What Do ‘Top Hung Roller t’ & ’Bottom Track Roller’ mean?

When you are buying bifold door, you may come across the terms "top hung roller” and “bottom track roller”. Basically they refer to how the weight of the doors will be distributed when the doors are folding/sliding. Of course they have different track and roller construction.

The major different is that with top hung doors, the doors are “hanging” from the top track, (so all the weight is at the top) and with bottom rolling doors they roll along the bottom track (so all the weight is at the bottom).

All bottom track roller bifold doors have tracks in the top and bottom of the frame that the doors slide along in a train fashion. However with top hung roller bifold door, the bottom track is optional although technical advise is better to have it.