Bi-fold garage doors might look confusing but they operate on a simple principal. Two hinges on the ends of each garage door are linked and therefore allow the door to close in a bi-fold manner. Building a bi-fold is easier than building a tri or quadruple fold door as well, because you only need to build two panels and attach hinges to two ends.
Create the two panels for the garage door. Draw up a sketch using dimensions of the garage door opening to help. Measure carefully, the garage door will close flush against the backside of the frame, so it can overlap the width or the frame by an inch on each sides.
Cut four 3x2 boards to the width and four 3x2 boards to half the height of the garage door opening, subtracting the width of the 3x2 boards to the overall length.
Fasten the boards together to create the outer frames of both panels. Then install the slating in a diagonal or vertical pattern across the frame. Tack the slats to the frame using 1 inch nails or screws.
Paint and finish the doors and let dry.
Install the hinges. These hinges can be bought at a hardware store and then should have hinge flaps or sides that are at least 3 inches long. Lay both panels together on the ground with the outside of the door facing down.Place the hinges across the seam in between the two doors and secure with wood screws or bolts on heavier doors.
Mount the rollers to the frame using the provided hardware. Install two on the bottom of the lower panel, and two at the very top of the upper panel.