Each of these seven homes is an example of an accessory dwelling unit or ADU

If you are planning to build an ADU there are a few items you will be considering before embarking on your project. The State at large and the County of Santa Cruz in particular have a recognized housing shortage and, over the past several years, Sacramento has passed successive rounds of legislation geared towards alleviating that shortage by making the regulatory environment more ADU-friendly. With new legislation emerging on what seems like a monthly basis, ADU rules are truly a moving target – in this article we present an overview of the County’s regulatory framework for ADUs current as of this writing. Note that each local jurisdiction in the Monterey Bay area – Cities of Santa Cruz, Capitola, Watsonville, and Scotts Valley – each have their own, specific regulations: this article applies specifically to ADU regulations particular to the unincorporated areas of Santa Cruz County.

County of Santa Cruz ADU Overview
Santa Cruz County defines accessory Dwelling Units (ADUs) as secondary housing units that can be attached or detached accessory structures associated with single or multifamily dwellings. Although the unit cannot be purchased or sold independently, it is frequently used to house a relative or to generate supplemental income as rental housing.

Overview of ADU Regulations
Accessory dwelling units (ADUs) are allowed on any parcel where the zoning district or General Plan allows residential uses, and there is an existing or proposed primary dwelling. ADUs can be attached or detached from the primary dwelling, new construction or converted from existing space, and can be standard or junior ADUs. For more information see Types of ADUs.

Conversion ADUs: Legality of Existing Structure
If the ADU involves an existing structure e.g., interior conversions, garage conversion – only those constructed legally (i.e. with permits) may be converted to ADUs. Illegal structures converted to ADUs will be treated as new construction projects, with associated requirements. Property owners seeking to legalize ADUs already constructed without permits or within structures built without permits may opt to obtain certification through the County’s Safe Structures Program (formerly known as Limited Immunity Amnesty Program).

Permits Necessary
Most ADUs require only a building permit, using the County’s online ePlan review process. ADU building permit applications are reviewed within 60 days of submittal. Additional review may be imposed during building permit processing for ADUs proposed in the Coastal Zone jurisdiction or for those involving modifications to an existing non-conforming dwelling.

Wastewater Regulations
For properties on the public sewer system, the ADU’s additional effluent may trigger an increase in the size of the sewer lateral to the house. For those relying instead on individual septic systems, a septic system upgrade will result if the additional demand of the ADU exceeds the capacity of the existing system. Because either of these outcomes constitute big ticket items, a face-to-face meeting with County Environmental Health should be on the checklist of anyone contemplating a new or conversion ADU.

ADUs as Rental Income
Previously, California state law (and thus, County ordinance) precluded ADUs as rental units, restricting their use to only family members. However, under the new regime and resulting mandates long term rentals are now entirely legal. Short-term leases (rentals of less than 30 days), however, are not allowed on properties with ADUs. Consequently, homes with ADUs are ineligible for the County’s hosted or vacation rental programs.

Number of ADUs Allowed
Parcels with single-family dwellings: A maximum of one ADU and one JADU are permitted on parcels with single-family homes. The multifamily building rule may apply if both an ADU and JADU are planned to be attached to a single-family home.
Parcels with multifamily dwellings: Two detached ADUs, which may be connected to one another, are permitted on a multi-family property, and up to 25% of the units may have an ADU created out of previously unusable space, such as a garage or storage area.

ADU Size Limitations
JADU: Minimum 150 sf, maximum 500 sf.
Conversion ADUs: Minimum 150 sf, no maximum size.
New Construction ADU: Minimum 150 sf up to a maximum of 1,200 sf based on parcel size
Use the County’s Allowable ADU Size and Special Districts online tool to assess your parcel’s eligibility and size limits for your prospective ADU.

Parking Requirements
Parking is not required for Conversion ADUs or JADUs: property owners converting garages to ADUs do not need to replace lost parking spaces except in certain coastal areas.
New Construction ADUs: require one new parking space, except in the following locations when outside certain coastal areas:
• Historic districts
• Within one block of designated car share parking
• Within ½ mile walking distance of any transit stop (except in designated coastal areas)
Coastal Parking Regulations: within the Live Oak Designated Area, Seacliff/Aptos/La Selva Designated Area, Davenport/Swanton Designated Area, and Opal Cliff Drive between 41st Ave and the City of Capitola, one parking space is required for new construction ADUs, with no exceptions, and replacement parking is required when existing parking is demolished or converted for construction of an ADU.

Building Envelope
New construction ADUs have special setbacks and height standards that define the building envelope for these structures. See the Planning Department’s Building Envelope link to review these in detail as they pertain to your parcel’s size and location.

Permit Costs, Fees, and Waivers
Permitting, planning and other fees vary with ADU type and parcel location. To the extent fees are based on size of the unit, number of bedrooms or project valuation, ADU design is a strong determinate of permit fee costs. See the County’s Fee, Cost and Cash Flow Estimator as one means towards gathering this information. Certain fees are waived or reduced for ADUs as follows:
• reduced building permit fees for Conversion ADUs.
• waiver of sewer and water connection fees for JADUs and Conversion ADUs.
• waiver of Planning Department permit fees for ADUs ≤ 640 sf.
• waiver of impact fees for ADUs less than 750 sf. Impact fees for larger ADUs are proportional to square footage.
• waiver of transportation and roads fees when no parking is required for ADU.
• waiver of Affordable Housing Impact fee for Conversion ADUs.