When installing a door frame, it is critical that the frame is level and plumb in order for the door to operate properly. An A-frame that has not been leveled will cause the door to sag, which will result in friction between the door slab and frame. Leveling a door frame can be accomplished in three quick steps.
Level the Jamb
The first step in leveling a door frame is to level the hinge side jamb first. Use the 4-foot level and a package of wood shims to work your way up from the bottom of the jamb to the top. The shims will allow you to make minute adjustments to level off the jamb. If you’re installing a pre-hung door, remove the slab so the frame is easier to maneuver.
Level the Header
The next step is to level the header of the door frame. This can be accomplished using a 2-foot or torpedo level, depending on the width of the door. Make sure the level is flush with the frame to get an accurate reading. Again, use the shims to make any adjustments and make sure to position the fasteners so that they catch the shims as well.
Level the Opposite Jamb
The last step involves leveling the opposite jamb of the door frame without using a level. You’ll want to make sure there is an even gap between the door slab and frame. Hang the door slab on the frame and shut the door. Then use the shims to adjust the non-hinged jamb so that the opening between the frame and slab is consistent.