Rigid, thermoinsulating, movable covering for greenhouses or the like, comprising a self-supporting structure provided with a coating of thermoinsulating material or consisting of such material, adapted to move on tight sliding means in the interior or exterior of said greenhouses or the like from an inoperative position to an operative position and vice versa. Said self-supporting structure can be an enbloc structure or a telescopic structure, and said sliding means can consist of floats immersed in water.
