Construction system for single-layer space frames, comprising a generating surface formed by means of a structural assembly of hollow struts and nodes, wherein the nodes have a central axis perpendicular to the tangent plane of the generating surface, a side connecting surface, and connection means for connecting the end of each of the struts converging therein, and wherein: - the nodes are formed by a solid body, the side surface of which has connection planes for the connection to each of the struts converging in said node, respectively, wherein the connection means are arranged in each connection plane, each of said connection planes being perpendicular to the axis of the strut converging therein and having the same shape and dimensions as the section of said strut, and it comprises covering means for covering the connection means in each of the connection planes; - the covering means are formed by at least one overlapping cover formed by means of a portion of a strut having the same section as the strut that is connected to said plane, respectively, the depth of the overlapping cover being such that it is suitable for containing therein the part of the connection means arranged externally with respect to the strut and the node, wherein said overlapping cover has a first end (7.1) for being attached to the connection plane with a first laminar plate fixed thereto and an open opposite second end (7.2); - the connection means are formed by at least two threaded holes in each connection plane and screwing elements (5.1, 5.2) therein; and - the overlapping cover comprises passage means for the passage of the screwing elements (5.1, 5.2), formed by a first hole in the first laminar plate, close to a first side (12.1) thereof for the passage of a first screwing element (5.1), wherein said first hole is open towards a second side (12.2) of the first laminar plate, opposite the first side (12.1); the construction system being characterized in that the overlapping cover has a portion of one side thereof that is open, said side being opposite the side close to the first screwing element (5.1). - the nodes are formed by a solid body, the side surface of which has connection planes for the connection to each of the struts converging in said node, respectively, wherein the connection means are arranged in each connection plane, each of said connection planes being perpendicular to the axis of the strut converging therein and having the same shape and dimensions as the section of said strut, and it comprises covering means for covering the connection means in each of the connection planes; - the covering means are formed by at least one overlapping cover formed by means of a portion of a strut having the same section as the strut that is connected to said plane, respectively, the depth of the overlapping cover being such that it is suitable for containing therein the part of the connection means arranged externally with respect to the strut and the node, wherein said overlapping cover has a first end (7.1) for being attached to the connection plane with a first laminar plate fixed thereto and an open opposite second end (7.2); - the connection means are formed by at least two threaded holes in each connection plane and screwing elements (5.1, 5.2) therein; and - the overlapping cover comprises passage means for the passage of the screwing elements (5.1, 5.2), formed by a first hole in the first laminar plate, close to a first side (12.1) thereof for the passage of a first screwing element (5.1), wherein said first hole is open towards a second side (12.2) of the first laminar plate, opposite the first side (12.1);