Recommended Opening Sizes for Hollow Metal Frames
Interior Knockdown Frames that Wrap Wall
A = opening width + 2″
B = opening height + 1″
The rough opening would be 38″ x 85″
for a 3’0″ x 7’0″ door & frame
Note: For fire rated openings, drywall must extend at least 1/2″ into frame.
Frames that Butt Wall (Block or Exterior Wood Stud)
A = opening width + 4-1/2″
B = opening height + 2-1/4″
The rough opening would be 40-1/2″ x 86-1/4″
for a 3’0″ x 7’0″ door & frame. O.D. of frame is 40″ x 86″, as the frame face is 2″ around all 3 sides. Use shims and/or caulk to seal gaps between wall and frame.
Timely Prefinished Interior Steel Frame
A = opening width + 1-1/4″
B = opening height + 1″
The rough opening would be 37-1/4″ x 85″
for a 3’0″ x 7’0″ door & frame
More info on Timely rough openings: Click Here
KD Hollow Metal Sidelite Frame
A = opening width + sidelite + 2″ for each mullion + 2″
B = opening height + 1″
A 3’0″ x 7’0″ door & frame with a 12″ sidelite
would have a rough opening of 52″ x 85″