Purlin is a horizontal beam or bar used for structural support in structures, most often below the roof. Purlins are supported either by the building’s rafters or its walls. These are most commonly used in metal buildings, but in wood-frame structures, these also replace closely packed rafters. A roof’s purlins support the roof Deck’s weight. The roof deck is the wooden panel, ply board, or sheet metal which creates the roof surface. This is usually filled with some kind of weather proofing and constructed from concrete and often an insulation material.

There are many types of Purlins and are divided into groups depending on the material they are made of and the form of their shape. Different purlins are used for multiple uses including a structural wall or floor support. Purlin is necessary as there is no frame for the sheeting on the roof to rest on without it, thereby making purlins important to the roof structure.

What is Purlins?

In comparison to closely spaced rafters, the use of purlins is common in pre-engineered metal construction systems and both the ancient post-and-beam and newer pole construction methodologies for frame construction.

Purlins pass roof loads to the major structural elements supporting the roof; the form and arrangement of purlins is a design factor that depends on the instance of roof loads as well as the limiting sheeting lengths to use. In the final analysis, local building codes should always be understood and implemented in the design of a concrete roof structure.

Steel purlins are a substitute for conventional wood purlins. They are lightweight, stable in dimension, accurate and simple. In extreme temperature changes, they expand and contract moderately. Steel purlin is typically made of cold-formed material, which is thin enough to get through the screws. Cold-formed steel is rendered in the desired shape by rolling or pressing thin sheets of steel in. To the producer, it is less costly than hot-rolled steel and is, therefore, simpler to deal with. Though cold-formed steel is stronger than hot-formed steel when under strain, it is more likely to crack rather than bend.

Purlins are made of different metals. Some are simple Mild steel having normal strength and some are with zinc coating of different GSM. In harsh weather special coating can be applied over and above zinc coating.

Types of Cold Formed Purlins:

C purlins, as the name implies, are formed as in the C alphabet, which is primarily used to support walls and floors. C section purlins or cee section purlins are built to shape a building shell structure’s walls and floor joists, making them also suitable for supporting the beams required for flooring. These may also use our C segment purlins with door mounting, roof clipping, window trimming, parapet rails, and side rails.

Both of our purlins in section C have similar extensions on their ends, which means they can be used in single spans. These are freestanding and secure, allowing them to be easily managed while being mounted while also offering stable support in the system.

Sizes Available for C Purlins:

C section purlins are available in a wide range of thicknesses and are manufactured to the exact specifications of the customer up to any length, enabling them to be easily modified for use in buildings of various sizes. Bansal also manufactures them un-drilled or with different diameter pre-drilled holes (Oval shape and round shape holes of any dimensions can be provided on request). Web height up to 300 mm is available and thickness up to 3.2 mm is available.

C purlins, also known as Cee purlins, are in the shape of the letter C and provide structural support for beams required for walls and flooring. In addition to roofing, C purlins are often used for structural support in walls and as floor joists.

C Purlins
C Purlins are horizontal structures that are used to support the load from the roof deck or the sheathing. The plane surface of this purling on one side has made it a preferred material for cladding due to its easy installation on concrete structures or steel. Our range purlins are light in weight and perfect for simple span construction.
Features :
• Optimum quality
• Easy installation
• High tensile strength
• Abrasion & corrosion resistance
Advantages of C Purlins :
•Ability to span length
•Purlin erection is easier than others
•Fast to erect and easy handling
•No side drilling/cutting required
•Assured dimensions and straightness
•High durability, versatility and uniform quality
•Low transportation cost due to decreased weight

Z Shaped Purlin:

Another form of Z purlin is stronger than C purlin and is mostly used together at joints and overlaps. Z purlins or zed purlins are horizontal beams that are built to shape a building shell structure’s roof and wall joists. They sit between the roofing sheets and the building, acting as sheet support to ensure that it is firmly attached and secure in place. Due to its relatively high flexibility and lightweight properties Z purlins are most commonly used in agricultural and industrial buildings which make them easily adapted for use in a variety of different sizes.

Sizes Available for Z Purlins:

we manufacture Z purlins in a broad range of thicknesses that can be produced up to any length to suit your exact requirements. We can also manufacture them un-drilled or with any diameter pre-drilled holes according to your requirements. (Oval shape and round shape holes of any dimensions can be provided on request). Web height up to 300 mm is available and thickness up to 3.2 mm is available.

C Shaped SIGMA Purlins:

C shaped with having special ribs (Bends in web) are known as “SIGMA” purlins.

These types of purlins are having good structural properties and supersedes above two varieties of purlins. Sigma section purlins are built to shape a building shell structure’s walls and floor joists, making them also suitable for supporting the beams required for flooring. These may also use our C segment purlins with door mounting, roof clipping, window trimming, parapet rails, and side rails.

What Purpose Do Purlins Serve in a Steel Building?

To understand this we really need to get down to the basics of roof purlins in metal construction. Purlins are an integral part of a pre-engineered structural steel package. Such structural supports extend through the rafter beams perpendicularly. Often known as “sheeting sheets,” purlins provide the roofing portion of a steel building’s secondary framing. Three structural functions are provided by metal roofing purlins.

Firstly, the roof is protected by the purlins. Second, purlins tie the rafters together, stabilizing and reinforcing the rigid framing of the frame. And the third, between the spans of the individual framing bays, purlins provide additional support. As an added benefit, purlins increase the resistance of the system to excessive rainfall.