Planning a Detached ADU in California
Thinking about a standalone backyard ADU? Here's what planning and permitting a detached ADU generally involves, from site placement to plans and permits.
What Is a Detached ADU?
A detached ADU — sometimes called a backyard ADU — is a standalone accessory dwelling unit, separate from the main house, often placed in a backyard or side yard. Because it's an independent structure, a detached ADU typically involves its own foundation and utility connections, in addition to the design and permitting steps common to any new ADU.
Legal ADU Pro helps California homeowners understand what planning a detached backyard ADU typically involves and coordinate the plans, documentation, and professionals a project needs.
Site & Placement Considerations
- Placement on the lot and setbacks from property lines
- Access to water, sewer, and electrical utility connections
- Lot coverage and any applicable size limits
- Access and parking requirements, where they apply
These specifics vary by city and county — an individual review of your property is needed to understand what applies to your situation.
General Process Overview
While every project and jurisdiction is different, planning a detached ADU generally involves: an initial review of the property and site, coordinating a site plan and floor plan, submitting for the appropriate permits, responding to any plan check corrections, and completing inspections during and after construction.
Because a detached ADU is a new, freestanding structure, plans typically need to address foundation, structural, and utility connection details in more depth than a conversion of existing space.
Plan Your Detached ADU
Legal ADU Pro can help you understand what a detached ADU project on your property typically involves.
Request a Property Review →Explore planning options for attached, garage conversion, and other new ADU projects.
View New ADU Services →Once plans are underway, see what's involved in coordinating permit submittal for a new ADU.
ADU Permit Coordination →If the structure already exists and wasn't permitted, this isn't the right page — see Detached Structure Legalization instead.
Detached Structure Legalization →What a Detached ADU Typically Needs
Most detached ADU projects need some combination of a site plan, floor plan, and elevations before they can be submitted for permits — see our ADU plans, drafting & design coordination guide for what's typically involved and when a licensed professional is required.
Questions About Planning a Detached ADU
In many cases, yes — a detached, backyard ADU is one of the most common types of new ADU in California. Whether your specific backyard can accommodate one depends on lot size, setbacks, and access to utilities. See our New ADU Feasibility Review to understand what's realistic for your property.
They generally describe the same thing — a detached, backyard ADU is a standalone unit separate from the main house, most often placed in a backyard or side yard.
Not necessarily. Feasibility depends on lot size, setbacks, existing structures, and the requirements of the reviewing jurisdiction. An individual review is needed to understand what's realistic for your specific property. See our New ADU Feasibility Review for more.
Often, yes, depending on the scope of the project and the requirements of the reviewing jurisdiction. Legal ADU Pro helps identify when licensed professionals are likely needed and can help coordinate with them.
Ready to Plan Your Detached ADU?
Request an initial property review and understand what planning a detached ADU on your property typically involves.
Request a Property Review → Call 310-570-2885