Stairs
Some alternatives to stairs are elevators (also called lifts), stairlifts, inclined moving walkways, ladders, and ramps.
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.
Stairs may also return onto themselves with 180° angle landings at each end of straight flights forming a vertical stairway commonly used in multistory and highrise buildings.
These types of stairs were commonly used in traditional homes, as they are relatively easy to build and only need to be connected at the top and bottom.
The rhythm of stepping is not interrupted in a straight run, which may offset an increased fall risk by helping to prevent a misstep in the first place.
However, many long straight runs of stairs will require landings or winders to comply with safety standards in building regulations.
Helical is possibly the least poetic but also the most accurate generic title.The term "spiral" has a more narrow definition in a mathematical context, as a curve which lies in a single plane and moves towards or away from a central point, with a continuously changing radius.
Helical stairs, sometimes referred to in architectural descriptions as vice, wind around a newel (also called the "central pole").
A "pure helix" fills a circular stairwell, and has multiple steps and handrail elements which are identical and positioned screw-symmetrically.
A fundamental advantage of helical stairs is that they can be very compact, fitting into very narrow spaces and occupying a small footprint.
[16]: 54 For this reason, they can often be found in ships and submarines, industrial installations, small loft apartments, and other locations where floorspace is scarce.
[16]: 81 However, this compactness can come at the expense of requiring great craftsmanship and care to produce a safe and effective structure.
[16]: 54 By contrast, grand helical stairs occupying wide sweeps of space can also be built, to showcase luxurious funding and elegant taste.
The cylindrical spaces they occupy can have a narrow or wide diameter: "Open well" helical or circular stairs designed by architects often do not have a central pole, but there usually is a handrail at both sides of the treads.
Lacking a central pole, an open well staircase is supported at its outer periphery, or in some cases may be a completely self-supporting and free-standing structure.
In self-supporting stairs, the helix needs to be steep to allow the weight to distribute safely down the structure in the most vertical manner possible.
Building codes may limit the use of helical stairs to small areas or secondary usage, if their treads are not sufficiently wide or have risers taller than 9.5 inches (240 mm).
[16]: 74 For examples, the Pozzo di San Patrizio allows one-way traffic so that laden and unladen mules can ascend and descend without obstruction, while Château de Chambord, Château de Blois, and the Crédit Lyonnais headquarters ensure separation for social purposes.
[16]: 67 There is a common misconception that helical staircases in castles rose in a clockwise direction, to hinder right-handed attackers.
[24] 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"[24] and that "there are sufficient examples of anticlockwise stairs in Britain and France in [the 11th and 12th centuries] to indicate that the choice must have depended both on physical convenience and architectural practicalities and there was no military ideology that demanded clockwise staircases in the cause of fighting efficiency or advantage".
[25] Such a fanciful origin of the term has since been disproved, with experts finding no mention in any historical literature of stairs that were believed to prevent access by witches.
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.
[28] Some architects save floor footprint space while still meeting the exit requirement, by housing two stairwells in a "double helix" or "scissors stairs" configuration whereby two stairwells occupy the same floor footprint, but are intertwined while being separated by fireproof partitions along their entire run.
[28] Some building codes recommend using a color-coded stripe and signage to distinguish otherwise identical-looking stairwells from each other, and to make following a quick exit path easier.
Nicolas-François Blondel in the last volume of his Cours d'architecture[29] (1675–1683) was the first known person to establish the ergonomic relationship of tread and riser dimensions.
Length of flights The approved document refers to 16 risers (steps) for utility stairs and 12 for general access.
Many Neoclassical buildings feature prominent wide stairs ascending to an elevated platform or plinth where the main entrance is located.
Large open-well helical stairs have been used as a central feature in public buildings from the Renaissance until modern times.
[42][43] 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.
