Screw a 2×4 Behind Each Stair Stringer Before It Goes Up

The Problem

When you frame stairs tight against a wall's studs, you leave the finisher no room to work. Whoever closes that wall has to cut drywall or a skirt board to the exact stair profile and shoehorn it around every tread and riser. It's slow, ugly work, and it was avoidable at framing time.

The Technique

A framer's standard move before any stringer goes up:

1. Screw a 2×4 flat to the back of the stringer before installing it — a full-length spacer between stringer and wall.
2. Fasten through the assembly into every stud with long structural screws — 4½ to 6 inches, enough to pass through the roughly 3 inches of stringer-plus-spacer and bite the framing. Hitting every stud is more than strength requires; do it anyway and the whole stairwell stiffens.
3. Finish the wall later by sliding, not scribing. With the stringer held 1½ inches off the studs, drywall or skirt board cuts to the stair angle and slips straight down into the gap. Half-inch drywall still leaves an inch of space for a skirt board after it.

He also doubles the center stringer with a 2×4 on each side — same principle of building in what the finished stairs will want before the treads go on.