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A ladder is a
vertical Vertical is a geometric term of location which may refer to: * Vertical direction, the direction aligned with the direction of the force of gravity, up or down * Vertical (angles), a pair of angles opposite each other, formed by two intersecting s ...
or inclined set of rungs or steps used for climbing or descending. There are two types: rigid ladders that are self-supporting or that may be leaned against a vertical surface such as a
wall A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including: * Walls in buildings that form a fundamental part of the supe ...
, and rollable ladders, such as those made of
rope A rope is a group of yarns, plies, fibres, or strands that are twisted or braided together into a larger and stronger form. Ropes have tensile strength and so can be used for dragging and lifting. Rope is thicker and stronger than similarly ...
or
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
, that may be hung from the top. The vertical members of a rigid ladder are called stringers or rails (US) or stiles (UK). Rigid ladders are usually portable, but some types are permanently fixed to a structure, building, or equipment. They are commonly made of metal, wood, or
fiberglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
, but they have been known to be made of tough plastic.


Historical usages

Ladders are ancient tools and technology. A ladder is featured in a
Mesolithic The Mesolithic (Greek: μέσος, ''mesos'' 'middle' + λίθος, ''lithos'' 'stone') or Middle Stone Age is the Old World archaeological period between the Upper Paleolithic and the Neolithic. The term Epipaleolithic is often used synonymous ...
rock painting that is at least 10,000 years old, depicted in the Spider Caves in
Valencia, Spain Valencia ( va, València) is the capital of the autonomous community of Valencia and the third-most populated municipality in Spain, with 791,413 inhabitants. It is also the capital of the province of the same name. The wider urban area also ...
. The painting depicts two humans using a ladder to reach a wild
honeybee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the current cosmo ...
nest to harvest
honey Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...
. The ladder is depicted as long and flexible, possibly made out of some sort of grass.Wilson, Bee (2004). The Hive: The Story Of The Honeybee. London, Great Britain: John Murray (Publishers).


