Abstract: Assembly element for fixing a supporting profile on a solid ground with at least two opposite, outward turned flanges extending in the longitudinal direction of said supporting profile, whereby this assembly element comprises an elastic, compressible vibration isolator with a slot in which can be put a flange of the supporting profile, such that the supporting profile is acoustically insulated in relation to the ground, whereby the vibration isolator is formed of at least two parts defining the slot and which allow the vibration isolator to assume an open position, whereby the parts of the vibration isolator are at least partly removed from one another so as to put the flange of the supporting profile at least partly in the slot, and to assume a closed position, whereby the above-mentioned parts are moved towards one another and the vibration isolator is compressed so as to press together the slot when the flange of the supporting profile is at least partly situated inside the slot, such that the flange is cl