Accessory Dwelling Units (ADU) 

The state of California recognizes accessory dwelling units (ADUs) as an innovative and affordable way to create a more substantial housing supply for California. Now it is easier than ever for people to build an ADU! Legislators approved six laws to reduce barriers for building ADUs. These include allowing ADUs and JADUs to be built concurrently with a single-family dwelling, expanding the allowable zoning districts for ADUs to include all areas that allow single-family and multifamily uses, modifying fees from utilities, and reductions in parking requirements.

As of January 01, 2020, all local ordinances regarding Secondary Dwelling Units are no longer applicable until the ordinances are complicit with current State law. Furthermore, home owner associations (HOAs and CC&Rs) are also limited in their ability to restrict the construction of ADUs. Any governing document is void and unenforceable to the extent that it prohibits, or effectively prohibits, the construction or use of ADUs or junior ADUs

NEW! Fee reductions for ADUs

No impact fees will be assessed for units less than 750 square feet. For a unit that is 750 square feet or more, the impact fees are proportional to the primary unit.

Size of Unit (square feet)Percent of Development Impact Fees Assessed 
749 square feet and below0%
750 - 1,00050%
1,001 and above 100%

The type of permits required to build an ADU can vary. See here for more Building Permit information or to begin your online application process.

What is an ADU?

An ADU is a secondary dwelling (also referred to as granny flats, in-law units, backyard cottages, etc.) that is complete with independent living facilities for one or more persons. There are generally three types:

Attached: The unit is attached to the primary structure

Detached: The unit is separate from the primary structure

Repurposed Existing Space: Space (e.g. master bedroom or garage) within the primary residence that is converted into an individual living space.

What is a JADU? 

Junior Accessory Dwelling Units (JADUs) are a specific type of ADU that is built within an existing residence and shall contain no more than 500 square feet. They may share central systems, contain a basic kitchen utilizing small plug-in appliances, may share a bathroom with the primary dwelling, all to reduce development costs.

ADU Types (Attached, Detached, Conversion examples)

What are the benefits? 

ADUs are a cost-effective type of home that provides independent living space for family members and others. ADUs require no additional land costs, and they do not require any major new infrastructure.  Recent state legislation has significantly reduced or eliminated fees for many ADU’s. This flexible living space can allow seniors to live independently while being close to family, provide an affordable living space for students and young professionals, and help provide supplemental income for the property owner.

Where are ADUs allowed? 

ADUs are allowed in any zone that allows a residential use. A maximum of one ADU and one JADU may be permitted on parcels with a single-family dwelling. On parcels with a multifamily development, the number of ADUs permitted within the footprint of the existing structure may be up to 25 percent of the number of existing units, or one unit, whichever is greater. Up to two detached ADUs may be permitted on a lot with an existing, legal multifamily development.

Grey ADU

Accessory Dwelling Unit Zoning Text Amendments

In response to recent changes in State law, the County Planning Division of the Community Development Resource Agency has prepared a new ordinance, which is expected to be heard by the County Planning Commission and Board of Supervisors in Spring 2020.  

The purpose of the proposed secondary dwelling Zoning Text Amendment is to bring applicable regulations into compliance with recent changes to State law. In preparing its own ordinance the County, per State law, may modify certain State standards but must adhere to others. Based on the new State laws, the County’s current secondary dwelling regulations in the Zoning Ordinance must be amended.  Some of the proposed changes do not apply to the Tahoe Basin because the regulations of secondary dwellings is in part governed by the Tahoe Basin Area Plan and the Tahoe Regional Planning Agency.Wood ADU


Criteria & Design Standards

  1. Size
  2. Parking
  3. Building Permits
  4. Utility Connections

Size

An ADU is intended to be secondary in size to the primary home. An ADU that is attached to a primary dwelling may be up to 50% of the existing unit. An ADU that is detached from the primary home may be up to 1,200 square feet, regardless of the size of the primary structure.            

There is no minimum lot size for an ADU, but adequate water and sewer or septic must be demonstrated.

Second Unit Resource Center (Coming Soon)

Are you interested in building an ADU for your home but are unsure of where to start? Currently, staff are in the process of creating a Second Unit Resource Center to provide information and tools that will make it easier for homeowners to build accessory dwelling units to help increase the housing supply for the County. It willDraft ADU inspiration book include: 

  • An inspiration book for ideas 
  • A step-by-step workbook to guide you in building your unit 
  • A Second Unit Calculator to help estimate the costs, returns, and benefits associated with building an ADU 
  • Dedicated staff to provide assistance at any point in the process 
  • Free pre-approved flexible design plans to save time and reduce development costs

Look out for this addition (COMING SOON!) on the Placer County Housing webpage

If you are interested in having an ADU or JADU built on your property, fill out this form (.doc) and email it to Meghan Schwartz at mschwartz.placer.ca.gov