How to Shim a Door Frame
- 1). Center the new door frame into the opening. If the frame comes with a prehung door, close the door. Hold a 4-foot level against the frame's hinge side.
- 2). Slide wooden shims between the door frame and the rough opening in three places; behind the top, middle and bottom hinges. Shims are wedge shaped, so the further you push them in, the further out they push the frame. Adjust the shims until the frame's hinge side is firmly positioned straight up and down. Use two shims behind each hinge, if necessary, to achieve the perfect spacing.
- 3). Use a drill and a Phillips-head drill bit to insert drywall screws through the frame, shims, and into the rough opening. Screws are used on this side instead of finishing nails because they hold the frame in place better throughout years of use.
- 4). Lift or lower the door frame's knob side so that the gap between the frame's top board and the rough opening is equal all the way across. Place a level against the frame's knob-side board.
- 5). Insert shims at approximately the same heights as the previously installed shims. Once the frame's knob-side board is straight up and down, use a pneumatic nailer and 2 1/2-inch finishing nails to secure the frame in place. Insert the nails through the frame, shims and rough opening.
