A knob couplable by screwing, to a spacer-leveler of tiles for together defining a tile alignment device for laying the tiles on flat surfaces, the spacer-leveler comprising:
- a rest wall which is planar and which has a relative respective upper surface;
- a separator member which originates from the upper surface of the rest wall, which extends for a respective height, and which comprises a plurality of lateral abutment surfaces;
- a threaded rod perpendicular to the rest wall which originates from the separator member;
- wherein the separator member is connected to the rest wall or the threaded rod by a respective end of section able to function as a snap-off section, the knob comprising:
- a respective body having at a respective first side, a terminal surface arranged along a plane;
- first and second connection means which originate from the body of the knob;
- a first and a second fixing element, each of which comprises a respective threaded slot with a threading that is complementary to the threading of the threaded rod of the spacer-leveler and arranged perpendicularly to the plane, the first and second fixing elements being stably supported respectively by the first and second connection means in:
- a first respective arrangement in which respective threaded slots are facing one towards the other at a first distance so that the threaded rod of said spacer-leveler can be inserted in and extracted from between the threaded slots without having to be screwed in or unscrewed;
- or in a second arrangement in which the respective threaded slots are facing one towards the other and arranged in such a way that the insertion in or extraction of the threaded rod from the threaded slots can take place only by screwing or unscrewing, wherein at least one from between the first and second connection means is elastically deformable, so as to enable the first and second fixing elements to change the arrangement thereof from the first to the second arrangement and vice versa;
- a blocking element, separated from the body of the knob and removably couplable to the first and second fixing elements or to the first and second connection means so as to elastically deform at least one from between the first and second connection means so as to change the arrangement of the first and second fixing elements from the first arrangement to the second arrangement, and vice versa, in order, when the terminal regions of at least two tiles are resting on the unoccupied portions of the upper surface of the rest wall of the spacer-leveler with the respective lateral edges in contact with the plurality of abutment surfaces, to be able to insert, from the first side of the knob, the threaded rod between the threaded slots of the first and second fixing means in the respective first arrangement without screwing the threaded rod, and to be able, with the threaded rod inserted, to arrange the first and second fixing elements in the respective second arrangement and screw the knob to the threaded rod so as to align the tiles between the upper surface of the rest wall and the terminal surface along a same plane, and to be able, with the knob screwed on, to arrange the first and second fixing elements in the respective first arrangement with the aim of being able to extract the threaded rod from the two threaded slots without unscrewing the threaded rod, once the snap-off section of the spacer-leveler has been fractured.