Purlins and Girts for Roofing and Secondary Framing

Purlins and girts are essential components of a building's secondary framing system. They provide additional support to the roof and walls, helping to distribute loads more evenly.

Purlins are horizontal beams placed between rafters to support the roof's decking. They typically span between 20 and 40 feet, depending on the design.

Girts, on the other hand, are horizontal beams attached to the exterior of the wall to provide additional support and help secure the exterior sheathing. They can be installed at various intervals, but typically not more than 8 feet apart.

The spacing and size of purlins and girts can vary depending on the building's design and load requirements.

A purlin is a longitudinal beam that's used to brace trusses or rafters together, transferring external loads on the roof to the top chord of the truss.

Purlins are designed to withstand gravity and wind loads that cause them to sag, so sag rods are added to provide lateral support at discrete points.

Purlins can also be used as girts for wall cladding, providing a structural support system for the exterior of a building.

The design of purlins involves applying loads on the normal and tangential axes of the section's centroid, with biaxial bending being the primary concern.

Torsional effects on the member are typically neglected due to the partial lateral and torsional restraints provided by the roof sheathing.

The maximum distance between steel purlins should be about 1200 mm in residential buildings, with a typical distance of 600 to 800 mm.

To estimate the depth of the purlins, you can use the rule of thumb: depth = span/32. This can be rounded up to the nearest whole number.

C-section purlins are used in simple, non-continuous spans, while Z-section purlins are used in continuous lines of purlins for lapping at internal supports.

The manufacturer's products should specify material properties like material density and other information essential for design checks.

To calculate purlin capacity, you can use the SkyCiv Purlin Capacity Calculator, which presents a simplified approach to checking the section's capacity considering its geometric and material properties, roof configuration, and loads.

The calculator requires input for the bay length, purlin spacing, roof angle, and the location of the sag rod, as well as load cases adapting the ASD design approach.

Here's a rough guide to the maximum distance between purlins based on roof sheathing thickness:

Keep in mind that the spacing of the purlins will typically be smaller than the span of the purlins to create a smaller uniformly distributed load along the length of the purlins.

Purlins and girts are manufactured in C and Z profiles, which cater to a wide range of roof and wall construction needs.

These profiles are made from high-tensile galvanised steel, which adheres to rigorous AS1397 Australian standards to ensure durability and performance.

Ausdeck offers a wide range of sizes, from 100mm to 350mm, to suit specific project requirements.

You can choose between punched and unpunched options, and even specify the web, flange and lip size, thickness, and material strength for custom sections.

Purlins and girts are available in various sizes, including 100mm, 150mm, 200mm, 250mm, 300mm, and 350mm, to suit different construction applications.

Ausdeck keeps a limited inventory of stocked lengths in different sizes for immediate needs, making it convenient to get what you need quickly.

Purlins and girts come in various depths and thicknesses to suit different applications. The LYSAGHT CEE plus™ is available in depths of 102, 152, 200, 240, 250, and 300.

The material specifications for the LYSAGHT CEE plus™ include galvanised steel complying with AS1397-2001, available in G550, G450, and G350 grade steel with Z275, Z275, and Z120 coating.

Some common thickness ranges for the LYSAGHT CEE plus™ include 1, 1.2, 1.5, 1.9, and 2.4. The ZED-Plus ™ (90 deg) is available in depths of 152, 200, 250, and 300, with thickness ranges of 1, 1.2, 1.5, 1.9, and 2.4.

Here is a summary of the available depths and thickness ranges for some of the purlin and girt options:

We manufacture and deliver purlins and girts within your specified timeframe, minimising downtime for our clients. This ensures that our clients can get back to work quickly and efficiently.

Our lead times are responsive because we understand the importance of meeting deadlines. We work closely with our clients to ensure that their needs are met.

We can manufacture and deliver purlins and girts within a timeframe that suits your business. This flexibility allows you to plan your projects with confidence.

Specifications are a crucial part of any product or tool, and understanding them can make all the difference in getting the job done right.

The depth of various sections can range from 102 to 300, depending on the specific product.

LYSAGHT CEE plus, for instance, is available in depths of 102, 152, 200, 240, 250, and 300.

The thickness of these sections can vary, but common options include 1, 1.2, 1.5, 1.9, and 2.4.

For example, the 152 depth of LYSAGHT CEE plus is available in thicknesses of 1, 1.2, 1.5, 1.9, and 2.4.

The material specifications for these sections are also important to consider.

Galvanised steel complying with AS1397-2001 is a common material used in these products, available in G550, G450, and G350 grade steel with Z275, Z275, and Z120 coating.

Here's a summary of the available depths and thicknesses for some of the products mentioned:

Purlins and girts are versatile structural elements used in various applications.

They're often used in agricultural buildings to provide support for roofing and walls.

Purlins can also be found in industrial settings, such as warehouses and factories, where they help distribute loads and maintain structural integrity.

Girts are commonly used in residential construction, particularly in frame construction, to provide additional support to walls.

In some cases, purlins and girts are used in conjunction with each other to create a more robust structure.

For instance, in a metal building, purlins can be used to support the roof, while girts are used to frame the walls.