Staircase I. Narrow, with flat bottom through the centre.
This staircase is named after its load bearing structure. It is the staircase most suitable for exploitation as the stairs are independent of the surrounding area. This structure is anchored to the foundation and to the floor ceiling. The distance from the surrounding area (walls) is 3-5 cm, or the wall space can be separated by handrails. The 3-5 cm intervals from the ends of the treads ensure the clean surrounding walls during the exploitation and cleaning of staircase. Prerequisites necessary for this structure include ferroconcrete base and ferroconcrete floor. However, solid wood floorings are suitable as well, especially when the edges of flooring are covered with metal profiles of the specified size, depending on the size of the structure and its own weight, leaving the possibility of adapting this staircase in wooden buildings with wooden flooring. However, concrete basis for this construction is a must.