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. The Simonton portfolio of products includes 12 different window and patio door lines with varying structural and stylistic features, all of which can be ordered to meet ENERGY STAR® guidelines. In addition, Simonton is committed to always exceeding customer expectations with the highest‐quality products available and unbeatable service.