Framing and Substrate Preparation
What this domain tests
These questions check whether the frame is straight, solid, and backed before board goes on. Expect stud spacing and gauge, blocking locations, control joints, ceiling grid layout, and framing tolerances.
Core rules
- Wood studs at 16 or 24 in. o.c.; steel studs commonly at 16 in. o.c. for 1/2 in. board, with 24 in. o.c. only where panel thickness and assembly rating permit.
- Check framing before hanging. A common tolerance is 1/8 in. variation in 8 ft; plane or shim high studs and replace bowed ones.
- Add blocking at cabinet runs, grab bars, television mounts, and any fixture that loads the wall. It cannot be added later without opening the finished surface.
- Drive or remove protruding fasteners and framing nails; one proud nail head becomes a visible bump.
- Install control joints to relieve stress - commonly at 30 ft intervals on long runs and wherever framing changes.
- Suspended ceilings: main runners 4 ft o.c., cross tees at 2 ft (or 4 ft) o.c., grid kept square before tile goes in.
Worked example
Before tile is installed in a 20 × 30 ft ceiling, check the grid with the 3-4-5 method: measure 3 ft along one main runner and 4 ft along the perpendicular tee, then measure the diagonal between those points. It must read 5 ft. A reading of 5 ft 1 in. means the grid is out of square by about 1.1 degrees, which accumulates to roughly 4.5 in. across a 20 ft span. The border tile would taper visibly. Fix the runner spacing first; you cannot correct it with tile.
Traps that cost marks
- Hanging board over a bowed stud and expecting compound to hide it.
- Forgetting backing at a grab bar or toilet-paper holder.
- Setting door-frame track out of plumb so the casing cannot sit flat.
- Skipping control joints in a long corridor, inviting a random crack.