Metal doors should be stored vertically on their _______ edge?

Metal doors should be stored vertically on their long edge to ensure stability and prevent warping or damage. When stored vertically, the long edge provides more surface area, which supports the door's weight evenly and minimizes the risk of bending or other deformities. This vertical storage method also makes it easier to handle and transport the doors without the risk of them falling over or being improperly supported.

Storing doors on their short edge or flat can create uneven pressure and increase the likelihood of warping, which can compromise the door's structural integrity and functionality. Therefore, handling metal doors by keeping them upright on their long edges is essential for maintaining their quality until installation.