Abstract: The invention relates to a method for flush mounting a washing unit in a working leaf or the like and a strip to be used with this method. An opening corresponding to the washing unit (2) is made in the working leaf (1), while the strip (6, 22, 29) is fastened to the working leaf edge which defines this opening so that the upper edge (9) of the strip substantially joins the upper surface (14) of the working leaf (1). The strip in cross-section is substantially U-shaped, wherein the peripheral edge (17) of the washing unit (2) has a thickness greater than the distance between the ends of the legs (11, 12) of the strip. The lower leg (12) of the strip is a relatively rigid carrying flange, while the upper leg (11) is a relatively soft resilient sealing ribbon. The washing unit (2) is positioned with the one surface of its peripheral edge (17) on the one leg of the strip (6, 22, 29) and thereafter the other leg of the strip is applied to the exposed surface of the peripheral edge of the washing unit.