Think of a sandwich, with glued-on fiberglass skins as the bread and rigid insulating foam as the filling. An interior frame of wood or composite rails and stiles forms the exposed edges.your house. Glass and factory-finish warranties are another story, typically 10 to 20 years and one to three years, respectively.
Where to buy? Order through big-box stores or, for the largest selection of hardware, finish, and glass options, from an independent specialty window and door supplier.