A mine stopping comprising a plurality of elongate extensible panels extending vertically from the floor to the roof of a passage in a mine. The panels impede the flow of air through the passageway except for a space at a side of the passageway because of irregularity of the side of the passageway. The stopping further has means for impeding the flow of air through the space comprising at least one side extension for the stopping. The side extension comprises a bar and a relatively long and narrow plate secured to the bar with a portion of the bar projecting from one end of the plate constituting its inner end. The extension is mounted on one face of the stopping extending generally horizontally with the plate in a generally vertical plane and extends into the space for blocking it. The projecting portion of the bar lies against the face of the stopping and has means for securing the projecting portion of the bar to the stopping.
