Although there is nothing preventing you from putting the knob of your bifold door anywhere you like, there is a proper placement for it. It's in the horizontal center of the leading door, 36 inches from the floor; if the doors have panels, the knob should go in the vertical center of the middle panel instead. This placement minimizes the force needed to open and close the door.
Unlike a knob on a conventional door, a bifold knob doesn't have to latch, so the main considerations in placing it are aesthetic and ergonomic. Alternative placements that are aesthetically pleasing by satisfying symmetry include:
- The leading edge of the leading door: Too far from the pivot to give you leverage to open the door, but closing the door is very easy.
- The hinge edge of the leading door: This placement makes it easy to open the door, but closing it is more difficult.
- The hinge edge of the trailing door: You can open the doors easily, but closing them puts stress on the guide pin and may lead to failure.
- The center of the trailing door: Opening and closing the door are both more difficult with the knob in this position.
None of these placements is as good an ergonomic choice as the center of the leading door, although the hinge edge of the leading door is a close second.
Measuring for the Knob
When installing bifold doors, knob installation is usually the last procedure; the doors are typically already hung and adjusted for smooth operation. To find the standard knob location:
Measure a distance of 36 inches from the floor, using a tape measure, and make a light mark on the leading edge of the leading door, using a pencil.
Measure the width of the door panel.
Place a level on the front of the panel, align one end with the mark on the edge, center the bubble and measure half the width of the panel along its edge. Make a mark for the knob at that point.
Extend a straightedge from one top corner of the middle panel to the diagonal opposite corner.
Measure the distance between these points and draw a light light to mark the center. The line doesn't need to be longer than about 1/2 inch in length.
Extend the straightedge from the opposite pair of diagonal corners and make another line that intersects the first one. "X" marks the spot where you should install the knob.