A screed box includes a screed bucket, a screed plate mount attached to the screed bucket, a screed plate slidably connected to the screed plate mount and a screed bar attached to a bottom of the screed bucket. The screed plate mount includes a sealing edge. The screed plate includes at least one screed flange. The screed bar includes a body and a sealing lip including at least one projection. The screed bar is slidable between an open position where the sealing lip engages the sealing edge and a closed position where the sealing lip is disengaged from the sealing edge, and the at least one projection engages the sealing edge when the screed bar is in the open position and when the screed bar is in a closed position.