Patent ID: 8084098

Claim:
A coating method for coating a building board having an upper surface with both a convex portion and a concave portion, and the building board having side surfaces, comprising the steps of: providing a transportation line for transporting a building board, a tank of a coating material having a drain hole at a lower end thereof and a stopper for regulating a flow of the coating material in proximity of the drain hole and inside the tank, the tank being disposed above the transportation line, and a flowing direction change member for the coating material being disposed along the transportation line; transporting the building board on the transportation line under the tank, the upper surface of the building board facing to the drain hole of the tank; supplying the coating material to the tank; and applying the coating material in the tank to the building board through the drain hole of the tank so that the coating material flows from the upper surface of the building board to the side surfaces thereof, while transporting the building board on the transportation line, wherein the building board has a side surface having a shiplap portion and a side edge face adjoined with and under the shiplap portion, the building board is placed on the transportation line so that the side surface having the shiplap portion and the side edge face is aligned with the transporting direction of the building board on the transportation line, the flowing direction change member is disposed on the transportation line along transporting direction of the building board and a part of the flowing direction change member is disposed directly under the shiplap portion of the transporting building board so that the flowing direction change member faces towards and is 5-50 mm away from at least one of the side surfaces having the shiplap portion and the side edge face of the building board, the drain hole width in a direction perpendicular to the transporting direction of the building board being wider than the building board width in a direction perpendicular to the transporting direction of the building board, the stopper size is bigger than the drain hole size and is located immediately above the drain hole of the tank, the coating material between the stopper and the drain hole flows out of the drain hole in a weight fed flow, the coating material is applied to the building board so that an amount of the coating material applied to the upper surface of the building board is 1200-1800 g/m 2 , and a flowing direction of a part of the coating material flowing out from the drain hole is regulated by the flowing direction change member so that the shiplap portion and the side edge face of the building board are coated by the coating material.