Humans have always been constricted to the ground by our relatively-unchanged biological limitations. The tallest man who ever lived in recorded history, Robert Pershing Wadlow, stood at 8’11”. Today, the average female height is 5’4” and the average male height is 5’9”, which is a significant increase from historical times, but is still minuscule compared to the heights of trees and geological features that have always towered above us. However, humans have never really needed an increased body height, since our minds have been innovating our way of life even before civilization. Archaeologists have confirmed that ladders date back to at least 10,000 years ago. They are an ancient, but still-relevant technology that has allowed us to access places that we would naturally be constrained from.
The most common material used in the construction of ladders is aluminum (or aluminium), due to its cheap cost and light weight. ANSI ASC A14.2-2007: American National Standards for Ladders - Portable Metal - Safety Requirements sets guidelines for the safe construction, design, testing, and care for portable metal ladders of different types. This includes ladders that are considered to be Special Duty, Extra Heavy-Duty, Heavy-Duty, Medium Duty, and Light Duty. The working load that these different ladder types can carry ranges from 200-375 pounds.
Since we were never meant to leave the ground, very strict precautions should be taken for the structure of ladders. ANSI ASC A14.2-2007 provides recommendations for the spacing between rungs, angle of inclination, and the correct workmanship for the bolts, rivets, and welds that are holding the pieces of the ladder together. The standard also identifies tests that should be used to determine if the ladder meets the guidelines for the five types of portable metal ladders. This involves using test loads on the rungs and side rails to determine how much weight they can support. This will ensure safety and efficiency for any individual operating the ladder.
Despite its popularity among ladder users, metal cannot be used for all processes that need to reach reasonable heights. The American Ladder Institute (ALI), a nonprofit association dedicated to ladder safety, also has standards dedicated to the proper construction and management of wood ladders (ANSI ASC A14.1-2007: American National Standards for Ladders - Wood Safety Requirements) and plastic ladders (ANSI ASC A14.5-2007: American National Standards for Ladders - Portable Reinforced Plastic - Safety Requirements). Ladders constructed of these materials are well-suited for environments where metal ladders are not safe to use, specifically in the presence of electrical equipment.
Other standards by the ALI include:
ANSI ASC A14.3-2008: American National Standards for Ladders - Fixed - Safety Requirements
ANSI ASC A14.4-2009: American National Standard Safety Requirements for Job Made Wooden Ladders
ANSI ASC A14.7-2006: American National Standard for Mobile Ladder Stands and Mobile Ladder Stand Platforms
ANSI ASC A14.7-2011: Safety Requirements for Mobile Ladder Stands and Mobile Ladder Stand Platforms
ANSI ASC A14.8-2013: Safety Requirements for Ladder Accessories
ANSI-ASC A14.9-2010: Safety Requirements for Disappearing Attic Stairways
All ladders must always be used for the purpose for which they were designed and be given the care that allows for continued use.