Wondered if anyone can point us in the right direction , got a small shed with an opening of a shade over 5m by roughly 2.2m high so wanting to put a sliding door in , will be using 50mm box for door frame but having not built any doors in tracking before desperately want to keep the height of the door as much as possible so thinking of tracking that bolts to the side of channel rather than from under the channel , have rsj in flush with the walls to carry the channel but what sort of size Chanel etc , would be handy to see someone’s work and opinion how to do it and where’s best to buy tracking and runners , thanks