What Is Dog Legged Staircase
A dog legged staircase consists of two flights running opposite to each other with a landing at the point where the direction of flight is changed. It is the simplest form of the staircase after the straight staircase and it is widely adopted too.
The construction of the Dogleg Stairs is economical because of its compact design. The staircase utilizes the space provided. It just requires space that is twice the width of steps.
Fact behind its Name,
A Dog Leg Stairs looks like a dog in elevation. The slope of the staircase is similar to the angle between the legs of a dog.
That is why it is named the dog legged staircase.
Is the Length of Flight Equal?
No, the length of both the flights is not needed to be equal. In most of the cases, it is kept unequal.
This staircase is provided in residential, commercial, institutional, and public buildings.
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Components of Dog Legged Staircase
The components of a dog legged staircase are as follows:
- Tread: The portion of the staircase on which the foot is stepped on is called tread.
- Riser: The part of the staircase between two treads is called a riser.
- Newel post: The vertical post at the start and end of the flight is called a newel post.
- Baluster: The vertical support installed throughout the length of a flight on which a handrail is supported to prevent the fall is called a baluster.
- Handrail: An inclined rail provided at an optimum height so that it can support the person while ascent or descent is called a handrail.
- Landing: A platform provided to break the continuity of flight for providing rest to the user is called landing.
- Pitch: The angle the line of nosing makes with horizontal is called pitch.
- Line of nosing: An imaginary line parallel to the slope of the staircase that joins the nosing of the staircase is called the line of going.
Suitability of Dog Legged Staircase
When much space is not available, the dog legged staircase is most suitable. The space required for the doglegged staircase is equal to twice the width of the treads.
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Advantages of Dog-Legged Staircase
- The design of the staircase is quite simple.
- Drafting of the staircase is also easy and faster too.
- Space is efficiently utilised reducing space wastage and more carpet area is available for usage.
- The privacy of the floors is maintained in this type of stairs as the top floor is not visible from below nor bottom floor is visible from the top.
- Architectural effects can be easily infused in this type of staircase.
- The landing provides a resting space so that commuting becomes easier.
Disadvantages of Dog-Legged Staircase
- The construction of the dog legged staircase is quite difficult.
- The provision of handrails is to be planned carefully as it is quite difficult to install.
- Handrails are an important part of a staircase that supports the ascent and descent.
- The movement of heavy items through the staircase is a bit difficult.
How a handrail cannot be provided smoothly in case of a dog legged staircase is shown in the below figures.
Design of Dog Legged Staircase
Some of the criteria to be kept in mind while designing a dog legged staircase are discussed below:
- It should be located in a central position in the room so that staircase is easily accessible from all parts of the floor.
- Lighting and ventilation should be maintained on the staircase.
- Flight Length:
- Minimum 3 risers are to be provided on a flight.
- In addition, a flight should not have more than 16 risers for comfortable traversing through the staircase. A landing is to be provided to break the continuity.
- Pitch or Slope:
- The recommended slope of a staircase is between 25-40°C.
- However, the slope should not be kept less than 15° C.
- If the slope exceeds 55 °C, it would be too steep to transverse.
- The width of the landing should not be less than the width of the tread in the flight.
- Step Ratio:
- Rise to going ratio of both the flights of the staircase should be kept the same.
- If there is a difference in the ratio, the rhythm will be spoiled and the person traversing through the staircase would feel uncomfortable.
Dog-Legged Staircase Design Example
Design a dog-legged staircase for a residential building. The space available for the stairwell is 2.5 * 4 m. The floor-to-floor height is provided at 3.1 m.
- For residential a building, normally the riser height is taken from 150-190 mm.
- So, let us provide the riser of a height of 160 mm.
- Also, tread depth is taken as 225 mm.
- Stairwell dimensions = 2500 * 4000 mm
- Floor height = 3100 mm
- Total number of flight to be provided = 2
Therefore, height of 1 flight = 3100/2 = 1550 mm
- Rise = 160 mm
Therefore, Number of risers in a flight = 1550/160 = 9.6 Say 10 risers
- Number of treads = Number of riser – 1 = 10 – 1 = 9
- Let Tread width = 1.2 m
- Length for 9 treads = 9 * 0.0225 = 0.2025 mm = 2.025 m.
- Width of landing = (4 – 2.025)/2 = 0.9875 m which is approximately 1.0 m
The number of risers in a flight = 10
Landing width = 1 metre
Dog Leg Stair Calculator
|Type of stair||Dog legged|
|Assumed height of the riser||160 mm|
|Assumed depth of tread||225 mm|
|Number of flight||2|
|Height of floor||3100|
|Number of riser||(3100/2) /160 = 10 Riser|
|Number of treads||R-1 =9|
|Width of Landing||No. of tread * depth of tread = 9 * 225 = 1000|
Dog legged staircase is one of the simplest forms of the staircase in which a landing is provided between two flights that meet at 180 degrees.
It makes economic use of the space and normally, the length of its flights is kept unequal.
The pitch angle is similar to the angle between a dog’s legs, therefore, it is known as the dog leg stairs.
Its design is pretty simple and at the same time, it provides privacy on both floors. Moreover, architectural effects can be easily included in this type of staircase.
However, construction is challenging and the handrail provision is difficult too.
Above all, dogleg stairs are most widely used for their compact design.
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