The present invention relates to a dry setting installation (1) for generating a substantially dry working space for carrying out work at an underwater structure. The dry setting installation (1) comprises two side-walls (2), a back wall (3) and a bottom (4) thus forming a cofferdam. The dry setting installation furthermore comprises, for each side-wall, a side edge sealing means (20) provided on the side-wall (2) edge for providing a substantially sealing contact between the side-walls (2) and the underwater structure. According to embodiments of the present invention, the dry setting installation also comprises a distance variation means (30) for varying the distance between the side edge sealing means (20) of the two side-walls (2).