What Is Staircase?
The room or enclosure of the building, in which the staircase is located, is known as a staircase. The opening or space occupied by the stairs is known as the staircase.
In a domestic building, the stairs must be centrally located to facilitate access to all rooms. In public buildings, the stairs must be located close to the entrance.
Stairs can be built with wood, bricks, stone, steel or reinforced concrete. Stairs provide access and communication between floors of multi-story buildings and are a pathway through which fire can spread from floor to floor.
Therefore, the staircase must be surrounded by walls, floors, roof, and fire-resistant doors. It is desirable that the wall and ceiling coverings are non-combustible and with the low flame spread.
Another important aspect in the design of stairs is the aspect of strength. It must be designed to carry certain loads, similar to those used for floor design.
Also, read: Type of Stair | Stairs Parts Names & Details
What Is Dog-Legged Staircase?
It is also called Dog Legged Staircase, because of its appearance in sectional elevation.
It is a very common and popular type of staircase and is used in public and residential buildings. It consists of two flights that run in opposite directions, separated by a landing in the middle space or a quarter in space and a set of rollers.
The dog-legged stair is so named because the slope of the staircase is similar to the dog’s leg. When the available space is equal to twice the width of the stairs, the dog-legged staircase is used.
From the design point of view, the advantage of this staircase lies in its compact layout and better circulation.
Therefore, it finds application in almost all types of buildings, whether residential, commercial or institutional. It is common to find sketching such a staircase in architectural projects.
But such a simple staircase does not result in a smooth handrail, which is one of the essential components of any staircase.
Handrails are provided to provide assistance and protection and must be fixed at a convenient height from ground level. They must be of satisfactory size and shape to allow them to be easily grasped by the hand.
Details of Dog-Legged Staircase
The stairs are made up of individual steps. Each step consists of a tread and a riser. The floor is the flat part you step on. The riser is the vertical part (up and down) between each step of the stair. step and riser
Dog-Legged Staircase is the most economical staircase. These stairs are arranged with two adjacent flights, parallel to an average landing. Where space is less, a dog-legged staircase
usually provided, resulting in economical use of the available space. In this type of staircase, the landing is provided according to the level at which the direction of the flight changes.
Requirements for Good Stairs
Any well-planned stairs must meet the following criteria for an easy, fast, and safe ascent/descent.
Location: must be located in order to obtain sufficient lighting and ventilation, with easy access from all rooms.
Length of flight: a flight should have no less than three risers and no more than 16 risers.
Pitch of stairs: the stairs are inclined (stair angle) from 15 to 55 degrees; however, the recommended angle is between 25 to 40 degrees. Long stride should be flattened using landings.
Landing: in any case, the width of the landing must not be less than the width of the flight of stairs.
Step Proportions: the rise/rise of each stage on a flight and on flights and landings between floors must be the same. Any variations can ruin the pace. The climb/climb is provided to ensure comfortable access.
Dog-Legged Staircase (Half Turn and Quarter Turn)
This type of staircase consists of two flights parallel to each other. The flights of stairs run in opposite directions and have little or no space between their balustrades.
Sometimes the two flights of stairs can be on the adjacent walls, forming a quarter-turn staircase.
Advantages of Dog-Legged Staircase
- Efficient use of space: This type of staircase covers much less area than straight They allow for a more compact stair arrangement.
- Privacy: These stairs are great if you want to separate one floor from another for any reason. As the top floor cannot be seen and vice versa, these stairs offer ample privacy to users.
Disadvantages of Dog-Legged Staircase
- Difficult to build: These stairs are not very easy to build.
- Handrails on these stairs also need careful planning.
Example: Dog-Legged Staircase Design
Designing a Dog-legged staircase for a residential building, where the space provided is 2.5mx 4.5m and the floor to floor height is 3.3m
Generally, for residential buildings, we adopt Rise and the pitch of each step is 150 mm and 225 mm.
1 = 2.5m x 4.5m
Floor height = 3.3m
Total number of flights = 2.
So, flight height = 3.3 / 2 = 1.65m
Elevation = 150mm, Floor = 225mm
No. of risers = 1650/150 = 11
Therefore, number of steps = 11-1 = 10
Adopting stair width = 1.2m
For 10 steps, the required length = 10 x0.0225 = 2.25m
Landing width = (4.5-2.25)/2 = 1.125m