Dog-legged staircases are a popular choice in residential and commercial buildings due to their space-efficient design and aesthetic appeal. Named for their resemblance to the bent hind leg of a dog, these staircases consist of two flights running in opposite directions with a landing in between. This guide will explore the design of dog legged staircase, structural considerations, and construction process.
Introduction to Dog-Legged Staircases
What is a Dog-Legged Staircase?
A dog-legged staircase features two flights of stairs separated by a landing, with both flights running in opposite directions. This type of staircase is particularly efficient in terms of space utilisation, making it ideal for buildings with limited area.
Advantages of Dog-Legged Staircases
- Space Efficiency: The design allows for a compact staircase that fits well into small spaces.
- Aesthetic Appeal: The opposing flights and intermediate landing create a visually appealing structure.
- Functionality: Provides a convenient break in the staircase, making it easier to navigate, especially in multi-story buildings.
Design Considerations
Space and Layout
Before proceeding to design of dog legged staircase, it’s crucial to assess the available space and layout of the building. The following factors should be considered:
1. Staircase Width: The width of the staircase should accommodate comfortable passage. Typically, residential staircases have a width of 900 mm to 1000 mm, while commercial staircases may be wider.
2. Rise and Tread Dimensions: The rise (vertical height of each step) and tread (horizontal depth of each step) should comply with building codes. A common rise is around 150 mm to 180 mm, and the tread is typically 250 mm to 300 mm.
3. Landing Dimensions: The landing should be at least as wide as the staircase and long enough to provide a safe transition between flights. A minimum length of 900 mm is recommended.
4. Headroom: Ensure sufficient headroom (at least 2 meters) above each step and landing to prevent head injuries.
Structural Considerations
The structural integrity of the staircase is paramount. Key structural elements include:
1. Stringers: These are the inclined beams that support the steps. Stringers can be positioned on the sides (closed stringers) or underneath the steps (open stringers).
2. Steps: The steps consist of the riser (vertical part) and tread (horizontal part). Both should be securely attached to the stringers.
3. Landing Support: The landing must be adequately supported by beams or walls to ensure stability.
4. Handrails and Balustrades: These provide safety and support. Handrails should be comfortable to grip, and balustrades should be spaced to prevent falls.
Design Calculations
Accurate calculations are essential to ensure the design of dog legged staircase is functional and safe. The following steps outline the basic calculations:
1. Total Rise: Measure the total height from the finished floor of the lower level to the finished floor of the upper level.
2. Number of Risers: Divide the total rise by the desired height of each riser. Round to the nearest whole number.
3. Riser Height: Divide the total rise by the number of risers to get the exact height of each riser.
4. Number of Treads: The number of treads is one less than the number of risers.
5. Staircase Length: Multiply the number of treads by the tread depth to find the total length of the staircase.
Example Calculation
Let’s assume the following parameters:
- Total rise = 3000 mm
- Desired riser height = 160 mm
- Desired tread depth = 270 mm
Step 1: Calculate Number of Risers Number of risers = Total rise / Riser height = 3000 mm / 160 mm = 18.75 (rounded to 19)
Step 2: Calculate Exact Riser Height Exact riser height = Total rise / Number of risers = 3000 mm / 19 = 157.9 mm
Step 3: Calculate Number of Treads Number of treads = Number of risers – 1 = 19 – 1 = 18
Step 4: Calculate Staircase Length Staircase length = Number of treads * Tread depth = 18 * 270 mm = 4860 mm
Construction Process
Materials and Tools
- Materials: Timber or steel for stringers, risers, and treads; concrete for the landing; handrails and balustrades.
- Tools: Measuring tape, saw, drill, level, hammer, nails or screws, concrete mixer (if using concrete).
Step-by-Step Construction
1. Planning and Layout: Mark the staircase layout on the floor and walls. Ensure accurate measurements and alignments.
2. Prepare the Stringers: Cut the stringers to the calculated dimensions, including notches for risers and treads.
3. Install the Stringers: Secure the stringers to the floor and wall using brackets or bolts.
4. Construct the Landing: Build the landing framework using timber or steel, and pour concrete if required. Ensure it is level and well-supported.
5. Attach the Steps: Fix the risers and treads to the stringers, starting from the bottom. Ensure each step is level and securely attached.
6. Install Handrails and Balustrades: Attach handrails to the stringers and secure balustrades at regular intervals.
7. Finishing Touches: Sand and finish the steps, stringers, and handrails. Apply paint or varnish as needed.
Safety Considerations
- Non-Slip Surfaces: Use non-slip materials for treads to prevent accidents.
- Lighting: Ensure the staircase is well-lit to avoid trips and falls.
- Regular Maintenance: Inspect the staircase periodically for any signs of wear or damage and repair as needed.
Conclusion
Construction and design of dog legged staircase require careful planning, precise calculations, and attention to detail. By following the guidelines outlined in this guide, you can create a functional, aesthetically pleasing, and safe staircase that optimises space and enhances the overall design of the building. Whether for a residential or commercial project, a well-designed dog-legged staircase can add significant value and appeal to any property.
Frequently Asked QuestionsÂ
Q: What is a dog-legged staircase?
A: A dog-legged staircase is a type of staircase that features one or more landings where the direction of the stair flight changes. It is typically used in spaces with limited floor area to provide a more compact staircase design.
Q: What are the main advantages of a dog-legged staircase?
A: The primary advantages of a dog-legged staircase include space-saving, increased safety due to multiple landings, and the ability to accommodate different floor levels or split-level designs.
Q: What are the different types of dog-legged staircases?
A: Common types of dog-legged staircases include quarter-turn, half-turn, and open-newel dog-legged staircases.
Q: What is the minimum recommended width for a dog-legged staircase?
A: The minimum recommended width for a dog-legged staircase is typically 900mm (36 inches), although building codes may vary.
Q: What is the maximum recommended rise and going for dog-legged stair treads?
A: The maximum recommended rise (vertical height) is typically 190mm (7.5 inches), and the minimum going (horizontal depth) is typically 250mm (10 inches), although building codes may vary.
Q: How do you calculate the number of treads and risers required for a dog-legged staircase?
A: The number of treads and risers is calculated based on the total vertical height of the staircase and the desired rise and going dimensions for each tread and riser.
Q: Can dog-legged staircases be made with different materials?
A: Yes, dog-legged staircases can be constructed using various materials such as wood, steel, concrete, or a combination of materials.