Лестницы: Конструкция и разновидности

Construction designed to bridge a large vertical distance by dividing it into steps

Stairs are a structure designed to bridge a large vertical distance between lower and higher levels by dividing it into smaller vertical distances. This is achieved as a diagonal series of horizontal platforms called steps which enable passage to the other level by stepping from one to another step in turn. Steps are very typically rectangular. Stairs may be straight, round, or may consist of two or more straight pieces connected at angles. Types of stairs include staircases (also called stairways) and escalators. Some alternatives to stairs are elevators (also called lifts), stairlifts, inclined moving walkways, ladders, and ramps. A stairwell is a vertical shaft or opening that contains a staircase. A flight (of stairs) is an inclined part of a staircase consisting of steps (and their lateral supports if supports are separate from steps).

A stair, or a stairstep, is one step in a flight of stairs. In buildings, stairs is a term applied to a complete flight of steps between two floors. A stair flight is a run of stairs or steps between landings. A staircase or stairway is one or more flights of stairs leading from one floor to another, and includes landings, newel posts, handrails, balustrades and additional parts. A stairwell is a compartment extending vertically through a building in which stairs are placed. A stair hall is the stairs, landings, hallways, or other portions of the public hall through which it is necessary to pass when going from the entrance floor to the other floors of a building. Box stairs are stairs built between walls, usually with no support except the wall strings. They provide additional length to the tread without changing the pitch of the stairs. Starting or feature tread: Where stairs are open on one or both sides, the first step above the lower floor or landing may be wider than the other steps and rounded. When the starting step is rounded, the balusters typically are arranged in a true spiral around the circumference of the rounded portion, and the handrail has a flat spiral called a "volute" that connects the tops of the balusters. Besides the cosmetic appeal, starting steps allow the balusters to form a wider, more stable base for the end of the handrail. Handrails that simply end at a post at the foot of the stairs can be less sturdy, even with a thick post. A double ended feature tread can be used when both sides of the stairs are open. There are a number of different styles and uses of feature tread. Stringer board, stringer, or sometimes just string: The structural member that supports the treads and risers in standard staircases. There are typically three stringers, one on either side and one in the center, with more added as necessary for wider spans. Side stringers are sometimes dadoed to receive risers and treads for increased support. Stringers on open sided stairs are called "cut stringers". Tread rise: The distance from the top of one tread to the top of the next tread. Total rise: The distance the flight of stairs raises vertically between two finished floor levels. 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 helical stairway. When three steps are used to turn a 90° corner, the middle step is called a kite winder as a kite shaped quadrilateral. Trim: Various moldings are used to decorate and in some instances support stairway elements. Scotia or quarter round are typically placed beneath the nosing to support its overhang. Curtail step: A decorative step at the bottom of a staircase that usually houses the volute and volute newel turning for a continuous handrail. The curtail tread will follow the flow of the volute.

The balustrade is the system of railings and balusters that prevents people from falling over the edge. Banister, railing, or handrail: The angled member for handholding, as distinguished from the vertical balusters which hold it up for stairs that are open on one side. Railings are often present on both sides of stairs, but can sometimes be only on one side or absent altogether. On wide staircases, there can be one or more railings between the two sides. The term "banister" is sometimes used to mean just the handrail, sometimes the handrail and the balusters, or sometimes just the balusters. Volute: A handrail end element for the bullnose step that curves inward like a spiral. A volute is said to be right or left handed depending on which side of the stairs the handrail is as one faces up the stairs. Turnout: Instead of a complete spiral volute, a turnout deviates from the normal handrail center line away from the flight to give a wider opening as one enters the staircase, The turnout is usually set over a newel post to give added stability to the handrail. Gooseneck: The vertical handrail that joins a sloped handrail to a higher handrail on the balcony or landing is a gooseneck. Rosette: Where the handrail ends in the wall and a half newel is not used, it may be trimmed by a rosette. Easings: Wall handrails are mounted directly onto the wall with wall brackets. At the bottom of the stairs, such railings flare to a horizontal railing and this horizontal portion is called a "starting easing". At the top of the stairs, the horizontal portion of the railing is called an "over easing". Core rail: Wood handrails often have a metal core to provide extra strength and stiffness, especially when the rail has to curve against the grain of the wood. The archaic term for the metal core is "core rail". Baluster: A term for the vertical posts that hold up the handrail. Sometimes simply called guards or spindles. Treads often require two balusters. The second baluster is closer to the riser and is taller than the first. The extra height in the second baluster is typically in the middle between decorative elements on the baluster. That way the bottom decorative elements are aligned with the tread and the top elements are aligned with the railing angle. Newel: A large baluster or post used to anchor the handrail. Since it is a structural element, it extends below the floor and subfloor to the bottom of the floor joists and is bolted right to the floor joist. A half newel may be used where a railing ends in the wall. Visually, it looks like half the newel is embedded in the wall. For open landings, a newel may extend below the landing for a decorative newel drop. Finial: A decorative cap to the top of a newel post, particularly at the end of the balustrade. Baserail, or shoerail: For systems where the baluster does not start at the treads, they go to a baserail. This allows for identical balusters, avoiding the second baluster problem. Fillet: A decorative filler piece on the floor between balusters on a balcony railing. Handrails may be continuous (sometimes called over the post) or post to post (or more accurately newel to newel). For continuous handrails on long balconies, there may be multiple newels and tandem caps to cover the newels. At corners, there are quarter turn caps. For post to post systems, the newels project above the handrails. Another, more classical, form of handrailing that is still in use is the tangent method. A variant of the cylindric method of layout, it allows for continuous climbing and twisting rails and easings. It was defined from principles set down by architect Peter Nicholson in the 18th century.

