Stairway

Stairway, staircase, stairwell, flight of stairs, or simply stairs are names for a construction designed to bridge a large vertical distance by dividing it into smaller vertical distances, called steps. Stairways may be straight, round, or may consist of two or more straight pieces connected at angles.

Special stairways include escalators and ladders. Some alternatives to stairways are elevators, stairlifts and inclined moving sidewalks as well as stationary inclined sidewalks.

Contents

Components and terminology

Step

The step is composed of the tread and riser.

Tread 
The part of the stairway that is stepped on. It is constructed to the same specifications (thickness) as any other flooring. The tread "depth" is measured from the outer edge of the step to the vertical "riser" between steps. The "width" is measured from one side to the other.
Riser 
The vertical portion between each tread on the stair. This may be missing for an "open" stair effect.
Nosing 
An edge part of the tread that protrudes over the riser beneath. If it is present, this means that, measured horizontally, the total "run" length of the stairs is not simply the sum of the tread lengths, as the treads actually overlap each other slightly.
Starting step or Bullnose 
Where stairs are open on one or both sides, the first step above the lower floor may be wider than the other steps and rounded. The balusters typically form a semicircle around the circumference of the rounded portion and the handrail has a horizontal spiral called a "volute" that supports the top 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 bullnose can be used when both sides of the stairs are open.
Stringer, Stringer board or sometimes just String 
The structural member that supports the treads and risers. There are typically two stringers, one on either side of the stairs; though the treads may be supported many other ways. The stringers are sometimes notched so that the risers and treads fit into them. Stringers on open-sided stairs are often open themselves so that the treads are visible from the side. Such stringers are called "cut" stringers. Stringers on a closed side of the stairs are closed, with the support for the treads routed into the stringer.
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 spiral 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 
Trim (e.g. quarter-round or baseboard trim) is normally applied where walls meet floors and often underneath treads to hide the reveal where the tread and riser meet. Shoe moulding may be used between where the lower floor and the first riser meet. Trimming a starting step is a special challenge as the last riser above the lower floor is rounded. Flexible, plastic trim is available for this purpose, however wooden mouldings are still used and are either cut from a single piece of rounded wood, or bent with laminations Scotia is concave moulding that is underneath the nosing between the riser and the tread above it.

The railing system

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; there is often a railing on both sides, sometimes only on one side or not at all, on wide staircases there is sometimes also one in the middle, or even more. The term "banister" is sometimes used to mean just the handrail, or sometimes the handrail and the balusters or sometimes just the balusters.[1]
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 is a quarter-turn rounded end 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 a "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 which 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.

Other terminology

Balcony 
For stairs with an open concept upper floor or landing, the upper floor is functionally a balcony. For a straight flight of stairs, the balcony may be long enough to require multiple newels to support the length of railing. In modern homes, it is common to have hardwood floors on the first floor and carpet on the second. The homeowner should consider using hardwood nosing in place of carpet. Should the carpet be subsequently replaced with hardwood, the balcony balustrade may have to be removed to add the nosing.
Flight 
A flight is an uninterrupted series of steps.
Floating stairs 
A flight of stairs is said to be "floating" if there is nothing underneath. The risers are typically missing as well to emphasize the open effect. There may be only one stringer or the stringers otherwise minimized. Where building codes allow, there may not even be handrails.
Landing or Platform 
A landing is the area of a floor near the top or bottom step of a stair. An intermediate landing is a small platform that is built as part of the stair between main floor levels and is typically used to allow stairs to change directions, or to allow the user a rest. A half landing is where a 180° change in direction is made, and a quarter landing is where a 90° change in direction is made (on an intermediate landing).[2] As intermediate landings consume floor space they can be expensive to build. However, changing the direction of the stairs allows stairs to fit where they would not otherwise, or provides privacy to the upper level as visitors downstairs cannot simply look up the stairs to the upper level due to the change in direction.
Runner 
Carpeting that runs down the middle of the stairs. Runners may be directly stapled or nailed to the stairs, or may be secured by a specialized bar that holds the carpet in place where the tread meets the riser, known as a stair rod.
Spandrel 
If there is not another flight of stairs immediately underneath, the triangular space underneath the stairs is called a "spandrel". It is frequently used as a closet.
Staircase 
This term is often reserved for the stairs themselves: the steps, railings and landings; though often it is used interchangeably with "stairs" and "stairway". In the UK, however, the term "staircase" denotes what in the U.S. is called "stairway", but usually includes the casing – the walls, bannisters and underside of the stairs or roof above.
Stairway 
This term is often reserved for the entire stairwell and staircase in combination; though often it is used interchangeably with "stairs" and "staircase".
Stairwell 
The spatial opening, usually a vertical shaft, containing an indoor stairway; by extension it is often used as including the stairs it contains.

