ADU Drywall: The Pre-Drywall Checklist That Prevents Opened Walls
If you're managing your own ADU build in San Diego, the order of work isn't optional — it's code. Miss one item before drywall goes up, and you may be tearing it back down after final inspection. This is the sequence SGP walks through on every ADU job.
Before drywall goes up in any ADU, San Diego County requires a cover inspection (CRC R109.1). Rough framing, electrical, plumbing, HVAC, fireblocking, and insulation must all be signed off before a single sheet is hung. No exceptions — not even on garage conversions or small additions.
Why the Order of Work Matters
The cover inspection is a mandatory checkpoint required by the California Residential Code and enforced by San Diego County Building & Safety Services. Once drywall is installed, inspectors cannot verify what's inside the walls. If they find a violation at final — a missing fireblock, an improperly supported pipe — the fix requires opening finished walls. This checklist prevents that scenario.
The Pre-Drywall Checklist (All 9 Items)
Work through these in order. Each item corresponds to a required inspection or a code requirement that must be satisfied before your drywall crew shows up.
Permits Pulled and Active
All permits for the ADU — structural, electrical, plumbing, mechanical — must be pulled and active before work begins. The permit card must be posted on site and accessible to inspectors. Confirm permit status through San Diego County's online portal before calling any trade for rough-in work.
CRC R105SD County PDS 498Framing Inspection Passed
Rough framing must be inspected and approved before any finish work begins. Inspectors check stud spacing, header sizing, blocking at bearing walls, structural connections, and confirmation that the framing matches the approved plans. Nail patterns and hardware are also verified.
CRC R602.6CRC R301Rough Electrical Cleared
All rough electrical wiring, boxes, and conduit must be inspected before cover. This includes outlet and switch box heights, circuit routing, panel connections, smoke and CO detector locations, and AFCI/GFCI protection. In the City of San Diego, electrical rough-in inspections are coordinated through the City's DSI desk.
NEC Article 300City of SD IB 400Rough Plumbing Cleared
All supply lines, drain/waste/vent (DWV) piping, and fixture rough-ins must be inspected and pressure-tested. Pipe supports, hanger spacing, and protection plates where pipes penetrate framing must all be in place. Horizontal drain pipes must have the correct slope — 1/4 inch per foot minimum.
CPC §313CRC R602.6.1Rough HVAC Ductwork Cleared
All duct runs, registers, supply/return boots, and mechanical rough-in must be approved. Mini-split refrigerant lines running through framing also require inspection. Under Title 24, duct systems in new ADU construction must meet leakage standards — confirm your mechanical contractor is aware of the testing requirements.
CMC §601Title 24 Part 6Fireblocking Complete
Fireblocking must be installed at all concealed vertical draft openings — top and bottom plates, stair stringers, ceiling/floor intersections, and soffits. Any penetrations through plates (pipes, wires, ducts) must be sealed with an approved fireblocking material or a UL-listed intumescent sealant before cover inspection.
CRC R302.11Fire-Rated Assemblies Confirmed
ADUs attached to or above garages require fire-rated separation walls and ceilings. California requires a minimum 1/2-inch Type X gypsum on the garage side of any living space (CRC R302.6), and 1-hour fire-rated assemblies where ADU living space is adjacent to the garage ceiling. Confirm that your drywall type, thickness, and fastener pattern match the rated assembly listed on your approved plans — inspectors check board markings.
CRC R302.3CRC R302.4CRC R302.6GA-600Insulation Inspection Passed
Title 24 Part 6 requires specific R-values for walls, ceilings, and floors in new ADU construction. Insulation must be installed and inspected before drywall covers it. Batt insulation must fill the cavity without gaps, voids, or compression. Verify your insulation R-values match what is on the approved energy calculations — inspectors compare the installed product against the Title 24 compliance report.
Title 24 Part 6CRC R316Backing and Nail Plates Installed
Before drywall goes up, blocking must be installed for anything that will be wall-mounted after finish: grab bars, heavy shelving, TV mounts, upper cabinet rails, towel bars in wet areas, and bathroom accessories. Nail plates are required wherever wires or pipes pass within 1.25 inches of the face of a framing member.
GA-216CRC R602.6.1What the Cover Inspection Actually Checks
The San Diego County cover inspection is typically scheduled 24–48 hours in advance through the county's online permitting portal. Inspectors verify all of the following before signing off — if any item is missing, the inspection fails and a re-inspection must be scheduled.
