Therma-Tru provides a simple tutorial on how to check if a door unit is plumb, (true vertical alignment of the lock and hinge jambs) level, (a flat or even surface) and square (four corners are perfect angles). If the door unit is not plumb, level, and square. Then, contact a professional contractor as this may affect the operation of the door. Feel free to contact Therma-Tru with questions or concerns about maintaining a door unit.
