{"id":12389,"date":"2023-09-01T04:42:36","date_gmt":"2023-09-01T04:42:36","guid":{"rendered":"https:\/\/norsteelbuildings.com\/stage\/pannes-en-acier-ce-que-vous-devez-savoir\/"},"modified":"2026-01-05T19:39:19","modified_gmt":"2026-01-05T19:39:19","slug":"pannes-en-acier-ce-que-vous-devez-savoir","status":"publish","type":"post","link":"https:\/\/norsteelbuildings.com\/fr\/systemes-de-batiments-en-acier\/pannes-en-acier-ce-que-vous-devez-savoir\/","title":{"rendered":"Pannes en acier : ce que vous devez savoir"},"content":{"rendered":"\t\t
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Have you ever looked up at the interior of a steel structure and wondered: \u201cwhat are those bars supporting the roof called?\u201d Well, if you have, then you\u2019ve come to the right article to find your answer.

The answer to this question, of course, is the title of this blog: purlins<\/strong>. A crucial component of most building structures, purlins are what \u2013 literally \u2013 keep the roof over your head. They are an important part of most building structures and are a mark of quality when it comes to steel building structures.

This article will help you understand the role purlins play in the integrity of your steel building structure, so you can make a more informed purchasing decision for your next building. Proper structural integrity and load support is key to the longevity of a building, and to the safety of a building\u2019s occupants. Understanding whether your building requires purlins, what material they should be made of, and what shape they should take, are all questions you should have the answer to before building a new structure \u2013 so let\u2019s dive in!<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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What are Purlins?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Found in most large structures, purlins are the horizontal beams that provide structural support to a building by helping to pass roof loads to other major structural elements<\/strong>. They carry the weight of the roof sheeting, panels, and any additional loads \u2014 such as snow, rainwater, or roof accessories \u2014 and transfer that weight to the major structural elements of the building. In other words, they\u2019re what keep your roof safely in place.<\/p>


By diffusing the load across rafters, walls, or metal support beams, purlins ensure that no single part of the structure bears the entire weight of the roof. How many purlins a roof requires, as well as their size and thickness, will always depend on the specific design loads of the building.<\/p>


Purlins can be classified by their shape, material, and intended use. Among all options, steel purlins<\/strong> are the industry standard. Unlike wood, steel will not rot, warp, or weaken under moisture, and its expansion and contraction in varying climates is minimal. That\u2019s why steel purlins are the reliable choice for long-term structural performance.<\/p>


Most metal purlins are made from cold-formed steel<\/strong> \u2014 thin steel sheets rolled and pressed into shape. This process produces components that are strong, lightweight, and easy to work with. To further protect against corrosion, the finished purlins are galvanized, coating the steel in zinc for lasting durability. Galvanized steel purlins can often be recognized by their distinctive crystal-like \u201cspangle\u201d pattern.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Purlins, Girts, and the Secondary Framing System: A Necessary Partnership<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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When talking about purlins in construction<\/strong>, it is important to remember that they are not working alone. Purlins are part of what is called the secondary framing system \u2014 and their horizontal counterparts, girts, play an equally important role.<\/p>

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Together, steel purlins and girts<\/strong> form the grid of support that ties the entire building envelope back to the primary framing. Purlins carry the roof loads and transfer them to the rafters, while girts support the wall panels and connect them to the columns. Both components also provide convenient attachment points<\/strong> for cladding, insulation, and accessories, making them critical to the overall building envelope.<\/p>

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This partnership is what gives metal building purlins their importance beyond the roof itself. By working together, purlins and girts ensure the structure can handle snow accumulation, wind loads, and other forces while maintaining rigidity and safety<\/strong>. Without a properly engineered secondary framing system, a steel building would lack the load paths it needs to perform as designed.<\/p>


If you would like to explore the history and other key components of a pre-engineered steel building, take a look at our blog Everything You Should Know About Pre-Engineered Metal Buildings<\/a>.<\/p>


That is why quality purlins and girts are always engineered with the primary frame in mind, creating a complete system where every element contributes to the building\u2019s long-term strength and reliability.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Why Purlins Are Used in Metal Buildings<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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While we now understand what purlins are, we want to reinforce the reasons why they are used. Purlins add to the structural integrity of a building\u2019s roof by running perpendicular to the rafter beams (see adjacent image).<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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So why are purlins used in metal buildings? There are 3 structural functions provided by purlins for metal roofing.<\/p>

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