Abstract: A support for treads of a staircase is formed by a plurality of support elements each comprising an upper plate and a lower plate, the lower and upper plates of each element being adapted to rest on the upper and lower plates respectively of contiguous elements. Adjustment and fixing members enable the upper plate to be moved relative to the lower plate of each element and be fixed together. The upper plate of each element is formed with at least one pair of holes, and at least one pair of female threads is fixed to the plate, each thread being coaxial with one of the holes. The lower plate of each element is formed with a through-hole and through-slot into which are inserted two screw members, each of which also passes through one of the holes in the upper plate of the contiguous element and is screwed into the corresponding female thread in the contiguous element so as to fix these two elements together.

Abstract: The modular support for staircase steps comprises a substantially vertical box-like body upwardly defining a horizontal base plane for a related step, a male cylindrical element and a complementarily shaped female cylindrical element extending vertically at two different levels at the opposite longitudinal ends of said box-like body and adapted to be coupled in an angularly adjustable position to corresponding cylindrical elements of adjacent supports, said male cylindrical element being less extended vertically with respect to said female cylindrical element so as to allow an adjustment of the mutual axial position by means of the insertion of suitable spacer means, substantially axial means along finally provided for the locking of said coupled cylindrical elements.

Abstract: The support comprises a horizontal resting deck for a respective step. A first wall including a vertical cylindrical portion is made rigid, on the convex side thereof, with said resting deck and extends above the latter. An additional wall including a vertical cylindrical portion extends fixedly below the resting deck with its concave side facing the convex side of the first wall. Said additional wall has an outer surface matching the outer surface of the first wall.