STAIRCASE AND ITS FORMS

Stairs can take a large number of forms

The simplest form is the straight flight of stairs, with neither winders nor landings. It is not often used in modern homes because:

the upstairs is directly visible from the bottom of a straight flight of stairs.
it is potentially more dangerous in that a fall is not interrupted until the bottom of the stairs.
a straight flight requires enough space for the entire run of the stairs.

However, a straight flight of stairs is easier to design and construct than one with landings. Additionally, the rhythm of stepping is not interrupted in a straight run, which may offset the increased fall risk by helping to prevent a misstep in the first place.

"L" shaped stairways have one landing and usually change in direction by 90 degrees. "U" shaped stairs may employ a single wider landing for a change in direction of 180 degrees, or 2 landings for two changes in direction of 90 degrees each. Use of landings and a possible change of direction have the following effects:

The upstairs is not directly visible from the bottom of the stairs, which can provide more privacy for the upper floor.
A fall can be arrested at the landing.
Though the landings consume total floor space, there is no requirement for a large single dimension, allowing more flexible floorplan designs.
For larger stairs, particularly in exterior applications, a landing can provide a place to rest the legs.

simple stairs

wooden modular home staircase

glass wing staircase

mediterranean staircase

stainless steel staircase

brick klin touch

wooden simple staircase

Spiral and helical stairs

Spiral stairs in medieval times were generally made of stone and typically wound in a clockwise direction . Extant 14th to 17th century examples of these stairways can be seen atMuchalls Castle, Crathes Castle and Myres Castle in Scotland. Exceptions to the rule exist, however, as may be seen in the accompanying image of the Scala of the Palazzo Contarini del Bovolo, which winds up counter-clockwise.The term "spiral" has a more narrow definition in a mathematical context, as a mathematical spiral lies in a single plane and moves towards or away from a central point. The mathematical term for motion where the locus remains at a fixed distance from a fixed line whilst moving in a circular motion about it is "helical". The presence or otherwise of a central pole does not affect the terminology applied to the design of the structure.

Developments in manufacturing and design have led to the introduction of kit form spiral stairs. Steps and handrails can be bolted together to form a complete unit. These stairs can be made out of steel, timber, concrete or a combination of materials.

Helical or circular stairs do not have a central pole and there is a handrail on both sides. These have the advantage of a more uniform tread width when compared to the spiral staircase. Such stairs may also be built around an elliptical or oval planform. A double helix is 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 (examples:Pozzo di S. Patrizio, Château de Chambord, Château de Blois, Crédit Lyonnais headquarters in Paris). Fire escapes, though built with landings and straight runs of stairs, are often functionally double helices, with two separate stairs intertwined and occupying the same floor space. This is often in support of legal requirements to have two separate fire escapes.

Both spiral and helical stairs can be characterized by the number of turns that are made. A "quarter-turn" stair deposits the person facing 90 degrees from the starting orientation. Likewise there are half-turn, three-quarters-turn and full-turn stairs. A continuous spiral may make many turns depending on the height. Very tall multi-turn spiral staircases are usually found in old stone towers within fortifications, churches and in lighthouses.

Winders may be used in combination with straight stairs to turn the direction of the stairs. This allows for a large number of permutations.