# Stairs

Stairs. Constructive element formed by a series of steps arranged in an inclined plane to go up and down between the different floors or levels. In the buildings, the stairs must allow secure, comfortable and small space communication, between premises located at different levels; for example: between the ground floor and the basement or the upper floors.

Summary

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• 1 Parts of a ladder
• 2 Classification of the stairs
• 3 Drawing a straight ladder
• 1 Example
• 2 Solution
• 6 Sources

The following parts are distinguished in every staircase:

• Paw print.
• Riser
• Railing or railing.

Classification of the stairs

The stairs can be classified according to the situation, shape and manufacturing material:

1. a) By location
• Outside: Basement stairs and stairways
• Interiors
1. b) By the way:
• Straight (of one or several sections)
• Curves
• Scissors
1. c) For the manufacturing material:
• Blocks
• Concrete

Simple staircase without handrail

Spiral Staircase

Wooden railing staircase

Before beginning to describe the layout of a staircase, we must know that the comfortable ratio between the footprint and the risers of the rungs is defined by the expression:

2 risers + 1 footprint = 63 cm

63 cm represents the average length of the man’s step on a horizontal piano. For children this value is reduced to approximately 55 cm.

To draw a ladder, the measures given by the plans of the work on floor height, number of steps and slope must be compared. Very precisely, the person responsible for the work or designated operator must set the position of the finished floor level (NPT) of the upper and lower floor to fix the initial and final rungs of the section.

The number of risers is obtained by dividing the slope to be saved by the chosen riser.

The exact measurement of the riser results from dividing the floor height by their number.

The footprint is calculated by replacing the value of two risers of the expression given above.

The length of the flight of stairs, that is, the planar distance between the leading edges is equal to the footprint multiplied by the number of steps minus 1.

Example

An access ladder to a multifamily building must have 18 cm of risers and the height between 280 cm floor. Calculate the number of risers, the exact measure of the riser, the exact measurement of the footprint, and the length of the flight of the stairs.

Solution

1. a) Number of risers = at the height between floor 280 cm: 18 cm which is the height chosen for the risers = 15.55 ~ 16 risers.
2. b) Exact measurement of the riser = at the height between floor 280 cm: 16 which is the number of risers that the ladder carries = 17.5 cm.
3. c) Exact measurement of the footprint: the expression indicated above will be applied, that is, replacing the values ​​already found in said expression:

2 X 17.5 cm + 1 footprint = 63 cm; therefore, 1 footprint = 63 cm – 35 cm = 27 cm.

1. d) The length of the section = to the multiplying of the width of the footprint by the number of steps minus 1 = 27 cm (16 – 1) = 405 cm.

Note: The number of steps on a ladder is equal to the number of risers.