Variations


Rigid ladders

Rigid ladders are available in many forms, such as: *
Accommodation ladder An accommodation ladder is a foldable flight of steps down a ship's side. Accommodation ladders can be mounted parallel or perpendicular to the ship's board. If the ladder is parallel to the ship, it has to have an upper platform. Upper platform ...
, portable steps down the side of a ship for boarding. *
Assault ladder {{Unreferenced, date=May 2007 Escalade is the act of scaling defensive walls or ramparts with the aid of ladders. Escalade was a prominent feature of sieges in ancient and medieval warfare, and though it is no longer common in modern warfare, ...
, used in siege warfare to assist in climbing walls and crossing moats. *
Attic ladder An attic ladder (US) or loft ladder (UK) is a retractable ladder that is installed into an attic door/access panel. They are used as an inexpensive and compact alternative to having a stairway that ascends to the attic of a building. They are usef ...
, pulled down from the ceiling to allow access to an attic or loft. * , a ladder laid horizontally to act as a passage between two points separated by a drop. * Boarding ladder, a ladder used to climb onto a vehicle. May be rigid or flexible, also boarding step(s), and swim ladder. * Cat ladder (US chicken ladder), a lightweight ladder frame used on steep roofs to prevent workers from sliding. * Christmas tree ladder, a type of boarding ladder for
divers Diver or divers may refer to: *Diving (sport), the sport of performing acrobatics while jumping or falling into water *Practitioner of underwater diving, including: **scuba diving, **freediving, **surface-supplied diving, **saturation diving, a ...
which has a single central rail and is open at the sides to allow the diver to climb the ladder while wearing
swimfins Swimfins, swim fins, diving fins, or flippers are finlike accessories worn on the feet, legs or hands and made from rubber, plastic, carbon fiber or combinations of these materials, to aid movement through the water in water sports activities s ...
. * , a fixed ladder with a lower sliding part. A system of counterweights is used to let the lower sliding part descend gently when released. * Extension ladder or "telescopic ladder", a fixed ladder divided into two or more lengths for more convenient storage; the lengths can be slid together for storage or slid apart to expand the length of the ladder; a
pulley A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell that ...
system may be fitted so that the ladder can be easily extended by an operator on the ground then locked in place using the
dogs The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
and
pawl A pawl is a movable lever that engages a fixed component to either prevent movement in one direction or restrain it altogether. As such, it is a type of latch and can also be considered a type of dog. It typically consists of a spring-loaded le ...
s. 65 ft (20 m), 50 ft (15 m) and some 35 ft (10 m) extension ladders for
fire service A fire department (American English) or fire brigade (Commonwealth English), also known as a fire authority, fire district, fire and rescue, or fire service in some areas, is an organization that provides fire prevention and fire suppression se ...
use "bangor poles", "tormentor poles" or "stay poles" to help raise, pivot, steady, extend, place, retract and lower them due to the heavy weight. *
Fixed ladder A fixed ladder is a vertical ladder mounted permanently to a structure. These ladders are primarily used to access roofs or other structures for industrial purposes. In the United States, these ladders are covered by OSHA and ANSI standards. Comp ...
, two side members joined by several rungs; affixed to structure with no moving parts. * , a ladder in the step ladder style with one or more (usually no more than three) one-way hinges. Ideal for use on uneven ground (e.g. stairs), as a trestle or when fully extended a Fixed ladder. Some variations feature a central one-way hinge with extensible locking legs. *
Hook ladder A hook ladder, also known as a pompier ladder (from the French ''pompier'' meaning firefighter) is a type of ladder that can be attached to a window sill or similar ledge by the use of a hooked extending bill with serrations on the underside. The ...
or
pompier ladder A hook ladder, also known as a pompier ladder (from the French ''pompier'' meaning firefighter) is a type of ladder that can be attached to a window sill or similar ledge by the use of a hooked extending bill with serrations on the underside. The ...
, a rigid ladder with a hook at the top to grip a windowsill; used by firefighters. * Mobile Safety Steps are self-supporting structures that have wheels or castors making them easy to move. They sometimes have a small upper platform and a hand rail to assist in moving up and down the steps. * Orchard ladder, a three legged step ladder with the third leg made so that it can be inserted between tree branches for fruit picking. * , a step ladder with a large platform area and a top handrail for the user to hold while working on the platform. * , a ladder that looks like a drainpipe but can be deployed instantly when required. *
Roof A roof ( : roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temper ...
ladder, a rigid ladder with a large hook at the top to grip the ridge of a pitched roof. * , also known as a builder's ladder, has sections that come apart and are interchangeable so that any number of sections can be connected. * Step ladder, a self-supporting portable ladder hinged in the middle to form an inverted V, with stays to keep the two halves at a fixed angle. Step ladders have flat steps and a hinged back. *
Swim ladder Swim or SWIM may refer to: Movement and sport * Swim, a fad dance * Aquatic locomotion, the act of biologically propelled motion through a liquid medium * Human swimming, the useful or recreational activity of movement through water * Swimming ( ...
, a ladder used by swimmers to get out of the water, often on boats. * , commonly used to refer to a hybrid between a step ladder and an extension ladder with 360-degree
hinge A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other ...
s; has three parts and can be taken apart to form two step ladders; e.g.
Little Giant ''Little Giant'' is a 1946 American comedy drama film directed by William A. Seiter and starring the comedy team of Abbott and Costello. The film was released in the UK with the title ''On the Carpet''. Plot A naïve country boy named Benny Mil ...
. * , an "
A-Frame An A-frame is a basic structure designed to bear a load in a lightweight economical manner. The simplest form of an A-frame is two similarly sized beams, arranged in an angle of 45 degrees or less, attached at the top, like an uppercase lett ...
"-style ladder with a telescoping center section. *
Turntable ladder A fire engine (also known in some places as a fire truck or fire lorry) is a road vehicle (usually a truck) that functions as a firefighting apparatus. The primary purposes of a fire engine include transporting firefighters and water to an ...
, an extension ladder fitted to rotating platform on top of a fire truck. * Vertically rising ladder, designed to climb high points and facilitate suspending at said high points. * X-deck ladder, a US patented ladder design that is a combination ladder and scaffold. Rigid ladders were originally made of
wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...
, but in the 20th century
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
became more common because of its lighter weight. Ladders with
fiberglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
stiles are used for working on or near
overhead electrical wire An overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives, trolleybuses or trams. It is known variously as: * Overhead catenary * Overhead contact system (OCS) * Overhead equipmen ...
s, because fiberglass is an electrical insulator.
Henry Quackenbush Henry Marcus Quackenbush (April 27, 1847 – September 8, 1933), commonly called "H.M.", was an American inventor and industrialist who founded the H.M. Quackenbush Company in Herkimer, New York. His company was widely known for its air rifles an ...
patented the extension ladder in 1867.


