Characteristics of a Good Staircase
A good staircase should have the following characteristics.
·
It should have sufficient size. It should not be too large or too small.
·
The step of the stair should be sufficiently wide.
·
The stairs should be solid and durable.
·
The riser should not be higher than 20cm.
·
The inclination should not be less than 25o and not exceed 45o.
·
A flight of stairs should have a minimum of 3 steps not exceeding 15
steps.
·
It should have a sufficient landing area.
·
It must have handrails.
·
It should be easily accessible from all rooms of the building. It should
be centrally located in residential buildings and at the entrance of public
buildings.
Types of Staircases
Staircases are classified into different types
depending on the type of tread and landings provided. The landing style and the
type of tread to be used depend on the vertical distance between the two floors
and the space available for the staircase.
1.
Straight staircase
Stair may have one flight or two
flights with a landing. These are normally open-type stairs with one side open
and are space constraints. This type of staircase is preferred for small or
domestic buildings. Straight stairs can be made of concrete, stone, wood, steel,
or a combination of any of these. Fig 2 below shows a straight staircase.
2. Dog legged Staircase
A Staircase to which newel posts are provided at the beginning and end of each flight is known as a Dog legged staircase. There is no space between two flights. A half-spaced landing is provided generally that affects the change in direction. Fig. 1 shows a doglegged staircase.
1.
Quarter turn Staircase
A stair turning through one right angle
i.e., 90o is known as quarter turn stairs. These are also known as
Newel Quarter turn staircase. The change in direction can be affected by either
introducing a landing or by providing winders. The stairs rise to a landing
between two floors, turn through 90, then rise to the floor above. This type of
staircase is often used in two-floor semi-detached houses.
2.
Open Newel Stair
This type of staircase has a well or
opening between the flights in a plan. The well may be rectangular or of any
geometrical shape and can be used for fixing lift. Fig.4 shows an illustrated
example of an open newel staircase.
3.
Three quarter turn stairs
The staircase where the direction of
the flight is changed by 3 times in 90o or quarters is known as
three quarter turn stairs. This type of stair is preferred when the length and
breadth of the stair room are limited and the vertical distance between two
floors is quite large. Fig.5 represents the plan of three-quarter turn stairs.
4.
Bifurcated Staircase
If a quarter-turn stair is branched
into two flights at a landing, such a staircase is known as a Bifurcated staircase.
This type of stair is commonly used in public buildings near the entrance hall.
The stair has a wider flight at the bottom which bifurcates into two narrower
flights at the landing. One turns into the left and the other to the right. These
staircases may or may not have equal flights. Fig.6 represents the plan of a
bifurcated staircase.
1. Geometrical staircase
This type of stairs has a geometrical
shape and does not require a newel post. This type of stair is similar to open
newel stair except the well-formed between forward and backward flight is
curved. Change of direction in such stairs is achieved by winders and not by
landings. Figure 7. a shows the elevation and fig 7. b shows the plan of a
geometrical staircase.
2.
Circular staircase
These are also known as spine wall
stairs. They consist of a central vertical wall from which the flights and half-space
landings are cantilevered. All the steps in the circular staircase are winders.
This type of stair is provided where space is limited and traffic is casual.
These are mostly located at the rear of the building. Figure 8 represents a circular
staircase.
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