A bifold door can be used as a decorative way to separate two rooms in a home, or as a closet or storage area door. You can use your bifold door in a low threshold area provided you create a threshold that is sunk into the floor enough to accommodate the opening between the rooms you are dividing. Low thresholds require special preparations for bifold doors if you plan on using standard size doors. Your other option is to special order smaller bifold doors that will fit easily into your existing low threshold. When you decide to put bifold doors in a low threshold, make sure your measurements are accurate.