A central Iowa vinyl siding maker is closing its factory, eliminating more than 100 jobs. Pennsylvania-based Certain Teed Corporation is shutting down its Grinnell plant in about two months. Company spokesman Bill Seiberlich says the economy played a significant role in the closing.Seiberlich says there is also a glut of vinyl siding in the industry, which also had a hand in the closing. Workers in Grinnell will get a severance package and have a chance to move to other CertainTeed operations in Georgia. About 112 Grinnell workers will be “released” starting in March.