Frame Elevations are drawn with a Polyline.
Rough Openings are drawn with a Polyline.
STEP 1: INSERT and EXPLODE the BLOCK you need into your drawing.
STEP 2: STRETCH and add mullions as needed. (NOTE: Draw Mullions with a 2" face).
STEP 3: COPY the Rough Opening lines to the appropriate location and dimension as needed. (NOTE: The Rough Opening stretched with the elevation as it was being modified.)
FYI: Rough Openings are measured from the frame rabbet as follows:
JAMBS – add 5/8" per side