Staircases - Technique
Help with Solution-Finding
Our experience shows that in the case of spiral staircases it is often very difficult during the planning phase to find the location of the stairhead landing relative to the position of the first step. It is possible for the spiral staircase to be left or right-handed or to be produced with different circle graduations. The selection of the appropriate circle graduation depends on various factors. These can be the required minimum tread on the inner border in the case of spiral steps of 100 mm, the clear stair headroom of 2,000 mm, the pitch ratio of 2 s + a or the arrangement of the platforms.
The desired tread widths can be achieved for the diameters shown by means of various subdivisions. The following can be recommended as a fundamental rule: small diameter = fewer subdivisions and large diameter = more subdivisions.
Smaller stair diameters can only be used in situations where space is limited on the building site and in coordination with and with the approval of the local building supervisory authorities. For the non-public or private area it is possible to use smaller stair diameters.
The production range of the MEISER spiral staircases comprises a diameter from 1,200 to 4,000 mm and depends on the desired requirements as well as the structural conditions.
Clear Stair Headroom
"The clear stair headroom as a perpendicular finished dimension (where the stair is ready for use) is measured over an imaginary inclined plane which is formed by the front edges of the steps. The measurements are carried out from this plane or above the platforms to the undersides of the overlying components." This definition according to DIN 18065 has a significant influence on the construction of spiral staircases and is regrettably often neglected during the preliminary planning. We would therefore like to present this in the illustration, applied specifically to the spiral staircase. It is possible, for example, that a thicker concrete slab or lining of a platform structure will result in a reduction in the headroom.
Usable Stair Width
"The usable stair width as a clear finished dimension (measured when the staircase is ready to use) is measured horizontally between the limiting surfaces, components and/or inside edges of the hand rails or their projection". This is the definition of the usable stair widths according to DIN 18065. Our illustration is intended to provide a better explanation of the term "clear tread width" used by us in comparison to the usable tread width in the case of spiral staircases.
The selected examples of a spiral staircase show a stair diameter of approximately 2,900 mm with a usable width of approx. 1,000 mm, as well as the alternative solution for a stair diameter of approx. 2,300 mm with a clear tread width of 1,000 mm.
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