Measurements

The measurements of a stair, in particular the rise height and going of the steps, should remain the same along the stairs.[3]

The following stair measurements are important:

The easiest way to calculate the rise and run is to use a stair stringer calculator.

Ergonomics and building code requirements

Ergonomically and for safety reasons, stairs must have certain measurements so that people can comfortably use them. Building codes typically specify certain measurements so that the stairs are not too steep or narrow. Building codes specify the following parameters:[4]

Jacques-François Blondel in his 1771 Cours d'architecture[8] was the first known person to establish the ergonomic relationship of tread and riser dimensions.[9] He specified that 2 x riser + tread = step length.[10]

It is estimated that a noticeable mis-step occurs once in 7,398 uses and a minor accident on a flight of stairs occurs once in 63,000 uses.[11] 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. A chair is attached to the rail and the person on the chair is lifted as the chair moves along the rail.

USA building regulations

See http://www.amezz.com/ibc-stairs-code.htm

See http://stairways.org - Stairway Manufacturers' Association

UK building regulations

(overview of Approved document K - Stairs Ramps and Guards)[12]

Approved document K categorises stairs as ‘Private’, ‘Institutional or assembly’ and ‘other’

When considering stairs for private dwellings

Building regulations are required for stairs used where the difference of level is greater than 600mm

Steepness of stairs – Rise and Going - Any rise between 155mm and 220mm used with any going between 245mm and 260mm or any rise between 165mm and 200mm used with any going between 223mm and 300mm

Maximum Rise 220mm and Minimum Going 220mm remembering that the maximum pitch of private stairs is 42⁰. The normal relationship between dimensions of the rise and going is that twice the rise plus the going (2R + G) should be between 550mm and 700mm

Construction of steps - Steps should have level treads, they may have open risers but if so treads should overlap at least 16mm. Domestic private stairs are likely to be used by children under 5 years old so they should be constructed so that a 100mm diameter sphere cannot pass though the opening in the risers.

Headroom - A headroom of 2m is adequate. Special considerations can be made for loft conversions see paragraph 1.10 of the approved document for clarification on the 1.9 tapering to 1.8m

Width of flights - No recommendations are given for stair widths in the Approved document K for stairs but designer’s attention is drawn to approved document B: fire safety.

Length of flights - The approved document refers to 16 risers (steps) for stairs in shops or assembly building. There is no requirement for private stairs. In practice there will be less than 16 steps as 16 x 220mm gives over 3.5m total rise which is way above that in a domestic situation.

Landings - Level, unobstructed landings should be provided at the top and bottom of every flight. The width and length being at least that of the width of the stairs and can include part of the floor. A door may swing across the landing at the bottom of the flight but must leave a clear space of at least 400mm across the whole landing

Tapered steps - There are special rules for stairs with tapered steps as shown in the image Example of Winder Stairs above

Alternate tread stairs can be provide in space saving situations

Guarding - Flights and landings must be guarded at the sides where the drop is more than 600mm. As domestic private stairs are likely to be used by children under 5 the guarding must be constructed so that a 100mm diameter sphere cannot pass through any opening or constructed so that children will not be able to climb the guarding. The height for internal private stairs should be at least 900mm and be able to withstand a horizontal force of 0.36 kN/m

Forms

Stairs can take a large number of forms, combining winders and landings.

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

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.

Most modern stairs incorporate at least one landing. "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:

Spiral and helical stairs

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),[13] 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.

History

See also: List of ancient spiral stairs

The earliest spiral staircases appear in Temple A in the Greek colony Selinunte, Sicily, to both sides of the cella. The temple was constructed around 480–470 BC.[14]

Alternating tread stairs

Where there is insufficient space for the full run length of normal stairs, alternating tread stairs may be used. Alternating tread stairs allow for safe forward-facing descent of very steep stairs. The treads are designed such that they alternate between treads for each foot: one step is wide on the left side; the next step is wide on the right side. There is insufficient space on the narrow portion of the step for the other foot to stand, hence the person must always use the correct foot on the correct step. The slope of alternating tread stairs can be as high as 65 degrees as opposed to standard stairs which are almost always less than 45 degrees. The advantage of alternating tread stairs is that people can descend face forward. The only other alternative in such short spaces would be a ladder which requires backward-facing descent. Alternating tread stairs may not be safe for small children, the elderly or the physically challenged. Building codes typically classify them as ladders and will only allow them where ladders are allowed, usually basement or attic utility or storage areas not frequently accessed.

