Metal Roof Purlins – Types, Sizes, Gauge & Finishes

What Is a Metal Purlin?

When constructing any building with metal panels, or metal roofing, your project will likely require the use of metal purlins. A metal purlin is a horizontal beam used in building construction to support and stabilize a metal roofing or wall structure. Purlins are typically made of metal, such as steel, aluminum, or hot-dipped galvanized steel, and come in various shapes, including C purlins and Z purlins. They are placed perpendicular to the roof framing members (such as rafters or trusses) and serve as supporting structures, distributing the load of the roof or wall to the main structural elements.

At ETAS, our metal purlins are commonly used in commercial and industrial buildings and in some residential metal roofs. Our metal purlins offer several advantages, including their lightweight yet sturdy nature, which makes them cost-effective and easy to handle during installation. Additionally, our metal purlins are durable and provide excellent structural support, allowing for greater design flexibility and the ability to span long distances without the need for supporting columns or beams.

Types of Metal Purlins

C Section Steel Purlins

C Purlins, also referred to as Cee purlins due to their distinctive letter C shape, play a crucial role in providing essential structural support for beams and metal panels used in walls and flooring. Typically made from galvanized steel, they are widely utilized for reinforcing walls and serving as floor joists. One of their notable advantages lies in their remarkable ability to span considerable lengths, making them ideal for various construction builds.

Additionally, C purlins eliminate the need for side drilling or cutting, ensuring a streamlined installation process and assuring straightness throughout. This style of galvanized steel purlin offers exceptional durability, contributing to the overall stability and longevity of the structures they support.

Z Section Steel Purlins

Z Purlins, also known as Zee Purlins, play a vital role in constructing shell structures, or pre-engineered metal buildings, serving as horizontal beams for roof and wall joists. Appropriately named for their resemblance to the letter Z, these purlins offer overlapping joints, making them exceptionally strong and sturdy compared to C purlins. Their ability to provide superior strength and durability makes them a popular choice for large-scale structures. 

One significant advantage of a Z Purlin over a C Purlin is its unique shape, allowing for convenient overlapping during installation. This overlapping feature enhances their load-bearing capacity and contributes to more efficient use of materials, as it reduces the required purlin height. These galvanized Z Purlins offer lasting performance and structural integrity, making them an excellent choice for various building projects.

Metal Purlin Finishes

Red Oxide Purlin

Red oxide metal purlins, also known as painted purlins, feature a thin, red oxide coating applied to the surface. This coating serves as a protective measure to prevent rust formation during transportation and storage. However, it is essential to note that the red oxide coating is not a final coat of paint, and when exposed to the elements, the purlins will eventually develop rust.

Despite its rust-preventive function, the red oxide coating is not intended for prolonged outdoor exposure, and additional protective measures or a final coat of paint may be required to maintain the purlins’ appearance and durability over time. Red oxide purlins are ideal if you are looking for a less expensive option, and the purlins are not exposed to weather elements.

Galvanized Metal Purlins

Galvanized metal purlins are an excellent choice for construction projects requiring maximum durability and corrosion resistance. The galvanization process involves applying zinc-alloy plating to the metal, creating a protective barrier against corrosion. This makes galvanized purlins ideal for harsh environments, such as chemical plants or coastal areas, where exposure to saltwater would otherwise lead to rusting in unfinished steel.

While galvanized steel is not entirely immune to oxidation and may develop white rust when exposed to moisture, it still outperforms non-galvanized alternatives in longevity and resilience. For projects requiring long-lasting support near the ocean or in other corrosive environments, galvanized metal purlins prove to be the optimal and reliable choice.

Purlin Sizes

Metal purlin sizes are diverse and versatile, catering to a range of construction needs. These essential building components are offered in various dimensions, including 12g (up to 21 inches), 14g (up to 24 inches), and 16g (up to 16 inches). The selection of sizes allows for flexibility in accommodating different structural requirements. Additionally, they are available in multiple finishes, including red oxide, gray, and galvanized, allowing you to choose the most suitable purlins for your projects. 

Metal Purlin Spacing

Metal purlin spacing plays a crucial role in ensuring the structural integrity and stability of a construction project. The appropriate spacing between purlins is determined based on the anticipated weight the structure will carry and the load capacity of the metal panels. For heavier loads, shorter distances between purlins are required to provide sufficient support. This crucial decision is guided by metal panel and purlin load charts, which aid in determining the optimal spacing for each job.

At ETAS, we collaborate with our clients to assess their project requirements and calculate the correct purlin spacing, ensuring a safe and reliable construction. Finding the right balance in purlin spacing is essential, as it directly impacts the number of purlins needed for the job, which can influence the overall material cost. By finding the optimal purlin spacing, we can help clients achieve cost-efficiency without compromising the structural integrity of their project.

Metal Purlin Gauges

Metal purlins come in a range of gauges, including 12 gauge, 14 gauge, and 16 gauge. The choice of the appropriate gauge depends on the specific requirements and demands of the construction project. Each gauge has its unique strength and load-bearing capabilities, making it essential to select the most suitable gauge for optimal structural support. At ETAS, our team of experts collaborates closely with our clients to assess the project’s needs and recommend the best purlin gauge accordingly. With our expertise and knowledge, we ensure that the selected gauge aligns perfectly with the project’s specifications, providing the necessary strength and reliability to create a robust and long-lasting structure.

Start Your Next Project With ETAS Today

Whether you have questions about metal purlins or are ready to start your next construction project, ETAS is here to help! With nearly 20 years of industry experience and a qualified team dedicated to personalized customer service, you can trust ETAS to help you find the right materials for your project. Simply get in touch with a member of our team to discuss our catalog of products or consult with our experts.