A fundamental advantage of helical stairs is that they can be very compact, fitting into very narrow spaces and occupying a small footprint. Double helix staircases are possible, with two independent helical stairs in the same vertical space, allowing one person to ascend and another to descend without ever meeting, if they choose different helices. When used in Roman architecture, helical stairs were generally restricted to elite luxury structures. They were then adopted into Christian ecclesiastic architecture. During the Renaissance and Baroque periods, increasingly spectacular helical stairways were devised, first deleting walled enclosures, and then deleting a central post to leave an open well. While clockwise helical staircases are more common in castles than anti clockwise, they were even more common in medieval structures without a military role, such as religious buildings. Studies of helical stairs in castles have concluded that "the role and position of spirals in castles  had a much stronger domestic and status role than a military function"

Alternating tread stairs have been in use since at least 1888. Today, the design is used in some loft apartments to access bedrooms or storage spaces.

Local building codes often dictate the number of emergency exits required for a building of a given size, including specifying a minimum number of stairwells. For any building bigger than a private house, modern codes invariably specify at least two sets of stairs, completely isolated from each other so that if one becomes impassable due to smoke or flames, the other remains usable. The traditional way to satisfy this requirement was to construct two separate stairwell stacks, each occupying its own footprint within each floorplate. Each stairwell is internally configured into an arrangement often called a "U return" or "return" design. The two stairwells may be constructed next to each other, separated by a fireproof partition, or optionally the two stairwells may be located at some distance from each other within the floorplan. These traditional arrangements have the advantage of being easily understood by building occupants and occasional visitors. (1675–1683) was the first known person to establish the ergonomic relationship of tread and riser dimensions. He specified that 2 × riser + tread = step length. It is estimated that a noticeable misstep occurs once in 7,398 uses and a minor accident on a flight of stairs occurs once in 63,000 uses. Stairs can be a hazardous obstacle for some, so some people choose to live in residences without stairs so that they are protected from injury. Stairs are not suitable for wheelchairs and other vehicles. A stairlift is a mechanical device for lifting wheelchairs up and down stairs. For sufficiently wide stairs, a rail is mounted to the treads of the stairs, or attached to the wall. A chair is attached to the rail and the person on the chair is lifted as the chair moves along the rail.

Religious shrines and memorial structures are often approached via stairs, sometimes numbering hundreds or thousands of steps. Many Neoclassical buildings feature prominent wide stairs ascending to an elevated platform or plinth where the main entrance is located. In recent years, increasing concerns about accessibility have encouraged architects to retrofit discreet lower level public entrances or elevators to ease wheelchair access. Large open well helical stairs have been used as a central feature in public buildings from the Renaissance until modern times. Vessel is an artistic structure and visitor attraction which was built as part of the Hudson Yards Redevelopment Project in Manhattan, New York City. Built to plans by the British designer Thomas Heatherwick, the elaborate honeycomb like structure rises 16 stories and consists of 154 flights of stairs, 2,500 steps, and 80 landings for visitors to explore. Stairs may also be a fanciful physical construct such as the "stairs that go nowhere" located at the Winchester Mystery House. The Penrose stairs, devised by Lionel and Roger Penrose, are a famous impossible object. The image distorts perspective in such a manner that the stairs appear to be never ending, a physical impossibility. The image was adopted by M. C. Escher in his iconic lithograph Ascending and Descending.

