Submit Articles | Member Login | Top Authors | Most Popular Articles | Submission Guidelines | Categories | RSS Feeds See As RSS
Forgot Password?    New User?
Welcome to Very Good Articles!

ALL » Other >> View Article

By: Bryson Kaleb
Metal roofing systems are found in many buildings today. They are used extensively in the concrete as well as metal building systems for the many advantages that they provide. A metal roofing system comprises of many different element, one of which is purlins. Here is a look at what these elements are, and their importance in metal roof solutions.

What are purlins?

Purlins are elements or components of roofing structures. They are boards that span rafters or trusses and, provide a way to fasten the roof sheathing and other roofing materials to the building structure. This element was especially found in traditional structures such as barns. However, they are used widely in modern roofing systems, especially metal ones in residential construction, because they lend a unique architectural look. Using purlins creates an illusion that the ceiling floats it’s above the rafters, and this visual element create as distinctive architectural beauty.

How purlins work

Purlins are roof framing members that span parallel to the building eave, and support the sheeting or decking on the roof. These structural elements are in tern supported by the rafters or walls of the building. They are commonly found in metal building systems - typically in the Z shape - which allows for flexural continuity between spans.

Types of purlins

Purlins come in different shapes the most common of which are detailed. below.

• C shape - Those of the square shape or cross section are usually referred as C purlins. In addition to use on rafters and roof comedies, these elements find use in walls as well as floor joists and wall studs.

• Z purlins - These elements, as the name suggests, have a Z shape, and help overlap the joints. They are stronger and sturdier than C purlins. As a result, such purlins used in large scale production specially for roofing.

• RHS purlins - These kinds of purlins are used on roofs where the structural support becomes visible once the construction is complete. They are sturdy and aesthetical, and have hollow caps which can be placed on walls and the ends welded accurately so that no corrosion, seepage or damage take place.

Metal purlins

Purlins made from metal, especially those in steel have a huge fan following in the market. This is because they can be installed easily and also stay put for a longer period of time. Such metal purlins can be assembled using different systems as follows

• Sleeved system - this system ideal for buildings that have two or more bays, and which utilize single span length purlins along with sleeves. They can also be used for those with double spans.

• Butt system - this system is suited, and used primarily in single span applications. They are the simplest purlin systems, and can be used in non-standard configuration whenever required.

• Lap systems - lap systems are further variations of sleeve systems, and are suitable for buildings with five or more bays. Single span purlins are alternatively inverted and overlapped with each other in this system, which has the benefit of achieving a higher degree of continuity. Lap systems allow economic section selection, and also have reduced site erection time.

Buying metal roof purlins

Selection of purlins for metal roofs in building depends on various factors. The first is the material, out of which steel is a popular choice. The next is the section depth, which can range from 121 millimeters to 341 millimeters in standard settings. Many vendors of metal roof purlins also allow for non-standard and customized element sizes depending on the buyer’s need. They can also be availed in different colours or finishes, when needed.

Elite Steel & Supply, one of the leading suppliers of metal building products like metal roofing screws, closures, tape, pipe caps, purlin ( ), rectangular steel tubing to DIY enthusiasts and contractors for projects of all sizes. For more information, visit
See All articles From Author