Question

when installing a prehung door, what should be done with the factory - installed spacer shims between the door and the frame?
leave in place permanently
remove before installation begins
remove after the door is attached to the rough opening
remove when the door is in place, but before attaching it to the rough opening

Explanation:

Factory - installed spacer shims are temporary. They are used to maintain the door's position during transportation and storage. Once the door is attached to the rough opening (the framed opening in the wall), the shims are no longer needed and should be removed.

Answer:

remove after the door is attached to the rough opening