Staircase - Dimensions of Stair Steps and their Deviations of Geometrical Accuracy

Abstract

The staircase is an integral part of most buildings. It is subject to the same technological principles and constraints as for other building structures. This design must meet basic technical requirements, including stairway safety. The requirements for selected geometric parameters of stair steps are defined in Czech technical standards and regulations. Generally, the requirements of these regulations are summarized as follows: "All the stairs to the walking line in one flight must have the same height and width and must be horizontal, without inclination in the transverse or longitudinal direction." This provision prescribes mainly design requirements of stairs, while the requirements for as-built stairs are not taken into account. This is evidenced by the fact that in the Czech technical regulations and standards the geometrical accuracy of the as-built stair steps is not specified. Deviations from the geometrical accuracy of stair steps are technologically inevitable. But in practice in the Czech Republic, we encounter situations where builders use the formulation of technical standards and binding regulations to their advantage and refuse to take over the completed staircase. As an argument, they use the formula stated in the above-mentioned regulations. Based on this wording, they require the completed stair steps to have zero geometric accuracy deviations, which are technologically unfeasible. The only way to prevent these attempts is to revise existing regulations to complement the design requirements, including allowable deviations of the geometric accuracy of stair steps. Geometrical tolerances must be determined to take account of the technological possibilities of the construction and to assure safe movement on the staircase. Measurements of dimensions (rise and going) of the as-built stair steps (rise and going) were executed. The results of the measurements were compared with the requirements of the British and German technical standards for staircases. Measurements made in buildings in the Czech Republic showed that about 95% of the measured deviations of step rise and going were not more than 5 mm, which complied with the requirements of the German technical standard.