What does the inspector check at an ADU rough-in inspection?

At rough-in, the inspector looks at the plumbing, electrical and mechanical work inside open walls and ceilings and compares it with your approved plans and the code before anything is covered. Los Angeles's homeowner guide describes the rough stage as uncovered framing with plumbing, electrical wiring and ducts installed. San Diego states that all construction requiring a permit must be inspected before it is covered or concealed.

Where rough-in fits

LA's guide lists groundwork (underground plumbing and electrical before concrete), rough, insulation, drywall and final, followed by a certificate of occupancy for new buildings, additions and conversions. Names and order vary by city. In San Diego, the inspection record card lists the inspection types for your permit.

What is commonly checked at rough

• Plumbing. Drain, waste and vent pipe sizes, slope and venting; water supply piping and materials; gas piping if any; and the tests the California Plumbing Code requires on piping before it is concealed.
• Electrical. The panel or subpanel and feeder, circuit routing, box locations compared with the plan, and how cables are supported and protected where they pass through framing. San Diego notes that panels and junction boxes must be accessible and that inspectors will not open them.
• Mechanical. Duct runs and supports, refrigerant line sets, condensate drains, and exhaust and ventilation ducts routed to the outdoors.
• Framing interactions. Notches and bored holes for pipes and ducts within code limits. LA's bulletin on cutting and boring sets limits for studs, joists, rafters and shear walls.
• Energy items. Some Title 24 field verifications happen before walls close. The California Energy Commission's 2025 ADU guidance includes ECC verification of installed insulation in some cases.

Have these on site

• A copy of the permit and the approved plans. LADBS lists these, along with the building card for building permits.
• Manufacturer installation instructions for equipment, which San Diego lists among the items to make available.
• Safe access, such as a ladder. LADBS asks for any equipment needed for the inspection.

Before you call for the inspection

1. Walk each room with the MEP sheets and confirm outlets, fixtures and equipment are where the plans show them.
2. Complete any required pipe tests so they can be observed.
3. Leave everything uncovered until the inspector signs off.

What this means for your MEP plans

The inspector checks the work against the approved sheets, so give every trade the approved set and flag any field change before it is built. LA's guide tells owners to return to plan check if construction will vary from the approved plans. See garage conversion inspections, field verification testing and HVAC installed differently than shown. Inspection practices vary, so confirm with your building department.

Sources: dbs.lacity.gov, sandiego.gov, dbs.lacity.gov, energy.ca.gov, dbs.lacity.gov.