Comment, Like, & Favorite
Spiral stairs wind around a newel (also the central pole). They typically have a handrail on the outer side only, and on the inner side just the central pole. A squared spiral stair assumes a square stairwell and expands the steps and railing to a square, resulting in unequal steps (larger where they extend into a corner of the square). A pure spiral assumes a circular stairwell and the steps and handrail are equal and positioned screw-symmetrically. A tight spiral stair with a central pole is very space efficient in the use of floor area. Spiral stairs have the disadvantage of being very steep. Unless the central column is very large, the circumference of the circle at the walk line will be small enough that it will be impossible to maintain a normal tread depth and a normal rise height without compromising headroom before reaching the upper floor. To maintain headroom most spiral stairs have very high rises and a very short going. Most building codes limit the use of spiral stairs to small areas or secondary usage.
The term "spiral" is used incorrectly for a staircase from a mathematical viewpoint, as a mathematical spiral lies in a single plane and moves towards or away from a central point. A spiral staircase by the mathematical definition therefore would be of little use as it would afford no change in elevation. The correct 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 "helix". The presence or otherwise of a central pole does not affect the terminology applied to the design of the structure.
Spiral stairs in medieval times were generally made of stone and typically wound in a clockwise direction (from the ascendor's point of view), to place attacking swordsmen (who were most often right-handed) at a disadvantage . This asymmetry forces the right-handed swordsman to engage the central pike and degrade his mobility compared with the defender who is facing down the stairs. Extant 14th to 17th century examples of these stairways can be seen at Muchalls 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 anti-clockwise.
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: 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..The first terraced houses in the United States were Carstairs Row in Philadelphia, designed by builder and architect Thomas Carstairs circa 1799 through 1820, for developer William Sansom, as part of the first speculative housing developments in the United States. Carstairs Row was built on the southern part of the site occupied by "Morris' Folly" – Robert Morris’ unfinished mansion designed by L'Enfant. Prior to this time houses had been built not in rows, but individually. It can be contrasted with Elfreth's Alley, the oldest continuously occupied road in the U.S., where all the houses are of varying heights and widths, with different street lines, doorways and brickwork.
Terrace housing in American usage generally continued to be called townhouses in the United States. In Baltimore, Philadelphia, San Francisco, and Washington DC, they are simply called row houses or row homes, and are very common. Despite the narrow lots, many row houses are relatively large, some being over 2,000 square feet. A townhouse in the northeast refers to newer constructions of Terraced houses, of suburban nature, especially.
In much of the Southern United States, they are referred to as row homes. In the United States the term commonly describes a two story, owner-occupied housing unit that shares a wall with one or more neighboring units. If you share a ceiling or floor, it is simply referred to as a multi level apartment.
In the Midwest and Great Plains (and often in Georgia), they are referred to as "townhomes." The term is not terribly specific, a townhome sometimes implies one side of a duplex that is owned.
Row houses in Baltimore's Charles Village neighborhood
Most of Baltimore's housing consists of row houses. Many of Baltimore's row houses date back to colonial times. The style and materials used in their constructions vary throughout the city. A sizable quantity of Baltimore's row houses are clad with formstone, a distinct feature of Baltimore's row houses, typically found in working class areas of the city. Marble Steps also set Baltimore's row houses distinct from other cities' row houses. Much like Philadelphia, some areas of the city that contain row houses are neglected.
In Chicago, row houses can be found in the downtown & surrounding areas developed in the late 1800s through 1930s. Many are 3-flat buildings (consisting of 1 or sometimes 2 apartments on a 3 floored building). A "greystone" is similar to the "brownstone" found in NY, except the facade is clad in Indiana Limestone. Most row houses are separated by a gangway that leads under the common wall between the houses leading to the rear of the property (where sometimes a rear house or coach house exists) & alleyway.
 New Orleans
Creole Townhouses, New Orleans French Quarter
New Orleans has a distinctive style of terrace house in the French Quarter known as the Creole Townhouse and are part of what makes the city famous. The facade of the building sits on the property line, with an asymmetrical arrangement of arched openings. Creole Townhouses have a steeply pitched roof, side-gabled, with several roof dormers. The exterior is made of brick or stucco.
 New York City
A distinctive type found in New York City, among other cities, is called a brownstone. Some newer row houses, which are especially prominent in neighborhoods like Middle Village, Woodhaven and Jackson Heights in Queens and Bensonhurst, Bay Ridge, Park Slope, Canarsie and Marine Park in Brooklyn and Williamsbridge, Wakefield, and Soundview in The Bronx are commonly referred to in Queens and the Bronx as "attached houses".
Historic homes on Elfreth's Alley, Philadelphia
In historic Philadelphia, almost the entire city is populated with various types of row houses. Many of Philadelphia's row houses date back to colonial times. The style and type of material used in constructing Philadelphia's row houses vary throughout the city. Most homes are primarily red brick in construction, with stone and marble accent. There are some communities in the city where the homes are built of solid granite, such as Mayfair in Northeast Philadelphia and Mt. Airy in Northwest Philadelphia. West Philadelphia has many colorful row houses in the Queen Anne architectural style.
 San Francisco
Haight Ashbury, San Francisco
San Francisco is also famous for its houses. The "Painted Ladies" on Steiner Street, Alamo Square, although not strictly "terraced" are a symbol of the city. Other homes labelled as painted ladies around the city are terraced and many others are semi-detached. It should be noted that the painted ladies of San Francisco do not fit the definition of rowhouses, though due to their close proximity to one another, they are mistaken for rowhouses.
January 1st, 2012
Viewed 190 Times - Last Visitor from Full, 01 - Switzerland on 09/08/2014 at 3:36 PM
copy and paste to your website / blog - preview