I have just such a room, a dining room, that has high traffic and is also used as a temporary work space. It has 2 entrances, one from the kitchen and one from the lounge, with the 2 sets of doors being close together. One of the doorways has a double door which really protrudes into the room. One of the double doors is always clattering into the door of the kitchen and blocking the walkway space into the room.
The solution was to make the double doors from the lounge into bifolds thus tucking the doors out of the way and stopping them from clashing with the kitchen door while freeing up walkway space around the door area.
My initial search for 6 panel doors that came as readymade bifolds revealed only that they came as part of a kit where there was a track that would go along the header of the door in which the bifolded doors would run. The logic behind this was that the track was needed to support the doors when closed and keep them straight in the doorframe. This meant the doors in the kit were 30 or 40 millimetres shorter due to the track mechanism than I needed. I was planning to use thumb turned rack bolts at the top and bottom of the door to hold the doors shut so I wanted full height doors.
The only option was to take 2 standard hollow 6 panel doors and turn them into a bifold doors.
The doors were slightly too big for the opening so a line was scribed along the top with the doors with the doors being parallel to the jam on the hinge side giving the door a couple of millimetres clearance between the door and the header when cut. If the threshold of the door is not parallel with the bottom of the door then scribe a line on the bottom of the door as well. Make sure that timber removed from the top and bottom of the door leaves a gap above and below the door of a couple of millimetres. The timber was carefully removed using a fine 60 tooth bladed circular saw.
The doors were cut down the centre of the panels using the circular saw. The doors were clamped on top of 2 work benches. Cutting the doors in half revealed the hollow insides of the doors which are filled with thin cardboard. The cardboard was pushed in to allow timber battens that were planed to 27mm thick and 36mm wide to be glued in the gap and clamped.
The timber battens were allowed to set for 24 hours. The hinges were then marked up on the doors matching the existing hinge placements. The hinge housings were then cut out using a router to a depth of 1.5 times the thickness of the hinge leaves. The housing needs to be deep enough to take the hinge leaf and accept part of the depth of the hinge knuckle. See the diagram below of the parts of a hinge being the knuckle, leaf and cap.
Don’t worry if the housings are too deep as the hinge depth can be fine tuned with pieces of thin card or paper placed in the housing. Old Christmas cards or Birthday cards are good for this. I used grade 7 fire rated ball bearing hinges to give the doors stability and a smooth movement.
Clamp the 2 doors together and mark the position of the hinges that join the 2 doors together. Then using the router chop out the housings for the hinges. Fit the hinges to the 2 doors so that they join together and then hang the door into the frame. Repeat these steps for the other door. Adjust the depth of the hinges to allow the minimum gap when closed.
If the doors are too wide then trim the door on the hinge side and use the router to recreate the housings for the hinges. If the gap between the doors is too big then use cardboard or paper shims placed under the hinge to close the gap.I used thumb turns and rack bolts to finish off the doors and allow them to be locked into position when closed.