The auxiliary fastening device (10) is for a shuttering board (34) used during construction of a building. The fastening device has a distance piece consisting of a cup (14) with its open end facing the board with the rim in contact with the board. There are holes (24) to allow nails to be driven in diagonally to hold the cup onto the board. There is a projection (12) extending from the bottom of the cup inward towards the centre of the poured mass of concrete it may screw into a female thread in a fitting which may be permanently embedded in the concrete.
