What permits are required for a garage conversion in California?

A California garage conversion is permitted as the creation of a legal dwelling, so it requires a building permit and the associated trade scopes — mechanical, electrical, and plumbing — plus a registered Title 24 energy document. Some cities review all of this under a single combination building permit; others issue separate M, E, and P trade permits. The exact structure varies by jurisdiction, so confirm with your local building department.

The permits and documents involved

• Building permit (ADU) — the master permit covering the conversion of non-habitable space into a dwelling, including framing the door opening, insulation, egress, and habitability.
• Mechanical scope — for the new HVAC and ASHRAE 62.2 ventilation, reviewed under the building permit or as a separate trade permit.
• Electrical scope — for the new subpanel, circuits, and load calculation; a service or panel upgrade may also require utility coordination separate from the permit.
• Plumbing scope — for the new kitchen and bathroom water-supply and DWV system and the sewer tie-in.
• Registered Title 24 CF1R — the energy compliance certificate on the alteration pathway, submitted with the application.

What the submittal package contains

To clear the completeness review and enter plan check, a typical garage-conversion submittal includes:

• Architectural plans — floor plan, site plan, and elevations showing the closed door opening, egress, and finished layout
• Structural details where the opening framing, slab, or roof is altered
• Coordinated mechanical, electrical, and plumbing plans
• The registered CF1R
• City-specific application forms and fees

Fees and approvals beyond the building permit

A garage conversion can also involve school fees (above a size threshold), sewer-capacity or water-connection fees from your district, and utility coordination for any service upgrade. ADUs are exempt from many impact fees under state law, but local fees vary — confirm with your building department and water/sewer provider.

Note that MEP plans cover the active engineered systems; the architectural and structural sheets are prepared by your designer or architect. Knowing that split up front helps you assemble a complete package rather than discovering a missing sheet mid-review.

One permit, several review tracks

Whether your city bundles the trades or splits them, the underlying review work is the same: a plan checker examines the architectural and structural drawings for habitability and life safety, while the MEP scope is checked for code-compliant circuits and loads, DWV venting and slope, HVAC sizing and ventilation, and energy compliance. Cities that issue separate trade permits will often want each discipline's sheet stamped and submitted with its own application, so it helps to know your jurisdiction's structure before you file. The plan set we produce is built to drop into either model.

Requirements vary by jurisdiction — confirm the exact permit and submittal list with your local building department. Our coordinated MEP plans plus an optional registered Title 24 give you the engineered sheets the permit requires; see the California ADU permit guide or start your order.