- Framing matches approved structural drawings — stud spacing, headers, hardware, and connections
- All rough electrical wiring is run, boxes are set, and nail plates are installed where required
- Plumbing supply and DWV are complete, pressure-tested, and properly supported
- HVAC ductwork or refrigerant lines are run, sealed, and secured
- Fireblocking is installed at all required locations — plates, soffits, stairwells, and pipe penetrations
- Fire-rated assemblies use the correct board type and fastener schedule per the approved plans
- Insulation is installed at specified R-values without gaps, voids, or compression
- Any corrections from previous inspections have been resolved and documented
A failed cover inspection delays your drywall start — typically 3 to 5 business days while corrections are made and a re-inspection is scheduled. On ADU projects, that delay cascades through finish trades. Getting all nine items right the first time is the only way to hold your schedule.
6 Mistakes That Cost Owner-Builders the Most
Starting drywall before cover inspection sign-off
This is the single most expensive mistake. Inspectors who arrive to find drywall already installed will issue a stop-work order and require the work to be exposed. In San Diego, this can add weeks and thousands in additional labor costs to a project that was on schedule.
Using standard 1/2-inch drywall on fire-rated separation walls
CRC R302.6 and R302.3 require Type X gypsum board for garage/living space separations and ADU party walls. Standard drywall — even 5/8-inch regular — is not equivalent to 5/8-inch Type X. The inspector checks the board markings. The fix is tear-out and replacement.
Missing nail plates on wires and pipes near the framing face
Any wire or pipe within 1.25 inches of the face of a framing member requires a steel protection plate (CRC R602.6.1). These are quick and inexpensive to install during rough-in and consistently flagged during cover inspections when skipped.
No backing for future wall-mounted fixtures
Owner-builders often skip backing because fixture placement isn't finalized at framing time. Once walls are closed, adding a grab bar, heavy cabinet, or wall-mounted TV requires cutting finished drywall, adding blocking, patching, and retexturing. Mark backing locations on your framing plans before the cover inspection.
Standard drywall in wet areas behind tile
Regular gypsum board — including moisture-resistant "green board" — is not approved as a tile substrate in wet areas under California code. Shower surrounds and tub walls require cement board, DensShield, or an equivalent water-resistant backer. Standard drywall behind tile will saturate, swell, and cause tile failure within a few years.
Skipping resilient channel for sound-rated assemblies
If your ADU plans call for RC-1 channel to achieve an STC or IIC rating, it must be installed before drywall — there is no retrofit option. Skipping it to save a few hundred dollars at framing eliminates the entire sound control assembly. This is an irreversible decision made at the worst possible time.
5 Questions to Ask Before Your Drywaller Starts
If you're the owner-builder managing subcontractors, these questions separate experienced drywall crews from those who will create problems at final inspection. A knowledgeable drywall contractor answers all five without hesitation.
"Who is pulling the drywall permit — you or me?"
On new ADU construction in San Diego County, drywall work typically requires a permit. Know upfront who is responsible. A contractor pulling the permit under their license assumes liability for code compliance. If they say you don't need one, get a second opinion from the county building department.
"What board type and thickness are you using on this wall?"
Listen for specifics: "5/8-inch Type X on the garage wall per the fire-rated assembly," "cement board in the shower surround," "1/2-inch standard on interior partitions." Vague answers — "whatever the plans say" — without specifics are a yellow flag on an ADU job where board type is code-critical.
"How are you handling fireblocking at the top plates?"
An experienced crew walks every plate penetration with approved fireblocking material before calling for inspection. A crew that says "the framer handles that" may be technically correct on some jobs — but they should know who is responsible on your specific project before work begins.
"Has the cover inspection been signed off yet?"
You already know the answer before you ask — but this tests whether your drywaller will push you to start before it's cleared. A contractor who says "we can start while we wait for inspection" is one you do not want in your walls. The correct answer is an immediate no.
"What happens if the inspector flags an issue on your scheduled start day?"
Tests flexibility and field experience. A solid answer: "We hold until corrections are made and re-inspection is cleared — starting before that puts everyone at risk." A concerning answer: "We'd just cover it and address it at final." That second answer has cost San Diego owner-builders real money.
Code References & Resources Used in This Article
Ready to Talk Through Your ADU Drywall Plan?
SGP Drywall works directly with owner-builders across San Diego County — from permit coordination to cover-inspection-ready installation. We have been through hundreds of ADU cover inspections and know exactly what San Diego County inspectors look for. We hang the right board, in the right location, the first time.
From rough framing to taped and textured walls, the hanging and finishing is the drywall installation phase of your ADU build.
If you are still choosing materials, here is why 5/8-inch is usually the right drywall for an ADU.