Among the early materials used for external staircases, stone slabs were the most popular
What is a staircase in its basic and essential form? How did early humans negotiate heights? What are the methods of constructing steps judiciously with least resources and money? What are the maintenance costs of stairs? We are raising these questions not only to define a staircase, but also to be able to design one appropriately and eco-friendly.
Even before people had to climb up to the first floor of a building, they had to climb down to an open well or to a water canal. Walking down the slope of a river bank, carving horizontal levels down to a water tank, digging wells with steps leading to the bottom and such others were among the early explorations in the act of climbing up or down. Climbing up a tree would also have taught the humans to seek a firm and horizontal level beneath the feet. This level, called as tread, and the height to the next tread, called as riser, together form a step. The series of steps is termed as staircase.
Among the early materials used for external staircases, stone slabs were arguably the most popular. A casual trip down to most Indian villages will showcase slabs jetting out of the external wall of the house, going up to the terrace.
With no member in the riser part, this void would let in light, minimise material usage and make the whole assemblage of the steps comparatively easy. Possibly, the inspiration for such stairs might have come from the steps leading down into an open water well, a method with continued application.
Wall and slabs
As the wall is being built, at the pre-marked locations, the stone slab is inserted into the wall, with temporary support at the other projected end. Once the main wall rises, its weight pins down the tread and the temporary end support can be removed.
The thicker the wall, the better for stability. In case the wall is only around 9” thick, the stone slab needs to project out on the other side of the wall at least by 6”, to provide the necessary strength.
If the illustration makes us feel that the tread and risers could be of any size, we are wrong. There are scientific rules that suggest staircase dimensions. The height to which we can lift our feet up and there upon, the forward distance possible is governed by our body measures called anthropometrics and limb movements. Generally, 12” wide tread and 6” high riser has been accepted as the design norm, but this can vary slightly.
In principle, the higher the riser, say 7”, the narrower the tread has to be, say 11” wide. Despite all the talk about standards and measures, humans are uniquely blessed. We can climb up a tree which is like a vertical pole and also climb up a hill which is like the expansive inclined earth!