When do you call for drywall inspection?
Drywall (gypsum board) inspection shall be made after the interior drywall is in place, but before joints and fasteners (screws and nails) are taped and finished.
Inspectors shall be able to verify the drywall screws or nailing that were installed according to the residential codes. (IRC 109.1.4.2) (CRC 109.1.4.2).
Gypsum board definition
The generic name for a family of sheet products consisting of a noncombustible core primarily of gypsum with paper surfacing.
Drywall thickness and minimum fasteners spacing code requirements
This table shows the installation of the drywall according to the International and California residential codes.
Drywall screws requirements
All screws are gypsum board type “W” or “S” unless otherwise noted and long enough to penetrate a minimum of 5/8” into wood and 3/8” into steel.(CRC 702.3.5.1) & (IRC 702.3.5.1).
Drywall nails requirements
| Drywall thickness (inches) | Size of nails to wood framing |
| 1/2 | 13 gage, 13/8” long, 19/64” head; 0.098” diameter, 11/4” long, annular-ringed; 5d cooler nail, 0.086” diameter, 15/8” long, 15/64” head; or gypsum board nail,0.086” diameter, 1 5/8” long, 9/32” head. |
| 5/8 | 13 gage, 15/8” long, 19/64” head; 0.098” diameter, 13/8” long, annular-ringed; 6d cooler nail, 0.092” diameter, 17/8” long, 1/4” head; or gypsum board nail, 0.0915” diameter, 17/8” long, 19/64” head. |
Related: A Complete Guide for drywall installation Read more.
Water-resistant gypsum board
The residential codes allow the use of the water resistant drywall inside the dwelling unit with the following limitations (CRC 702.3.7) & ( IRC 702.3.7)
- Water-resistant gypsum backing board used as the base of ceramic tile or other required nonabsorbent finish material shall conform to ASTM C1178, C1278 or C1396.
- It shall not be used where there will be direct exposure to water (shower walls), or in areas subject to continuous high humidity.
- It shall not be installed over a Class I or II vapor retarder in a shower or tub compartment. Cut or exposed edges, including those at wall intersections, shall be sealed according to the manufacturer.
- It shall be permitted on ceilings. It is recommended where framing spacing does not exceed 12 inches on center to use ½ inch, or 16 inches O.C to use 5/8 inch thick gypsum board.
Wood framing supporting drywall
Wall and ceiling wood framing supporting drywall shall be minimum of 2 inches thick (2 by stud / 2 by joist) except that wood furring strips minimum 1-inch by 2-inch shall be permitted to be used over solid backing or framing.(IRC 702.3.2) (CRC 702.3.2).
Related: What is better Drywall or Plaster Read more.
Garage fire separation
Most of the contractors and homeowners misunderstand the requirements of the fire separation between the dwelling unit and garage and call it one hour firewall which is not correct.
The fire separation is required to be installed on the garage side only from the sill plate to the under roof sheathing. If a sleeping area located above the garage, it is required to install a fire separation covers the whole ceiling.
| Locations | Drywall thickness(inches) | Comments |
| Common walls without living space above the garage | 1/2” | From the finished grade to the roof under sheathing |
| Common walls with living space above the garage | 5/8” type X | walls and ceiling |
Drywall requirements under-stair
Accessible enclosed area under stairs with a door or/and access panel shall have walls covered with a minimum of 1/2 inch gypsum board. (R302.7).
Reference Codes – International Residential Code – California residential Code
