Pros and Cons of Shimming doors in the jambs
A. Leaving the door in the jamb saves time because you need the door in the frame in order to square the jamb to the door.
B. The cons are: It can be quite cumbersome (especially with heavy doors), often times this method requires two people. It is impossible to add shims from both sides of the door without a second person.
Pros and Cons of Removing a door to shim
A. The door frame is much easier to handle with the door intact.
B. The cons are: Often more time consuming as you’ll need to re-install the door to the hinges to square it with the jamb.
3. In these instructions we will assume the door is left in the jamb. Place shims between the door frame and the wall by sliding them in from each side. Do this by each hinge. Nail through the face of the jamb with 2-1/2 inch finish nails under or into the shims to hold them in place. Use a 4 or 6 foot level to check for plumb.
4. Check the head (top) jamb for square and level with the previously installed hinge side of the door jamb. Shim the middle and attach to the wall with 2-1/2 inch finish nails.
5. Place shims between the wall and the door frame on the latch side of the door. Start at the top, keeping the reveal or clearances as equal as possible.
*Tip – Make sure the door unit is flush with the edge of the drywall.
6. Trim off any excess shims protruding beyond the walls edge with a utility knife. Score both sides, this should allow them to snap off.