Drywall Installation
What the Installation domain tests
Installation questions cover panel selection, layout, cutting, and fastening - the decisions that determine whether the finished wall is flat and stays that way. Expect to choose a thickness or fastener for a given condition, pick a screw spacing, or identify a layout mistake.
Core rules
- Panels are 4 ft wide and commonly 8, 10, 12, or 14 ft long. 1/2 in. is standard for walls; 5/8 in. is commonly specified for ceilings on 24 in. framing and for fire-rated Type X assemblies.
- Run panels perpendicular to framing where possible. It stiffens the assembly and reduces the number of butt joints.
- Stagger end joints between adjacent rows by at least one framing member. Never align a butt joint with the corner of a door or window opening.
- Fasteners: Type S coarse thread for wood, Type S-12 fine thread for steel studs, Type G for gypsum to gypsum. Drive to a dimple - head just below the surface, face paper unbroken.
- Common spacing: 16 in. o.c. in wall fields, 12 in. o.c. in ceiling fields, 7–8 in. o.c. along edges and butt joints.
- Leave roughly a 1/2 in. gap at the floor and do not jam panels tight into corners.
Worked example
A 4 × 8 panel must fit a wall with a receptacle box 18 in. above the floor and 40 in. from the left corner. Measure from the same two edges that will register against the floor and corner, mark the box center, then transfer the marks to the back of the panel - the sheet is flipped when it goes up, so a face-side measurement alone puts the hole on the wrong side. Cut the opening about 1/8 in. larger than the box all around. If you measured from the top edge instead of the bottom, the opening is mirrored and misses the box entirely.
Traps that cost marks
- Overdriving screws and breaking the paper, which destroys holding power and causes pops.
- Running coarse-thread wood screws into 25-gauge steel studs; they strip instead of gripping.
- Butting panel ends tight to floors and corners, which leads to cracking and moisture wicking.
- Hanging panels parallel to framing on a ceiling, adding butt joints and sag.