Flexible ladders

*Rope ladders or Jacob's ladders are used where storage space is extremely limited, weight must be kept to a minimum, or in instances where the object to be climbed is too curved to use a rigid ladder. They may have rigid or flexible rungs. Climbing a rope ladder requires more skill than climbing a rigid ladder, because the ladder tends to swing like a
pendulum A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the ...
. Jacob's ladders used on a ship are used mostly for emergencies or for temporary access to the side of a ship. Steel and aluminum wire ladders are sometimes used in
vertical caving A pit cave, shaft cave or vertical cave—or often simply called a pit (in the US) and pothole or pot (in the UK); jama in South Slavic languages scientific and colloquial vocabulary (borrowed since early research in the Western Balkan Dinaric A ...
, having developed from rope ladders with wooden rungs. Flexible ladders are also sometimes used as swim ladders on boats.


Uses

*Dissipative ladders are portable ladders built to ESD (
Electrostatic Discharge Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two electrically charged objects caused by contact, an short circuit, electrical short or dielectric breakdown. A buildup of static electricity can be caused ...
) standard. Electrostatic Discharge is a natural occurrence in which electricity is passed through the body, or other conductors, and discharges onto some object. For example, the shock sometimes felt when a doorknob is touched is an ESD. This natural occurrence is a very important topic in the field of electronics assembly due to the costly damage ESDs can cause to sensitive electronic equipment. Dissipative ladders are ladders with controlled electrical resistance: the resistance slows the transfer of charge from one point to another, offering increased protection during ESD events: ≥105 and < 1012 Ω / square. *Boarding and pool ladders, also swim ladders and dive ladders. A ladder may be used on the side or stern of a boat, to climb into it from the water, and in a swimming pool, to climb out and sometimes in. Swimming pool ladders are usually made from plastic, wood or metal steps with a textured upper surface for grip and metal rails at the sides to support the steps and as handrails for the user, and are usually fixed in place. Boarding ladders for boats may be fixed, but are usually portable, and often fold away when not in use to avoid drag when under way. Boarding ladders may also be used for other types of vehicle, or boarding steps which are supported directly by the vehicle structure. *Assault ladders


Safety

The most common injury made by ladder climbers is
bruising A bruise, also known as a contusion, is a type of hematoma of tissue, the most common cause being capillaries damaged by trauma, causing localized bleeding that extravasates into the surrounding interstitial tissues. Most bruises occur close e ...
from falling off a ladder, but
bone fracture A bone fracture (abbreviated FRX or Fx, Fx, or #) is a medical condition in which there is a partial or complete break in the continuity of any bone in the body. In more severe cases, the bone may be broken into several fragments, known as a '' ...
s are common and
head injuries A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...
are also likely, depending on the nature of the accident. Ladders can cause injury if they slip on the ground and fall. To avoid this, they tend to have plastic feet or base pads which increase friction with the ground. However, if the plastic is badly worn, the aluminium may contact the ground increasing the chance of an accident. Ladder stabilizers are also available to increase the ladder's grip on the ground. One of the first ladder stabilizers or ladder feet was offered in 1936 and today they are standard equipment on most large ladders. A ladder standoff, or stay, is a device fitted to the top of a ladder to hold it away from the wall. This enables the ladder to clear overhanging obstacles, such as the eaves of a
roof A roof ( : roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temper ...
, and increases the safe working height for a given length of ladder because of the increased separation distance of the two contact points at the top of the ladder. It has become increasingly common to provide anchor points on buildings to which the top rung of an extension ladder can be attached, especially for activities like window cleaning, especially if a fellow worker is not available for "footing" the ladder. Footing occurs when another worker stands on the lowest rung and so provides much greater stability to the ladder when being used. However footing a ladder should be seen as a last resort for a safe placement. The anchor point is usually a ring cemented into a slot in the brick wall to which the rungs of a ladder can be attached using rope for example, or a
carabiner A carabiner or karabiner () is a specialized type of shackle, a metal loop with a spring-loaded gate used to quickly and reversibly connect components, most notably in safety-critical systems. The word is a shortened form of ''Karabinerhaken' ...
. If a leaning ladder is placed at the wrong angle, the risk of a fall is greatly increased. The safest angle for a ladder is 75.5°; if it is too shallow, the bottom of the ladder is at risk of sliding, and if it is too steep, the ladder may fall backwards. This angle is achieved by following the 4 to 1 rule for a ladder placed on a vertical wall: for every four feet of vertical height, the ladder foot should move one foot from the wall. Both scenarios can cause significant injury, and are especially important in industries like construction, which require heavy use of ladders.


