It would depend on the installation method you are using.
Through-Wall Installation: Construct a rough-in opening of approximately 22.5 x 22.5 inches through the wall.
Window Installation: Fits a minimum window opening height of 21.6 inches and a minimum width of 29.25 inches (with a maximum window width capability up to 33 inches).
Duct / Core Opening: The bare fan duct opening without the grill measures roughly 20 x 20 inches (specifications also note the internal discharge dimensions at roughly 21-3/4 x 21-3/4 inches for framing alignment).





