Abstract: An apparatus designed to attach sheets, preferably insulating sheets of e.g. mineral wool to an underlying layer, such as profiled sheet metal, by using centrally apertured washers and screws that are driven through the washer and the insulating sheet and into the underlying layer, thus securing the insulating sheet thereto. The apparatus which is run across the insulating sheet, comprises means for feeding the washers, one at a time, to the desired points of attachment on the sheet, means for time and place controlled feeding of screws to the washers already deposited in place, and a drill means arranged to engage said screws so as to drive them down, through the insulating sheet and into the underlying layer.