Abstract: A fastening device for anchoring a sealing strip on a roof includes an elongated fastener which penetrates both a holder and the sealing strip and has a drill tip at a lower end thereof extending into the roof substructure. An opposite upper end of the fastener has an enlarged upper end engaged in an opening in the holder to press the holder against and anchor the sealing strip on the roof. A cover having a recessed underside for receiving the holder and a central hole with a slit-like depression for receiving a catch-shaped projection extending upwardly from the head of the fastener is rotated to drive the fastener and the holder into position on the sealing strip while at the same time covering the opening in the holder to prevent entry of rainwater and the like. As the cover engages the sealing strip, the cover eventually disengages the fastener so that only the cover rotates.