Sizing a Rough Opening for a Bifold Door – Finished Opening for Bifold Door

For example a four-foot wide (48”) by six feet, eight inches high (80”) Bifold set of doors, would require a rough opening width of 50 inches and a height of 82 inches. This sized finished opening for a bifold door will allow for either a doorjamb kit to be installed or for ¾” thick select lumber to be used to create the finished doorjamb. Note that most bifold door assemblies do not come with a doorjamb kit so using ¾” thick select lumber to create the finished doorjamb is fairly common.

What is Finished Opening for Bifold Doors – An Important Note

Again, the bifold closet door opening should be trimmed out first, and thus be accounted for in sizing a bifold door rough opening. 

The finished opening for bifold doors involves the fastening of 1″ x N” trim boards to the bifold door rough opening 2×4 framing studs. The 1″ thick trim boards, however, are in reality only 3/4″ thick. Thus the bifold door finished opening should be 1.5″ narrower than the rough bifold door opening, due to the installation of the finished trim boards.

How to Install Bifold Doors

The bifold door mechanical bracket assemblies actually screw into this finished doorjamb so it is important that the doorjamb be installed plumb and level.

To complete the interior trim work associated with the doorjamb, when using ¾” select lumber, case moulding is wrapped around the perimeter of it. For best results, mitered cuts are employed. See this eBook on how to install interior door trim. Sizing a Bifold Door Rough Opening for a Sheetrocked Wrapped Opening If the Bifold door is to be installed into a sheetrocked wrapped opening the rough opening width should be sized to the actual width of the Bifold doors (48” in the case of this example). The rough opening height should be the height of the door plus 3/4″ (80 ¾” in the case of this example).

Note that these guidelines for a finished opening for a bifold door are typical framing standards that are employed in the home construction business. You should always check with the manufacturer or product specifications to confirm the rough opening requirements for your particular bifold doors.