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Everything You Need to Know About Steel Purlins

Structure of steel roof frame for home construction. Concept of

What should you know about steel purlins?

  1. Basics of steel purlins
  2. Types of steel purlins
  3. Reasons to choose steel purlins


When you’re considering the toughness and sturdiness of your roof, you’ll need to have an understanding of the most effective building materials to use. As one of the most fundamental building parts, the roof provides all-around support. It not only protects inhabitants from outdoor elements but also stabilizes the framework of the entire building. Therefore, in choosing any kind of roofing, you’ll do well with understanding everything to know about steel purlins. The structural strength of these materials allows them to be suitable in various types of roof installations — from sheet roofing to deck roofing, no matter the kind of material.

Many homeowners and building owners have since turned to steel purlins for their roofing requirements, especially where long-lastingness and durability are concerned. But if it’s your first time encountering purlins, then it’s best to know its basics to see if these are the right choices for you. In this guide, you’ll learn more about the definition of steel purlins, their different types, and the like. Read on to learn more.


Basics of Steel Purlins

Steel frame under the roof

In general, purlins make up the secondary roof framing parts that are found in the building. Almost always, these materials run parallel to the eaves of a building — or the structure that is horizontally projected beyond the side of the building. There are some cases where the term “purlins” may also refer to basically anything that comprises the roofing network, be it a longitudinal, horizontal, or structural member.

The manufacturing process for steel purlins is similar to what you’ll find in most structural steel materials to date, that is, through cold-forming. This method starts off with a steel coil or unwound steel sheets/strips that pass through metal fabrication equipment. The finished product is a fully-formed C or Z-cross sectional steel purlin that can come in a variety of heights — 100, 150, 200, etc. — and thicknesses that range from 1.0 to 3.00 mm BMT (base metal thickness).


Types of Steel Purlins

Several unique features that you’ll find across different types of purlins are the flat surface and the flanges or the opposing legs that provide support to the flat section. In C-section purlins, the bottom and top flanges are equally sized and can support a range of non-continuous or continuous spans. C-section purlins, however, cannot be lapped together due to their shape and form.

On the other hand, Z-section purlins have been produced with a diagonally-positioned broad flange and narrow flanges. This allows for lapping and can be used to increase the thickness of the purlins wherever possible — i.e. if the roofing sheet is made out of thicker material, or if a single purlin cannot bear the load of a heavy ceiling/roofing deck.

Steel purlins are considered to be low-profile and lightweight, which makes them highly ductile and machinable. As they are mainly used in roof applications, the purlins need to be cut or punched in order to accommodate different connectors to complete the roof structure. For bolt-based connectors, different bridging, cleats, nuts, or washers can be used. However, boltless connectors are also possible, with added support for compression, tension, bending or any other impact force that may be applied on the purlins.


Reasons to Choose Steel Purlins

Structure of steel roof frame for home construction. Concept of

Some popular uses of steel purlins include agricultural warehouses, logistics warehouses, commercial buildings, barebones spaces, parking lots, or even pre-engineered metal buildings.

Because of the simple manufacturing process, availability, and cost-effectiveness of steel purlins, there’s no wonder why different industries capitalize on their advantages. Other reasons why they’re the preferred construction materials can be traced back to the production technique as well as the grade of steel.

High-grade steel purlins are usually produced from galvanized steel with high tensile strength and ductility — G450, G500, or G550. Galvanized steel has a competitive advantage over other types of non-galvanized steel because it does not rust or oxidize. This can greatly reduce any expenses related to roofing maintenance and repair.

More than that, the purlins can even last for as long as 10 decades, provided that they have been installed properly. This is especially true for enclosed buildings where various operations can lead to the production of runoffs that may affect the quality of the purlins — moisture, chemical compounds, other metals, etc. For any type of building, steel purlins — especially galvanized ones — have proven to be a suitable choice, even under environmentally aggressive conditions.


Key Takeaway

Everything to know about steel purlins has been elaborated in this guide — from its basic definition, types, and reasons to choose this popular building material. Made out of cold-formed steel, steel purlins are highly ductile and have an excellent tensile strength rating. No matter which design is chosen — C-shaped or Z-shaped — this construction material can offer optimal load-bearing support to all kinds of roofing, protect the building’s interiors, and prevent any structural deformities.

In need of high-grade steel purlins for your roof or everyday construction needs? Rely on Regan Industrial’s expertise in steel manufacturing to get the job done for you. Click here for more information! You may also reach us here to learn more about our steel purlin selections.

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