing Vacation Rental or Hosted Rental permit must be forfeited before a permit can be issued to construct an ADU.