A Photograph of the Norman Roof Truss in the Attic of the Bolduc House in Ste Genevieve MO

A king post (or king-post or kingpost) is a central vertical post used in architectural or bridge designs, working in tension to support a beam below from a truss

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex, ...

above (whereas a

crown post A crown post is a term in traditional timber framing for a post in roof framing which stands on a '' tie beam'' or ''collar beam'' and supports a ''collar plate''.Alcock, N. W.. Recording timber-framed buildings: an illustrated glossary. London ...

, though visually similar, supports items above from the beam below). In aircraft design a strut called a king post acts in compression, similarly to an architectural crown post. Usage in mechanical plant and marine engineering differs again, as noted below.

Architecture

A king

post Post or POST commonly refers to: *Mail, the postal system, especially in Commonwealth of Nations countries **An Post, the Irish national postal service **Canada Post, Canadian postal service **Deutsche Post, German postal service **Iraqi Post, Ira ...

extends vertically from a

crossbeam A beam is a structural element that primarily resists loads applied laterally to the beam's axis (an element designed to carry primarily axial load would be a strut or column). Its mode of deflection is primarily by bending. The loads applied to ...

(the

tie beam A tie, strap, tie rod, eyebar, guy-wire, suspension cables, or wire ropes, are examples of linear structural components designed to resist tension. It is the opposite of a strut or column, which is designed to resist compression. Ties may be ...

) to the

of a triangular

truss A truss is an assembly of ''members'' such as beams, connected by ''nodes'', that creates a rigid structure. In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assembl ...

. The king post, itself in

tension Tension may refer to: Science * Psychological stress * Tension (physics), a force related to the stretching of an object (the opposite of compression) * Tension (geology), a stress which stretches rocks in two opposite directions * Voltage or el ...

, connects the apex of the truss with its base, holding up the tie beam (also in tension) at the base of the truss. The post can be replaced with an iron rod called a king rod (or king bolt) and thus a king rod truss. The king post truss is also called a "Latin truss". In traditional timber framing, a

looks similar to a king post, but it is very different structurally: whereas the king post is in tension, usually supporting the tie beam as a truss, the crown post is supported by the tie beam and is in

compression Compression may refer to: Physical science *Compression (physics), size reduction due to forces *Compression member, a structural element such as a column *Compressibility, susceptibility to compression * Gas compression *Compression ratio, of a ...

. The crown post rises to a crown plate immediately below and supporting collar beams, it does not rise to the apex like a king post. Historically a crown post was called a king post in England but this usage is obsolete. An alternative truss construction uses two

queen post A queen post is a tension member in a truss that can span longer openings than a king post truss. A king post uses one central supporting post, whereas the queen post truss uses two. Even though it is a tension member, rather than a compression me ...

s (or queen-posts). These vertical posts, positioned along the base of the truss, are supported by the sloping sides of the truss, rather than reaching its apex. A development adds a collar beam above the queen posts, which are then termed queen struts. A section of the tie beam between the queen posts may be removed to create a

hammerbeam roof A hammerbeam roof is a decorative, open timber roof truss typical of English Gothic architecture and has been called "...the most spectacular endeavour of the English Medieval carpenter". They are traditionally timber framed, using short beams pr ...

King post truss

The king post truss is used for simple roof trusses and short-span bridges. It is the simplest form of truss in that it is constructed of the fewest truss members (individual lengths of wood or metal). The truss consists of two diagonal members that meet at the apex of the truss, one horizontal beam that serves to tie the bottom end of the diagonals together, and the king post which connects the apex to the horizontal beam below. For a roof truss, the diagonal members are called

rafter A rafter is one of a series of sloped structural members such as wooden beams that extend from the ridge or hip to the wall plate, downslope perimeter or eave, and that are designed to support the roof shingles, roof deck and its associated ...

s, and the horizontal member may serve as a ceiling

joist A joist is a horizontal structural member used in framing to span an open space, often between beams that subsequently transfer loads to vertical members. When incorporated into a floor framing system, joists serve to provide stiffness to the s ...

. A bridge would require two king post trusses with the driving surface between them. A roof usually uses many side-by-side trusses depending on the size of the structure.

Pont-y-Cafnau The Pont-y-Cafnau (Welsh, meaning ''bridge of troughs''), sometimes written ''Pont y Cafnau'' or ''Pontycafnau'', is a long iron truss bridge over the River Taff in Merthyr Tydfil, Wales. The bridge was designed by Watkin George and built i ...

, the world's first iron railway bridge, is of the king post type.

