Stair Design & Construction: “A Stair is a system of steps by which people and objects may pass from one level of a building to another.”
A stair is to be designed to span a large vertical distance by dividing it into smaller vertical distances, called steps.
Stair Design & Construction
Some of the functional requirements of staircases are;
- Stability
- protection from fire
- Suitable dimensions (for normal, elderly, disabled people & children)
- appearance
COMPONENTS & TERMINOLOGY
- flight: A series of steps between different levels or storeys of a building
- landing: An area of floor at the top of or between flights of stairs for changing direction in the stairs & providing a resting place between long flights of stairs.
- tread – The part of the step that is stepped on.
- riser – The vertical portion of the step between steps.
- nosing – An edge part of the tread that extends from the riser beneath.
- winders – Winders are steps that are narrower on one side than the other. They are used to change the direction of the stairs without landings. A series of winders form a circular or spiral stairway.
- stringer or string – The structural member that supports the treads. There are typically two stringers, one on either side of the stairs; though the treads may be supported many other ways. The stringers are notched so that the risers and treads fit into them.
- handrail: A rail fixed parallel above the pitch line at the sides of a stair.
- balusters: Vertical members which support a handrail.
- Newel: A vertical post which might provide support for either the handrail, or support for the upper end of an outer string.
- bullnose – when one or both sides of the stairs are open, the first step above the lower floor may be wider than the other steps. The rounded portion of the step is called a “bullnose”.
SUITABLE DIMENSIONS FOR STAIRCASES
•Riser and tread; in a flight of stairs all steps should have the same riser and same tread.
•Relationship between riser and tread can be shown as 2R+T=63cm
•Convention centers, cinema,Theaters: R=16cm
•Schools, hospitals, Office buildings R= 17cm
•Residential Buildings R=18cm
•Steepness of stairs; Regular pitch: 25-36 °
Types of Staircases (Plan types)
• Straight run
• 180 degree return
• L shaped
• Spiral
Straight Run Stairs
Cable rails | Stair Design
Cable railing requires very rigid frames compared to many other types of railings due to the forces applied to the end posts by tensioning the cables. Cables must be tensioned to provide a rigid as possible condition to satisfy building code requirements. Common frame types are constructed of steel, stainless steel, extruded aluminum or wood.
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