The longest stairway is listed by Guinness Book of Records as the service stairway for the Niesenbahn funicular railway near Spiez, Switzerland, with 11,674 steps and a height of The stairs are usually employee only, but there is a public run called Niesenlauf once a year. Mount Girnar, one of the holiest of sacred places for Hindu, Jain, and Buddhist followers, and also for some Muslims, is located in Junagadh district in the Indian state of Gujarat in Saurashtrian peninsula. At a height of 1100 metres, with five summits, each adorned with several sacred places, it is accessed on foot by soaring close to 10,000 steps along a rugged terrain and deciduous forest that is also the last home for Asiatic lions. It is the longest completely stone made stairway in the world. Alipiri, India, is one of two ways to reach the Sri Venkateswara Swami Vaari Temple, Tirumala from Tirupati on foot, and it was until recently the only one in modern times. The temple is the richest Hindu temple in the world in terms of donations received and wealth and is visited by about 50,000 to 100,000 pilgrims per day (30 to 40 million people annually on average), while on special occasions and festivals like the annual Brahmotsavam, the number of pilgrims shoots up to 500,000, making it the most visited holy place in the world. Srivari Mettu, about 20 km away, is the original one that was renovated and brought back to use in 2008. Alipiri is the longer route with more than 3550 steps, Srivari Mettu is shorter with 2388 steps. A flight of 7,200 steps (including inner temple Steps), with 6,293 Official Mountain Walkway Steps, leads up the East Peak of Mount Tai in China. The Haiku Stairs, on the island of Oahu, Hawaii, are approximately 4,000 steps which climb nearly Originally used to access long wire radio antennas which were strung high above the Haiku Valley, between Honolulu and Kaneohe, they are closed to hikers. The Flørli stairs, in Lysefjorden, Norway, have 4,444 wooden steps that climb from sea level to It is a maintenance stairway for the water pipeline to the old Flørli hydro plant. The hydro plant is now closed down, and the stairs are open to the public. The stairway is claimed to be the longest wooden stairway in the world. The longest stone stairs in Japan are the 3,333 step stairs of the Shakain temple in Yatsushiro, Kumamoto. The second ones, Mount Haguro stone stairs, have 2,446 steps in Tsuruoka, Yamagata. The CN Tower's staircase reaches the main deck level after 1,776 steps and the Sky Pod above after 2,579 steps; it is the tallest metal staircase on Earth. The Gemonian stairs were infamous as a place of execution during the early Roman Empire, especially during the period postdating Tiberius. The World Trade Center Survivors' Staircase is the last visible structure above ground level at the World Trade Center site. It was originally two outdoor flights of granite clad stairs and an escalator that connected Vesey Street to the World Trade Center's Austin J. Tobin Plaza. During the September 11, 2001, attacks, the stairs served as an escape route for hundreds of evacuees from 5 World Trade Center, a 9 floor building adjacent to the 110 story towers. Stairwell A was the lone stairway left intact after the second plane hit the South Tower of the World Trade Center during the September 11 attacks. It was believed to have remained intact until the South Tower collapsed at 9:59 am. 14 people were able to escape the floors located at the impact zone (including one man who saw the plane coming at him), and 4 people from the floors above the impact zone. Numerous 911 operators who received calls from individuals inside the South Tower were not well informed of the situation as it rapidly unfolded in the South Tower. Many operators told callers not to descend the tower on their own, even though it is now believed that Stairwell A was most likely passable at and above the point of impact. In London, England, a notable staircase is that to the Monument to the Great Fire of London, more commonly known simply as "the Monument". This is a column in the City of London, near the northern end of London Bridge, which commemorates the Great Fire of London. The top of the Monument is reached by a narrow winding staircase of 311 steps. Constructed between 1671 and 1677, it is the tallest isolated stone column in the world. The Spanish Steps in Rome are a monument of late Italian Baroque architecture connecting the Piazza di Spagna with the Trinità dei Monti up the side of the Pincian Hill. Designed by Francesco De Sanctis and constructed 1723–1725, the 135 steps form a wide vista looking down toward the Tiber. The steps are adorned with garden terraces blooming with azaleas and have been widely celebrated in cultural work. The Loretto Chapel in Santa Fe, New Mexico is well known for its helix shaped staircase, which has been nicknamed "Miraculous Stair". It has been the subject of legend and rumor, and the circumstances surrounding its construction and its builder are considered miraculous by the Sisters of Loretto and many visitors. The El Toro 20, a twenty step set of stairs in Lake Forest, California, was well known among skateboarders, BMXers, and inline skaters as a popular and challenging skate spot. The first skateboarder to do an ollie down it was Don Nguyen. The staircase was demolished in 2019. The Grand Staircase of the Titanic was one of the most recognizable features of the British transatlantic ocean liner that sank on her maiden voyage in 1912 after a collision with an iceberg. Decorated stair risers were used extensively in the Greco Buddhist art of Gandhara, to form the pedestal to small devotional stupas. They were usually adorned with friezes, fantastic animals and decorations. A flight of stairs with decorated stair risers from the Chakhil i Ghoundi Stupa has been almost fully restored and can now be seen at the Guimet Museum in Paris. Archaeological research by the Italian IsMEO at the Butkara Stupa suggests that small decorative stairs were adjoined to Buddhist stupas at the time of the Indo Greek Kingdom, and that they were decorated with Buddhist scenes.