Jump to content
 







Main menu
   


Navigation  



Main page
Contents
Current events
Random article
About Wikipedia
Contact us
Donate
 




Contribute  



Help
Learn to edit
Community portal
Recent changes
Upload file
 








Search  

































Create account

Log in
 









Create account
 Log in
 




Pages for logged out editors learn more  



Contributions
Talk
 



















Contents

   



(Top)
 


1 Etymology  





2 In wood construction  



2.1  Purlin plate  





2.2  Principal purlin  





2.3  Common purlin  







3 In steel construction  





4 Gallery  





5 See also  





6 References  





7 External links  














Purlin






Afrikaans
العربية
Čeština
Deutsch
Eesti
Español
Français
Bahasa Indonesia
Italiano
Nederlands
Norsk bokmål
Oʻzbekcha / ўзбекча
Polski
Русский
Українська

 

Edit links
 









Article
Talk
 

















Read
Edit
View history
 








Tools
   


Actions  



Read
Edit
View history
 




General  



What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Cite this page
Get shortened URL
Download QR code
Wikidata item
 




Print/export  



Download as PDF
Printable version
 




In other projects  



Wikimedia Commons
 
















Appearance
   

 






From Wikipedia, the free encyclopedia
 


A view of a roof using common purlin framing. The purlins are marked in red. This view is from the inside of the building, below the roof. The rafters are the beams of wood angled upward from the ground. They meet at the top of the gable at a ridge beam, which has extra bracing to attach it to the rafters. The purlins are the large beams perpendicular to the rafters; from this shot, it appears that there are three purlins on either side of the roof. The sheathing boards are sometimes called the roof deck and are painted white.

Apurlin (or historically purline, purloyne, purling, perling) is a longitudinal, horizontal, structural member in a roof. In traditional timber framing there are three basic types of purlin: purlin plate, principal purlin, and common purlin.

Purlins also appear in steel frame construction. Steel purlins may be painted or greased for protection from the environment.

Etymology[edit]

Information on the origin of the term "purlin" is scant. The Oxford Dictionary suggests a French origin, with the earliest quote using a variation of purlin in 1447, though the accuracy of this claim has been disputed.

In wood construction[edit]

Purlin plate[edit]

A purlin plate in wood construction is also called an "arcade plate" in European English,[1] "under purlin", and "principal purlin". The term plate means a major, horizontal, supporting timber. Purlin plates are beams which support the mid-span of rafters and are supported by posts. By supporting the rafters they allow longer spans than the rafters alone could span, thus allowing a wider building. Purlin plates are very commonly found in large old barns in North America. A crown plate has similarities to a purlin plate but supports collar beams in the middle of a timber-framed building.

Principal purlin[edit]

Principal purlins in wood construction, also called "major purlins" and "side purlins," are supported by principal rafters and support common rafters in what is known as a "double roof" (a roof framed with a layer of principal rafters and a layer of common rafters). Principal purlins are further classified by how they connect to the principal rafters: "through purlins" pass over the top; "butt purlins" tenon into the sides of the principal rafters; and "clasped purlins," of which only one historic U.S. example is known,[citation needed]) are captured by a collar beam. Through purlins are further categorized as "trenched," "back," or "clasped;" butt purlins are classified as "threaded," "tenoned," and/or[clarification needed] "staggered."[2]

Common purlin[edit]

Common purlins in wood construction, also called a "major-rafter minor-purlin system".[3] Common purlins are typically "trenched through" the top sides (backs) of principal rafters and carry vertical roof sheathing (the key to identifying this type of roof system). Common purlin roofs in North America are found in areas settled by the English and may have been a new invention in the Massachusetts Bay Colony. No examples of framed buildings with common purlin roofs have been reported in England, however some stone barns in England have vertically boarded, common purlin roofs. Historically, these roofs are found in New England, the highest concentration in Maine, and isolated parts of New York and along the St. Lawrence River in Canada. One of the oldest surviving examples is in the Coffin House in Newbury, Massachusetts, from 1678. The purpose of a common purlin roof may be they allow a board roof, that is a roof of nothing but vertically laid boards with seams covered with battens or another layer of boards.[4]

In steel construction[edit]

In steel construction, the term purlin typically refers to roof framing members that span parallel to the building eave,[5] and support the roof decking or sheeting. The purlins are in turn supported by rafters or walls. Purlins are most commonly used in Steel Framed Building Systems, where Z-shapes are utilized in a manner that allows flexural continuity between spans.

Steel industry practice assigns structural shapes representative designations for convenient shorthand description on drawings and documentation: Channel sections, with or without flange stiffeners, are usually referenced as C shapes; Channel sections without flange stiffeners are also referenced as U shapes; Point symmetric sections that are shaped similar to the letter Z are referenced as Z shapes. Section designations can be regional and even specific to a manufacturer. In steel building construction, secondary members such as purlins (roof) and girts (wall) are frequently cold-formed steel C, Z or U sections, (or mill rolled) C sections.

Cold formed members can be efficient on a weight basis relative to mill rolled sections for secondary member applications. Additionally, Z sections can be nested for transportation bundling and, on the building, lapped at the supports to develop a structurally efficient continuous beam across multiple supports.

Gallery[edit]

Note: The sketches in this section reference terminology commonly used in the UK and Australia.[6]

See also[edit]

References[edit]

  1. ^ Harris, Richard. "Bays, frames and boxes." Discovering timber-framed buildings. 3rd revised ed. Aylesbury: Shire Publications, 1979. 10
  • ^ Alcock, N. W. "Purlins." Recording timber-framed buildings: an illustrated glossary. York, England: Council for British Archaeology, 1996. G14, F12.
  • ^ Hubka, Thomas C. "The Buildings". Big house, little house, back house, barn: the connected farm buildings of New England. Hanover [N.H.]: University Press of New England, 1984. p. 41.
  • ^ The origin of the common purlin roof is my studied opinion. These roofs were historically common in northern Europe and may have been brought to the New World by the Pilgrims after their two decades of living in the Netherlands.
  • ^ "What are Purlins - Metsec". voestalpine Metsec. voelstapine Metsec. Retrieved 3 April 2024.
  • ^ Glossary of Australian Building Terms - Third Edition.(NCRB)
  • External links[edit]

     This article incorporates text from a publication now in the public domainChisholm, Hugh, ed. (1911). "Purlin". Encyclopædia Britannica. Vol. 22 (11th ed.). Cambridge University Press. p. 665.


    Retrieved from "https://en.wikipedia.org/w/index.php?title=Purlin&oldid=1218034154"

    Categories: 
    Roofs
    Building engineering
    Structural system
    Timber framing
    Hidden categories: 
    Articles with short description
    Short description matches Wikidata
    All articles with unsourced statements
    Articles with unsourced statements from June 2013
    Wikipedia articles needing clarification from July 2014
    Wikipedia articles incorporating a citation from the 1911 Encyclopaedia Britannica with Wikisource reference
    Wikipedia articles incorporating text from the 1911 Encyclopædia Britannica
    Articles with BNF identifiers
    Articles with BNFdata identifiers
    Articles with J9U identifiers
    Articles with LCCN identifiers
     



    This page was last edited on 9 April 2024, at 09:55 (UTC).

    Text is available under the Creative Commons Attribution-ShareAlike License 4.0; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.



    Privacy policy

    About Wikipedia

    Disclaimers

    Contact Wikipedia

    Code of Conduct

    Developers

    Statistics

    Cookie statement

    Mobile view



    Wikimedia Foundation
    Powered by MediaWiki