Material Classification of Stairs

In earlier days, timber stairs were widely used, but with the advent of concrete construction, stairs are now mostly made of reinforced cement concrete. 

In wooden stairs, the treads are made of abrasion resistant wood such as oak, teak, etc. while the risers could be of softer wood like deodar, pine, etc. The thickness of the tread is generally, 30 to 32 mm and that of the risers 25 mm. The tread and riser are connected by a tongue and groove joint, and also screwed or nailed together. 

The treads and risers are supported on one or more stringer beams (also known as carriages). Upper edges of these beams are cut to receive the risers and treads. Stringers are supported on transverse beams known as headers.

  Various types of Stairs 

For stone stairs, the stones should be durable and weather resistant. Being heavy in weight, they require adequate supports and are not commonly used except for monumental buildings or for front entrances of public buildings. 

Steel stairs can be made of risers, and treads of cold fonned steel or floor plates. These are supported at the ends by carrier angles which in turn are fastened to inclined stringers. Their use is generally restricted to factories, godowns etc. 

Nowadays most of the stairs are built of RCC having following advantages : 

Concrete can be moulded to the required form; it has fue resistant qualities; it can be designed to suit the given width and span; and requires hardly any maintenance. As RCC can be cast at site, unlike other materials, it is easy to adjust the heights of risers and widths of treads to the actual dimensions of the staircase as may have already been constructed. These stairs are generally designed as slabs spanning between beams. They can also be designed as cantilevered steps. 

Escalators 

In public buildings where there is a large valume of pedestrian movement between floors, moving stairs, which are powered by electric motors, are provided and these are called escalators. 

Lifts 

For speedy vertical movement particularly in tall buildings, having many floors, lifts are used. These are provided in shafts and are generally operated by machinery run on electricity provided at the top, above the last floor to which access is to be provided. There are openings in the shaft onto each floor level with automatically operated doors which open and close along with the lift car doors.