Stairs – Terms, Requirements, Planning, Designing and Construction Details
Stairs are essential components of a building that provide access between different floors. In ITI Draughtsman Civil, knowledge of stair terminology, design principles, and construction details is important for preparing accurate building drawings and ensuring safe movement of people.
1. Definition of Stair
A stair is a series of steps arranged to connect different levels of a building. It provides vertical circulation and is commonly used in residential, commercial, and public buildings.
2. Technical Terms Related to Stairs
- Tread: The horizontal top surface of a step on which a person places the foot.
- Riser: The vertical face of a step.
- Flight: A continuous series of steps without a break.
- Landing: A flat platform provided at the end of a flight.
- Nosing: The projecting edge of the tread beyond the riser.
- String: The inclined member supporting the steps.
- Handrail: A rail provided for support while ascending or descending.
- Baluster: Vertical members supporting the handrail.
- Newel Post: A vertical post at the ends of stairs supporting the handrail.
- Pitch: The angle of inclination of the stair.
- Headroom: The vertical distance between the tread and the ceiling above.
- Width of Stair: The clear width available for movement.
3. Requirements of a Good Stair
- Should be strong and durable.
- Provide safe and comfortable movement.
- Proper width for easy passage of people.
- Uniform size of treads and risers.
- Proper lighting and ventilation.
- Non-slippery surface.
- Proper handrails for safety.
4. Planning of Stairs
Planning of stairs involves deciding the location, type, and dimensions of the stair in a building. Proper planning ensures efficient use of space and safe movement.
Points to Consider in Planning
- Location should be easily accessible.
- Should not obstruct natural light and ventilation.
- Should connect all floors conveniently.
- Provide sufficient headroom (generally not less than 2.1 m).
- Number of steps and flights should be properly calculated.
5. Designing of Stairs
Designing of stairs involves determining the size and proportion of steps to ensure comfort and safety.
Important Design Factors
- Riser Height: Usually between 150 mm to 190 mm.
- Tread Width: Usually between 250 mm to 300 mm.
- Proportion Rule: 2 × Riser + Tread = 600 mm to 650 mm.
- Width of Stair: Depends on type of building (generally 1 m or more).
- Pitch: Should be between 25° to 40°.
Types of Stairs (Based on Design)
- Straight Stair: Single straight flight.
- Quarter Turn Stair: Changes direction by 90°.
- Half Turn Stair: Changes direction by 180°.
- Spiral Stair: Circular stair around a central post.
- Circular Stair: Curved without central support.
6. Details of Construction of Stairs
Stairs can be constructed using different materials such as timber, steel, and reinforced cement concrete (RCC). RCC stairs are most commonly used in modern construction.
Steps in Construction of RCC Stair
- Prepare detailed drawings showing dimensions and reinforcement.
- Construct formwork (shuttering) for steps and landings.
- Place steel reinforcement as per design.
- Pour concrete into the formwork.
- Compact and level the concrete properly.
- Allow curing for sufficient time.
- Remove formwork after setting.
- Provide finishing such as tiles or stone.
Materials Used in Stair Construction
- Concrete and steel (RCC stairs)
- Timber (wooden stairs)
- Steel sections (industrial stairs)
- Stone or marble (for finishing)
7. Safety Considerations
- Provide non-slip treads.
- Ensure proper lighting.
- Install handrails at suitable height.
- Avoid uneven steps.
- Maintain sufficient headroom.
Role of Draughtsman Civil
A Draughtsman Civil prepares detailed stair drawings including plan, elevation, and section. These drawings show dimensions, reinforcement details, and materials used. Accurate drawings help in proper construction and safety of stairs.
Conclusion
Stairs are important structural elements that ensure vertical movement in a building. Proper understanding of stair terms, requirements, planning, designing, and construction is essential for safe and efficient building design.
For ITI Draughtsman Civil students, mastering stair design and construction helps in creating accurate and practical building drawings.