Multi-screw extruder for treating plastics material, with - a housing which has a plurality of housing portions (3 to 7) and in which at least two housing bores (10, 11) which are parallel to each other and penetrate each other are formed, - at least two shafts (12, 13) which are arranged concentrically in the housing bores (10, 11) and are rotationally drivable about associated axes of rotation (15, 16), - a plurality of treatment elements (31 to 36) for treating a plastics material, said treatment elements being arranged one behind another in the direction of the respective axis of rotation (15, 16) on the at least two shafts (12, 13) for rotation therewith and being formed so as to tightly mesh with one another, - at least one heat-insulating hood (54; 54a; 54b), wherein each heat-insulating hood (54; 54a; 54b) is arranged on one of the housing portions (4, 6; 3, 7; 5) and has at least one upper part (57; 57a; 57b) for the heat insulation of an upper wall of the housing portion (4, 6; 3, 7; 5) and at least one side part (55, 56; 55b) for the heat insulation of a side wall (78, 79) of the housing portion (4, 6; 3, 7; 5) in such a manner that the at least one upper part (57; 57a; 57b) and the at least one side part (55, 56; 55b) are designed as a modular construction kit and are arranged releasably on one another for the heat insulation of the housing portion (4, 6; 3, 7; 5), wherein a first heat-insulating hood comprises precisely one upper part for the heat insulation of the upper wall of the associated housing portion (4, 6) and precisely two side parts (55, 56) which are of L-shaped design in cross section for the heat insulation of the side walls (78, 79) and of a lower wall of the associated housing portion (4, 6), and wherein a second heat-insulating hood comprises precisely two upper parts for the heat insulation of the upper wall of the associated housing portion (3, 7), said upper parts forming a passage opening for an extruder component, and precisely two side parts (55, 56) which are of L-shaped design in cross section for the heat insulation of the side walls (78, 79) and of a lower wall of the associated housing portion. - a housing which has a plurality of housing portions (3 to 7) and in which at least two housing bores (10, 11) which are parallel to each other and penetrate each other are formed, - at least two shafts (12, 13) which are arranged concentrically in the housing bores (10, 11) and are rotationally drivable about associated axes of rotation (15, 16), - a plurality of treatment elements (31 to 36) for treating a plastics material, said treatment elements being arranged one behind another in the direction of the respective axis of rotation (15, 16) on the at least two shafts (12, 13) for rotation therewith and being formed so as to tightly mesh with one another, - at least one heat-insulating hood (54; 54a; 54b), wherein each heat-insulating hood (54; 54a; 54b) is arranged on one of the housing portions (4, 6; 3, 7; 5) and has at least one upper part (57; 57a; 57b) for the heat insulation of an upper wall of the housing portion (4, 6; 3, 7; 5) and at least one side part (55, 56; 55b) for the heat insulation of a side wall (78, 79) of the housing portion (4, 6; 3, 7; 5) in such a manner that the at least one upper part (57; 57a; 57b) and the at least one side part (55, 56; 55b) are designed as a modular construction kit and are arranged releasably on one another for the heat insulation of the housing portion (4, 6; 3, 7; 5),