French Doors are a great way to fully open up a room to provide you with additional light and space to lead you to the outside world. At Thermoglaze Windows and Doors, we pride ourselves on only using the best products and materials on the market today. Our French door system has a unique locking system with shoot bolts as standard and anti-theft security key barrels as standard, and our U-values are as low as 1.3 for the double glazing option and 1.0 for triple glazing.