PROBLEM TO BE SOLVED: To provide a method of manufacturing a coated building material for outdoor applications, e.g. sectional door panels or overhead door assemblies, or a building material for facade integrated with a door and/or a door assembly in the fixtures industry.SOLUTION: A relative motion in the feeding direction is generated between a starting material for production a building material and a coating mechanism, and a coating material is applied from the coating mechanism to the starting material along a coating direction intersecting the feeding direction and being essentially orthogonal to the main surface to be coated. In the process in which the coating material moves perpendicularly in the coating direction and relatively between the starting material and the coating mechanism, the amount of the coating material applied to one surface element of the coating surface to be covered by the coating mechanism is controlled on the basis of material data representing the starting material.