Section of stairs of 6 story building.

This Architectural Drawing is Section of stairs of 6 story building. According to the Indian National Building Code, the minimum space for staircase in terms of width in a normal residential building should be 3 feet and 6 inches, minimum width of tread without nosing should be 10 inches and if nosing is required, it should be 10 ¼ inches. The typical interior stair dimension is calculated as the formula, riser (R)+ tread (T) = 17 inches minimum, or 18 inches maximum, not including the nosing. The nosing is the projecting edge of a tread. Rule one says that rise plus run (r+R) should equal 18 inches. Why? That's what most people find to be a comfortable stride on most stairs. You can cheat a bit up or down, but below 17” and more than 19” will result in steps that require strides either too big or too small for most people. For more details and information download the drawing file.