Ply Gem Simonton Windows & Doors is part of the Cornerstone Building Brands family. Headquartered in Cary, North Carolina, Cornerstone Building Brands is North America’s leading exterior building products manufacturer. They were founded in Pennsboro, West Virginia, in 1946, when Fred and Sybil Simonton recognized the need for high-quality exterior aluminum products and founded Pen Vent Awning. Their son would later help take Simonton to the next level.
