Abstract: A wall panel system including a mounting bracket, a wall panel, and a clip attached to the wall panel, the clip having an engaging element that secures it to the mounting bracket. The wall panel system also includes a slot in the clip facing outwardly from the wall panel, a spline slidably positioned in the slot of the clip, and a sealing insert positioned between the mounting bracket and the spline. The sealing insert may be in the shape of an X, and may be made from polypropylene foam. The sealing insert may also have a gasket tape on one side to provide an improved seal.