Frequently Asked Questions about ADUs

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 zoning code to accommodate an ADU. The determination by the eligibility tool is preliminary and can be verified by contacting the Zoning Counter at or calling 454-2130.

How much will it cost me to build an ADU?

Your costs will vary based on how you choose to create the unit (are you converting part of your existing home, or building a new cottage in the back yard? Are you building a garage at the same time? Are you utilizing a pre-fab structure or manufactured home?, and where you are located in the County? The ADU Financing Guide provides extensive guidance on the various options for developing an ADU on your property.

What features and facilities are ADUs required to have?

An ADU is an independent dwelling unit providing complete living facilities for a household, including permanent provisions for living, sleeping, eating, cooking and sanitation. In order to meet this definition, ADUs must have a full kitchen, including a permanently installed cooking appliance, and a full bath with facilities for sanitation and bathing. Structures without all these facilities are not legal dwelling units.

Can I use a Tiny Home as an ADU?

Any structure that meets building code requirements for habitability, when placed on a permanent foundation and connected to utilities (County Code Section13.1.0682), is eligible for building permits and can be used as an ADU. A small “Tiny ADU” may be “stick-built” construction, a pre-fabricated unit brought to the site and installed (similar to a manufactured home that meets the HUD building standard), or may be created from converting space in an existing structure.

Many “tiny homes” are mounted to a wheeled chassis to facilitate moving them from place to place. Under California state housing law, anything that is permanently mounted to a chassis with wheels is a Recreational Vehicle (RV) approved only for occasional and seasonal use and cannot be used as a dwelling .

What permissions do I need in order to begin building/remodeling? 

Every ADU project will require a building permit, and most ADUs will not require other permits so long as they comply with the zoning code. Certain ADUs inside the Coastal Zone will require a Coastal Development Permit, processed at the same time as the building permit application. If your parcel is zoned Commercial Agriculture (CA), you must obtain approval of a discretionary land use development permit from the County, which involves public notice to your neighbors, before you can apply for a building permit for an ADU. Some projects may also require additional permits related to grading or any septic system modifications that might be necessary. If you are designing an ADU that exceeds any of the site or dimensional standards, you also may need a discretionary development permit – consult with the Zoning Counter at or 454-2130.

How do I start the permit process?

Consult the How-To Guide, and review the other information available on this website. Any questions you may have regarding the permit process can be addressed by the zoning counter staff. To contact zoning staff, you may either call the Zoning Information line at 454-2130 and leave a message with your questions or send an email to with “ADU” in the subject line.  

Will there be a public hearing, and do I need to inform my neighbors about my plans for an ADU? 

For the most part, no. When the plans for your ADU conform to the normal standards set in the County Code and your project doesn’t trigger the need for any permit other than a building permit, there is no public hearing or notice given to neighbor parcels.

If your parcel is located in certain areas inside the Coastal Zone, and your ADU does not qualify to be exempt or excluded from the County’s Coastal Permit regulations, your ADU may also require a Coastal Development Permit (CDP) which will involve noticing to your neighbors. The CDP is processed simultaneously with your Building Permit application, and typically will not cause any delay in your project. If your parcel is zoned Commercial Agriculture (CA), you must obtain approval of a development permit from the County, which involves public notice to your neighbors, before you can apply for a building permit for an ADU.

Are any of the site standards flexible? Can I reduce my required setbacks or build a taller ADU?

If the design of your ADU does not conform to the normal zoning standards, a development permit, variance, or minor variation process can allow you the flexibility your project will require:

  • A development permit for design review can provide for extra height of up to 5 additional feet. This involves a site visit by staff to ensure that an over-height building will not create excessive impacts on neighboring properties or on public coastal views (if property is inside the Coastal Zone). The findings of the review will be formalized in a public hearing before the Zoning Administrator. See Code Section 13.10.323(E)6(g) for more detail.
  • ADUs built above a garage might benefit from flexibility in site planning with reduced setbacks. The County Code allows a setback reduction of up to 50% of the standard side- and rear-yard setbacks without the need for a special permit. For residential lots less than 10,000 sf in size, the setback can be reduced to zero with an administrative site development permit (Level IV, which includes notice to neighbors). Details apply, see County Code Section 13.10.323(E)6(f).
  • If your planned ADU does not conform to any other site or structural standard, such as lot coverage or floor area ratio, you may be eligible to apply for a variance or minor exception. Consult with a planner at the Zoning Counter ( or 454-2130) for more information, and see County Code Sections 13.10.230 and 13.10.235

Is there any limit on the number of ADUs that can be built in the County, or in my neighborhood each year?

No. There are no limits on the number of permits that can be issued for ADUs in the unincorporated County, other than that only one ADU can be built per parcel in conjunction with a new or existing Single Family home.

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. Applicants should consult with Environmental Health Services (EHS) early in their process. The zoning code allows development of ADUs on any parcel with a single family home, regardless of size and regardless of the use of a septic system, as long as all performance standards for sanitation must be met and approved by EHS. The technical requirements for septic systems on certain parcels may be challenging or prohibitively expensive in some cases.  EHS staff can provide advice about evaluating your existing system help you understand the requirements to upgrade if necessary.

Does my ADU need a separate water meter or sewer connection?

Conversion ADUs cannot be required to have a separate water or sewer connection. The requirements for New Construction ADUs vary from one district to another. The GIS tool on the ADU website at will identify the Special Districts that serve your property and provide you with links to their websites. Once you know your special districts, we recommend contacting the Districts directly to discuss the requirements and costs of building or legalizing an ADU on your parcel, since each district has their own standards and requirements.

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 GIS tool on the ADU website at will identify the Special Districts that serve your property and provide you with links to their websites. Once you know your special districts, we recommend contacting the Districts directly to discuss the requirements and costs of building or legalizing an ADU on your parcel, since each district has their own standards and requirements.

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?

Maybe. Your first step will be to contact the Zoning Information line at 454-2130 or send an email to line to find out what standards will apply to the  structure and its location on your parcel. There is no risk in asking these questions, as the County Code enforcement process operates solely on a complaint basis unless there is an imminent risk to health and safety.

Do I need to install fire sprinklers in my ADU?

Fire sprinklers are only required in an ADU if they are already present or are being installed in the primary home on the parcel. Regardless of whether or not sprinklers are required, ADU projects must be approved by the appropriate fire district, and will need to comply with the Fire Code generally. There may be circumstances in which installing sprinklers is the most cost effective option for meeting the requirements of the Fire Code. For instance, buildings that are not sprinklered require extra water storage on site, which may be more expensive than sprinkler installation depending on the site conditions.

Do I need to live on the property?

Yes. At the time of application for a new or legalized ADU, the County will confirm that you have filed a Homeowner’s Tax exemption or can otherwise prove the property is your primary residence. Once an ADU is in place, there is a process to apply for a one-year exception to allow rental of both units for qualifying reasons at the discretion of the Planning Director.

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 understandyour legal responsibilities, as well as guidance on maintaining a rental unit. Some 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 or vacation rental, and an ADU cannot be located on a property with an active Vacation Rental Permit. Any existing Vacation Rental Permit must be forfeited before a permit can be issued to construct an ADU.

Can I build two ADUs?

No. Only one ADU is permitted per qualified parcel.

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. 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.

Can I have an interior door between my home and an attached ADU?

The current building code standards can allow a door directly between two dwelling units. The door will be subject to higher standards by the Building code in order to meet fire and sound attenuation requirements, but you can have a door connecting your home and your ADU. Contact the Building Counter for specific information on the standards that will apply (email or call 831-454-2260 during regular business hours).

Will my Property Taxes increase?

Yes, slightly. 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