A structural element system for the construction industry has post sections, framed flat elements, holding sections, and seals, wherein, for thermal insulation of the post sections and the framed flat elements, the holding sections are attached on the post sections, wherein the framed flat elements are attached to the holding sections, and wherein the seals together with the post sections form chambers. In the mounted state of the structural element system, the holding sections are enclosed in the chambers. The post section is a box section having at least one rectangular box for securing the holding sections, respectively, wherein the rectangular box has on two parallel outer sides at least two holding lips for securing the holding sections or a connecting member. The system can be used to erect curtain facades, facade linings, transparent roofs, sunrooms, soundproofing walls, fair buildings, carports and the like.