To ensure our sliding doors operate smoothly an important step in installing our doors is to make sure the sill brace is used in conjunction with a 10mm packer between the subsill and sill brace. As each door panel can weigh up to 300kg there is a lot of downward force on each track. Without proper support the track will bend in on itself. This makes the seals between the door panel and track compress. Even a milometer or two of extra pressure can have a dramatic effect on the doors ability to operate smoothly.