The image on the right illustrates the space efficiency gained by an alternating tread stair. The alternating tread stair appears in the image's center, with green-colored treads. The alternating stair requires one unit of space per step: the same as the half-width step on its left, and half as much as the full-width stair on its right. Thus, the horizontal distance between steps is in this case reduced by a factor of two, reducing the size of each step.

The horizontal distance between steps is reduced by a factor less than two if for construction reasons there are narrow "unused" steps.

There is often (here also) glide plane symmetry: the mirror image with respect to the vertical center plane corresponds to a shift by one step.

Alternating tread stairs have been in use since at least 1888.[15]

Notable stairways

Image in art

Stairway is a metaphor of achievement or loss of a position in the society, a metaphor of hierarchy (e.g. Jacob's Ladder, The Battleship Potemkin).

Staircase art

Staircase art is an esoteric art form practiced in small pockets, information about staircase artists can be found here.

Gallery

Spiral (double helix) stairs of the Vatican Museums 
Ise Jingū in Japan. 
Angkor Wat in Cambodia. 
Modified stairway for the elderly in Thailand. 
The Potemkin Stairs (1834–41) in Odessa, Ukraine. 
Spiral stairs with ornamental balusters. 
Rudkhan Castle, Fouman, Iran. 
Stairs of rock placed in a natural passage. 
Outdoor stairway on the Alameda Ridge in Portland, Oregon, United States. 
Pioneer spiral staircase, Deaf Smith County Historical Museum, Hereford, Texas. 
Emperor's Stairs in the Residenz of Munich, Bavaria, Germany. 
The 19th century theatre of Weißenhorn, Germany. 
Endless stairway at KPMG, Munich, Germany. 
Wooden spiral stairs in the tower of Salisbury Cathedral. 
A stair and a sculpture in the Fontevraud Abbey 
Nabataean stairway in Beida ("Little Petra"), Jordan 
Foot-worn staircase of the Plovdiv Roman amphitheatre showing multiple repairs. 

See also

References

  1. ^ "Banister". Merriam Webster dictionary. http://m-w.com/cgi-bin/dictionary?book=Dictionary&va=banister. Retrieved 2 November 2010. 
  2. ^ Stairplace Ltd
  3. ^ a b c d Neufert, Ernst; Neufert, Peter (2000). Architects' Data (3rd ed.). Blackwell Science. p. 191. ISBN 0-632-05771-8. 
  4. ^ "A-Mezz Engineered IBC Stairs". http://www.amezz.com/ibc-stairs-code.htm. Retrieved 2 November 2010. 
  5. ^ State of California
  6. ^ "Popular Mechanics homepage". http://www.popularmechanics.com/how_to_central/home_clinic/1275341.html. Retrieved 2 November 2010. 
  7. ^ NFPA 101 Life Safety Code Handbook Tenth Edition 2006, Coté and Harrington, ISBN 0-87765-697-5, pg.167
  8. ^ "Bartleby online". http://www.bartleby.com/65/bl/BlondelF.html. Retrieved 2 November 2010. 
  9. ^ "?". http://97.1911encyclopedia.org/S/ST/STAIRCASE.htm. 
  10. ^ "?". http://www.generativeart.com/2000/KOUTAMANIS_GA_2000.HTM. 
  11. ^ "Stair Safety: A Review of the Literature and Data Concerning Stair Geometry and Other Characteristics". http://www.toolbase.org/Best-Practices/Codes-Regulations-Standards/stair-safety. Retrieved 2 November 2010. 
  12. ^ http://www.inbalance-energy.co.uk/building_regulations/Approved%20Document%20K%20Protection%20from%20Falling%20(1998).pdf
  13. ^ "Stairs". BBC.co.uk. 23 January 2001. http://www.bbc.co.uk/dna/h2g2/A506611. Retrieved 2 November 2010. 
  14. ^ Ruggeri, Stefania: „Selinunt“, Edizioni Affinità Elettive, Messina 2006, ISBN 88-8405-079-0, p. 77
  15. ^ James H. Monckton (1891). Moncktons One Plane Method Of Hand Railing and Stair Building, Copyright 1888. John Wiley & Sons. p. Plate 2, Figure 4. 
  16. ^ "?". http://www.guinnessworldrecords.com/gwr5/content_pages/record.asp?recordid=49700. 
  17. ^ "Welcome to Lysefjord". http://www.lysefjordeninfo.no/en/. Retrieved 2 November 2010. 
  18. ^ National Commission on Terrorist Attacks (July 22, 2004 (first edition)). The 9/11 Commission Report. W. W. Norton & Company. pp. 294. ISBN 0393326713. http://govinfo.library.unt.edu/911/report/911Report_Ch9.pdf. 
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