Fiberglass ranks among the best and most popular building materials used in modern construction, not just in windows, but doors, roofing, and interior design. Most people think of boats and land vehicles when they hear the word “fiberglass.” That may be because gorgeous windows and French doors, for instance, are made from this material. Fiberglass window and door frames are made of glass fibers and resin. These materials hardly contract in extreme weather and temperature changes, making these frames great at resisting swelling, rotting, and warping. The design of fiberglass windows and doors allows durable frames that are perfect for any home in any type of climate.