This type of uPVC door (www.doubleglazeddoorsfitted.co.uk/cost-guide-for-double-glazed-doors)has 2 separate sections for the top & bottom half of the door, the top section can be opened independently of the lower section and is perfect for added ventilation without having to fully open the door – a classic “farmhouse” look.
Glass should be toughened and meet British standards specification.
Q:How much will the doors cost ?
A: Get the job surveyed by a reputable installer! A Cost Guide to Bifold Doors Prices