How to Install Select Pine Door Jambs

Measure the width and height of the doorway precisely. Mark any areas that are uneven or stick out from the rest of the doorway. Hold the carpenter's level up against the frame and mark any sections that are not level. Cut out the doorway until the width and height of the opening matches the dimensions of the door plus the thickness of the select pine door jambs plus an eighth of an inch for clearance.

Re-level the frame and adjust any sections that are not level using a reciprocating saw or a file.

Cover the exterior of the door jambs with caulking. Position the door jambs in place against the doorway. Drill holes through the jambs every 12 inches into the frame of the doorway behind the jambs. Set 3-inch screws in the holes and drill them flush with the door jambs, setting the screw heads slightly recessed into the wood of the jamb.

Position the carpenter's level against the horizontal and vertical jambs and tighten or loosen each screw as needed to make the jambs level. Measure the distance between the jambs to ensure that the door will still fit within them. Set the door in place and adjust any sections of the jambs that prohibit the door from being straight, or any gaps between the door and the jambs.