History

King posts were used in

timber-framed Timber framing (german: Holzfachwerk) and "post-and-beam" construction are traditional methods of building with heavy timbers, creating structures using squared-off and carefully fitted and joined timbers with joints secured by large wooden ...

roof construction in Roman buildings, and in

medieval architecture Medieval architecture is architecture common in the Middle Ages, and includes religious, civil, and military buildings. Styles include pre-Romanesque, Romanesque, and Gothic. While most of the surviving medieval architecture is to be seen in c ...

in buildings such as

parish church A parish church (or parochial church) in Christianity is the church which acts as the religious centre of a parish. In many parts of the world, especially in rural areas, the parish church may play a significant role in community activities, ...

es and

tithe barn A tithe barn was a type of barn used in much of northern Europe in the Middle Ages for storing rents and tithe A tithe (; from Old English: ''teogoþa'' "tenth") is a one-tenth part of something, paid as a contribution to a religious orga ...

s. The oldest surviving roof truss in the world is a king post truss in

Saint Catherine's Monastery Saint Catherine's Monastery ( ar, دير القدّيسة كاترين; grc-gre, Μονὴ τῆς Ἁγίας Αἰκατερίνης), officially the Sacred Autonomous Royal Monastery of Saint Katherine of the Holy and God-Trodden Mount Sinai, ...

, Egypt, built between 548 and 565. King posts also appear in

Gothic Revival architecture Gothic Revival (also referred to as Victorian Gothic, neo-Gothic, or Gothick) is an architectural movement that began in the late 1740s in England. The movement gained momentum and expanded in the first half of the 19th century, as increasingly ...

Queen Anne style architecture The Queen Anne style of British architecture refers to either the English Baroque architecture of the time of Queen Anne (who reigned from 1702 to 1714) or the British Queen Anne Revival form that became popular during the last quarter of the ...

and occasionally in modern construction. King post trusses are also used as a structural element in wood and metal bridges. A painting by Karl Blechen circa 1833 illustrating construction of the second Devil's Bridge (''Teufelsbrücke'') in the

Schöllenen Gorge Schöllenen Gorge (german: Schöllenenschlucht; Schöllenen) is a gorge formed by the upper Reuss in the Swiss canton of Uri between the towns of Göschenen to the north and Andermatt to the south. It provides access to the St Gotthard Pass. ...

shows multiple king posts suspended from the apex of the

falsework Falsework consists of temporary structures used in construction to support a permanent structure until its construction is sufficiently advanced to support itself. For arches, this is specifically called centering. Falsework includes temporary s ...

upon which the masonry arch has been laid. In this example, beams in compression are supported by each king post several feet below the apex, and the bottom of the king posts can clearly be seen to be unsupported.

Norman truss

Architectural historians in the French colonial cities

St Louis St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, which e ...

Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...

and

New Orleans New Orleans ( , ,New Orleans
Merriam-Webster. ; french: La Nouvelle-Orléans , es, Nuev ...

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

use the term "Norman roof" to refer to a steeply pitched roof; it is supported by what they call a "Norman truss" which is similar to a king post truss. This is a through-purlin truss consisting of a tie beam and paired truss blades, with a central king post to support the roof ridge. The name derives from a belief that this system of construction was introduced to North America by settlers from

Normandy Normandy (; french: link=no, Normandie ; nrf, Normaundie, Nouormandie ; from Old French , plural of ''Normant'', originally from the word for "northman" in several Scandinavian languages) is a geographical and cultural region in Northwestern ...

in northern France, but it is really a misnomer as the system was more widely used than that. The difference between a Norman truss and a king post truss is the tie beam in a Norman truss is technically a collar beam (a beam between the rafters above the rafter feet) where the king post truss the rafters land on top of a tie beam. DFEAscenderIIIC01

Aviation

King posts are also used in the construction of some wire-braced aircraft, where a king post supports the top cables or "ground wires" supporting the wing. Only on the ground are these wires from the kingpost in tension, while in the air under positive g flight they are unloaded.

Mechanical plant

The very robust hinge connecting the boom to the chassis in a backhoe, similar in function and appearance to a large automotive kingpin, is called a king post.

Marine engineering

On a

cargo ship A cargo ship or freighter is a merchant ship that carries cargo, goods, and materials from one port to another. Thousands of cargo carriers ply the world's seas and oceans each year, handling the bulk of international trade. Cargo ships are usu ...

or oiler a king post is an upright with cargo-handling or fueling rig devices attached to it. On a cargo vessel king posts are designed for handling cargo, and so are located at the forward or after end of a hatch. For an oiler they are located over the fuel transfer lines.

References

Notes Bibliography * *{{cite book , last=Wood , first=De Volson , title=Treatise on the Theory of the Construction of Bridges and Roofs , url=https://archive.org/details/treatiseontheor03woodgoog , year=1883 , publisher=J. Wiley & Sons

External links

Bridge BasicsTimber roofsCrown post roofsKing and Queen post roofs on the former mansion at Parlington, near Aberford in Yorkshire, England
(archived) Architectural elements Structural engineering Trusses Timber framing Truss bridges by type