Ladder classes

The European Union and the United Kingdom established a ladder certification system – ladder classes – for any ladders manufactured or sold in Europe. The certification classes apply solely to ladders that are portable such as stepladders and extension ladders and are broken down into three types of certification. Each ladder certification is colour-coded to indicate the amount of weight the ladder is designed to hold, the certification class and its use. The color of the safety label specifies the class and use. * Class 1 ladder – for heavy-duty industrial uses, maximum load of 175 kg. Colour-coded blue to identify. * Class EN131 ladders – for commercial uses, maximum load of 150 kg. No specific colour code.. * Class III ladders – for light, domestic uses, maximum load of 125 kg. Colour-coded red to identify.


Society and culture

A common
superstition A superstition is any belief or practice considered by non-practitioners to be irrational or supernatural, attributed to fate or magic, perceived supernatural influence, or fear of that which is unknown. It is commonly applied to beliefs and ...
in English-speaking countries is that walking under a ladder is seen as bad luck. Some sources claim that this stems from the image of a ladder being propped up against a wall looking similar to a
gallows A gallows (or scaffold) is a frame or elevated beam, typically wooden, from which objects can be suspended (i.e., hung) or "weighed". Gallows were thus widely used to suspend public weighing scales for large and heavy objects such as sacks ...
, while others attribute it to ancient Egyptian traditions involving
pyramid A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilat ...
s and
triangle A triangle is a polygon with three Edge (geometry), edges and three Vertex (geometry), vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC. In Euclidean geometry, an ...
s representing the trinity of the gods, and passing through the triangular shape made by a ladder against a wall was seen as desecration. Ladders have also been linked to the
crucifixion of Christ The crucifixion and death of Jesus occurred in 1st-century Judea, most likely in AD 30 or AD 33. It is described in the four canonical gospels, referred to in the New Testament epistles, attested to by other ancient sources, and considere ...
, with author and scientist
Charles Panati Charles Panati (born March 13, 1943) is a former college professor, industrial physicist, author and science editor of ''Newsweek''. Biography Panati was born in Baltimore, Maryland, and raised in Atlantic City, New Jersey. After graduating fr ...
noting that many believe a ladder rested against the crucifix that Christ hung from, making it a symbol of wickedness, betrayal and death. In comedic children's media, the image of a character walking under a ladder being the cause or result of bad luck has become a common trope.


Image gallery

File:Rough ladder instead of stairs. Nako, HP, India. 2010.jpg, Rough ladder instead of stairs, Nako, HP, India, 2010 File:Hausbuch Wolfegg 53v 53v1 Drehbank Waage Steiggeräte.jpg, On the right hand page are types of ladders from the end of the 15th century in Germany File:COLLECTIE TROPENMUSEUM De tau-tau van een vorst wordt uit het graf gehaald om opnieuw te worden aangekleed op de begraafplaats der vorsten van Sangalla' TMnr 20000480.jpg, A ladder used for ceremonial purposes in
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
File:Échelle Dogon.jpg,
Dogon Dogon may refer to: *Dogon people, an ethnic group living in the central plateau region of Mali, in West Africa *Dogon languages, a small, close-knit language family spoken by the Dogon people of Mali *'' Dogon A.D.'', an album by saxophonist Juliu ...
ladder in Africa File:Dog and pawl.jpg, Photo of a dog and pawl on an extension ladder File:La-cat.gif, Sketch of Cat Ladder (UK terminology), which aids work on steep roofs File:La-main.gif, Sketch of double extension ladder File:Bamboo ladder in Hainan - 02.JPG, Detail of a bamboo ladder, common in China File:Maison Doucet.jpg, A roof ladder, held in place by hooks extending over the ridge File:LADDER CROSSING.jpg, Lightweight aluminum ladder used in the
Khumbu Icefall The Khumbu Icefall is located at the head of the Khumbu Glacier and the foot of the Western Cwm, which lies at an elevation of on the Nepali slopes of Mount Everest, not far above Base Camp and southwest of the summit. The icefall is considered ...


See also

* * * * *Scala naturae *


References


External links


OSHA Ladder guidelines
including
OSHA OSHA or Osha may refer to: Work * Occupational Safety and Health Administration, a federal agency of the United States that regulates workplace safety and health * Occupational Safety and Health Act (United States) of 1970, a federal law in the Un ...
approved rung spacing requirements, etc.
CDC – NIOSH Update – New NIOSH Smart Phone App Addresses Ladder Safety

Ladders 101 - American Ladder Institute. Includes use & care of different types of ladders, ladder terms & links to safety standards.
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