A door assembly comprising: a door panel having a top edge, a bottom edge, a first vertical edge and a second vertical edge, the door panel being fixed proximate the top edge to a drum, the drum being rotatable in a first direction and a second direction, wherein rotation in the first direction causes the door panel to wind onto the drum, and rotation in the second direction causes the door panel to unwind from the drum; a first side column and a second side column, wherein the first side column is positioned proximate a first side of a doorway and the second side column is positioned proximate a second side of the doorway, the first side column and the second side column each comprising a guide track (80, 82), each guide track being positioned to guide one of the first vertical edge or the second vertical edge of the door panel as it blocks and unblocks the doorway; a first column of drive teeth positioned along the first vertical edge and a second column of drive teeth positioned along the second vertical edge, wherein each of the first column of drive teeth and the second column of drive teeth are formed by a plurality of adjacent drive teeth, each drive tooth in each plurality of drive teeth abutting an adjacent drive tooth as the door panel is wound and unwound from the drum, a first drive sprocket being positioned proximate a top of the first side column and a second drive sprocket positioned proximate a top of the second side column, wherein the first drive sprocket engages the first column of drive teeth, and the second drive sprocket engages the second column of drive teeth, as the door panel is wound and unwound from the drum, a first drive guide and a second drive guide, wherein the first drive guide partially surrounds the first guide sprocket, and the second drive guide partially surrounds the second guide sprocket, and wherein the first drive guide and the second drive guide each comprise a drive channel, characterized in that each drive channel has a first recessed portion, a second recessed portion, and a narrowed portion, the narrowed portion being positioned between the first recessed portion and the second recessed portion, wherein the first drive guide facilitates engagement between the first column of drive teeth and the first guide sprocket, and the second drive guide facilitates engagement between the second column of drive teeth and the second guide sprocket. a door panel having a top edge, a bottom edge, a first vertical edge and a second vertical edge, the door panel being fixed proximate the top edge to a drum, the drum being rotatable in a first direction and a second direction, wherein rotation in the first direction causes the door panel to wind onto the drum, and rotation in the second direction causes the door panel to unwind from the drum; a first side column and a second side column, wherein the first side column is positioned proximate a first side of a doorway and the second side column is positioned proximate a second side of the doorway, the first side column and the second side column each comprising a guide track (80, 82), each guide track being positioned to guide one of the first vertical edge or the second vertical edge of the door panel as it blocks and unblocks the doorway; a first column of drive teeth positioned along the first vertical edge and a second column of drive teeth positioned along the second vertical edge, wherein each of the first column of drive teeth and the second column of drive teeth are formed by a plurality of adjacent drive teeth, each drive tooth in each plurality of drive teeth abutting an adjacent drive tooth as the door panel is wound and unwound from the drum, a first drive sprocket being positioned proximate a top of the first side column and a second drive sprocket positioned proximate a top of the second side column, wherein the first drive sprocket engages the first column of drive teeth, and the second drive sprocket engages the second column of drive teeth, as the door panel is wound and unwound from the drum, a first drive guide and a second drive guide, wherein the first drive guide partially surrounds the first guide sprocket, and the second drive guide partially surrounds the second guide sprocket, and wherein the first drive guide and the second drive guide each comprise a drive channel, characterized in that each drive channel has a first recessed portion, a second recessed portion, and a narrowed portion, the narrowed portion being positioned between the first recessed portion and the second recessed portion, wherein the first drive guide facilitates engagement between the first column of drive teeth and the first guide sprocket, and the second drive guide facilitates engagement between the second column of drive teeth and the second guide sprocket.