A steel support profile for support structures for facades or conservatories, in which a receiving channel for receiving mounting screws for the fixation of retaining profiles is formed by an outward-facing side wall of the steel support profile, and a support structure for facades and conservatories with a steel support profile, on which at least one facade element is fixed by a retaining profile fixed by mounting screws on the steel support profile in a sealed manner via inner and outer seals. An easily producible steel support profile and a support structure that allow greater opportunities for design, by a steel support profile in which the side wall is welded to a base profile, and a support structure with such a steel support profile.