Unless a window is very large, I usually install it by myself. Over the years I’ve played with a few variations of how to install a window without it falling out of the opening while I move from inside to outside to check its placement. The simplest method I have come up with is to use a quick-adjusting clamp or two on the top jamb extension with the bar pointing up toward the ceiling. If the window starts to tip out of the opening, the bar on the clamp keeps it from falling. This technique also leaves the window free for leveling in the rough opening before attaching the nailing fins on the exterior.
—Curt Lyons, Fort Collins, Colo.
Edited and Illustrated by Charles Miller
From Fine Homebuilding #285