A box-like body (1a; 1b; 1c; 1d; 1e) for installing components of plumbing systems within masonry, comprising: - a base half-shell (2a; 2b; 2c; 2d; 2e) provided with a base wall (3a; 3b; 3c; 3d; 3e), from which protrusions (4a; 4b; 4c; 4d; 4e) extend which define at least one seat (30, 31, 32, 33, 34, 35) for at least one portion of at least one component to be installed; - a locking element (5a; 5b; 5c; 5d; 5e) which can be associated with said base half-shell (2a; 2b; 2c; 2d; 2e) and can engage the at least one component to be installed in order to lock it in said seat (30, 31, 32, 33, 34, 35) with respect to said base half-shell (2a; 2b; 2c; 2d; 2e); - a covering half-shell (6a; 6b; 6c; 6d; 6e), which can be associated with said base half-shell (2a; 2b; 2c; 2d; 2e) so as to face said base wall (3a; 3b; 3c; 3d; 3e) in order to delimit, in cooperation with said base half-shell, a compartment (7a; 7b; 7c; 7d; 7e) which is intended to contain the at least one component to be installed; said covering half-shell (6a; 6b; 6c; 6d) has a covering wall (8a; 8b; 8c; 8d) which is designed to face the base wall (3a; 3b; 3c; 3d; 3e) of said base half-shell (2a; 2b; 2c; 2d; 2e), side walls of said base half shel and covering half-shel protruding from the perimetric sides respectively of said base wall (3a; 3b; 3c; 3d; 3e) and of said covering wall (8a; 8b; 8c; 8d) in order to delimit laterally said compartment (7a; 7b; 7c; 7d; 7e); said covering wall (8a; 8b; 8c; 8d) has an opening (10a; 10b; 10c; 10d) for access to the component accommodated in said compartment (7a; 7b; 7c; 7d; 7e); characterised in that said base half-shell (2a; 2b, 2c, 2d; 2d; 2e) and said covering half-shell (6a; 6b, 6c, 6d; 6e) both have side walls provided with half-openings (9a; 9b; 9c; 9d; 9d) for the passage of regions of the component to be connected to pipes or pipes to be connected to the component, said openings being then defined by the respective half-openings (9a; 9b; 9c; 9d) when coupling said half-shells together; a removable closure plate (11a; 11b; 11c; 11d) which can be positioned at said opening (10a; 10b; 10c; 10d) provided in the covering wall (8a; 8b; 8c; 8d), said closure plate (11a; 11b; 11c, 11d) having on its side designed to be directed toward said compartment (7a; 7b; 7c; 7d; 7e) at least one bar which can be coupled slidingly with a sliding seat defined in said locking element (5a; 5b; 5c, 5d; 5e), said locking element being associated by means of a screw element with a locking protrusion (14a; 14b; 14c; 14d; 14e) which protrudes from said base wall (3a; 3b, 3c, 3d; 3e), said art least one bar sliding also in said locking protrusion. - a base half-shell (2a; 2b; 2c; 2d; 2e) provided with a base wall (3a; 3b; 3c; 3d; 3e), from which protrusions (4a; 4b; 4c; 4d; 4e) extend which define at least one seat (30, 31, 32, 33, 34, 35) for at least one portion of at least one component to be installed; - a locking element (5a; 5b; 5c; 5d; 5e) which can be associated with said base half-shell (2a; 2b; 2c; 2d; 2e) and can engage the at least one component to be installed in order to lock it in said seat (30, 31, 32, 33, 34, 35) with respect to said base half-shell (2a; 2b; 2c; 2d; 2e); - a covering half-shell (6a; 6b; 6c; 6d; 6e), which can be associated with said base half-shell (2a; 2b; 2c; 2d; 2e) so as to face said base wall (3a; 3b; 3c; 3d; 3e) in order to delimit, in cooperation with said base half-shell, a compartment (7a; 7b; 7c; 7d; 7e) which is intended to contain the at least one component to be installed; said covering half-shell (6a; 6b; 6c; 6d) has a covering wall (8a; 8b; 8c; 8d) which is designed to face the base wall (3a; 3b; 3c; 3d; 3e) of said base half-shell (2a; 2b; 2c; 2d; 2e), side walls of said base half shel and covering half-shel protruding from the perimetric sides respectively of said base wall (3a; 3b; 3c; 3d; 3e) and of said covering wall (8a; 8b; 8c; 8d) in order to delimit laterally said compartment (7a; 7b; 7c; 7d; 7e); said covering wall (8a; 8b; 8c; 8d) has an opening (10a; 10b; 10c; 10d) for access to the component accommodated in said compartment (7a; 7b; 7c; 7d; 7e); characterised in that said base half-shell (2a; 2b, 2c, 2d; 2d; 2e) and said covering half-shell (6a; 6b, 6c, 6d; 6e) both have side walls provided with half-openings (9a; 9b; 9c; 9d; 9d) for the passage of regions of the component to be connected to pipes or pipes to be connected to the component, said openings being then defined by the respective half-openings (9a; 9b; 9c; 9d) when coupling said half-shells together; a removable closure plate (11a; 11b; 11c; 11d) which can be positioned at said opening (10a; 10b; 10c; 10d) provided in the covering wall (8a; 8b; 8c; 8d), said closure plate (11a; 11b; 11c, 11d) having on its side designed to be directed toward said compartment (7a; 7b; 7c; 7d; 7e) at least one bar which can be coupled slidingly with a sliding seat defined in said locking element (5a; 5b; 5c, 5d; 5e), said locking element being associated by means of a screw element with a locking protrusion (14a; 14b; 14c; 14d; 14e) which protrudes from said base wall (3a; 3b, 3c, 3d; 3e), said art least one bar sliding also in said locking protrusion.