Most large windows are divided into smaller panels separated by steel T bars or stacked in the case of stone windows. They are supported against buckling by horizontal steel support bars. The 2 windows shown below and to the left were the largest single panels I have come accross. Measuring 10 feet by 5 feet with an extra layer of glass in some areas and reinforced with inch thick steel bars, they required extra thought and effort along with extensions on one of the work benches to handle the size. Weighing close to 300 pounds, simply moving them was a feat.
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The blue arrows in the photo on the left show three of the many cracks that ran through the windows in this beautiful stone church located in Castleton, North Dakota and listed on the national register of historic buildings. Such windows achieve intricate repeated patterns by silk screening onto the glass with vitreous glass paint( glass paint is fired in a kiln and bonds like a glaze on pottery to the glass.

A new set of silk screens were made to get the same look as the originals.