Metal Purlins

Introduction Metal purlins are the silent workhorses in structural steel construction. Acting as secondary framing members, they run across the primary frames and provide support for wall and roof sheeting. Essential in everything from warehouses to barns, metal purlins offer unmatched strength, durability, and efficiency. In this blog, we dive deep into the materials, profiles, sizes, and use cases that define the world of metal purlins. Whether you're in construction, manufacturing, or engineering, this guide is your reference point for making the right choice.

What Are Metal Purlins? Purlins are horizontal beams that form part of the roof or wall support structure in buildings. Unlike timber purlins, metal purlins offer superior strength, are fire-resistant, and require little maintenance. They provide structural support by distributing loads from the sheeting to the primary framing members. Their adaptability and longevity make them a staple in modern construction practices.

Common Materials Used in Metal Purlins

1. Galvanized Steel
   • Most widely used.
   • Zinc-coated for corrosion resistance (e.g., G90 or Z275).
   • Yield strength: 40–55 KSI.
2. Galvalume Steel
   • Aluminum-zinc alloy coating.
   • Superior corrosion resistance—ideal for coastal and industrial settings.
3. Cold-Rolled Steel
   • Tight tolerances.
   • High strength and precision.
4. Stainless Steel & Aluminum
   • For marine, chemical, or specialty buildings.

Purlin Profiles Explained

1. C Purlins
   • C-shaped with flanges on one side.
   • Commonly used on walls or simple-span roofs.
   • Easier to bolt and connect.
2. Z Purlins
   • Z-shaped cross-section.
   • Laps over each other—stronger for longer spans.
   • Ideal for roofing.
3. Sigma Purlins
   • Less common.
   • Enhanced strength for heavy-duty use.

Each profile’s geometry affects load-bearing, installation speed, and application. Z purlins, for example, allow for better lap joints, distributing loads more efficiently over longer spans.

Purlin Sizes and Thicknesses

• Standard Widths: 100mm, 120mm, 150mm, 200mm, 250mm, 300mm
• Thickness Range: 1.2mm to 3.0mm
• Lengths: Custom-cut, usually 6m to 12m

Applications Across Industries

• Commercial: Warehouses, shopping malls.
• Industrial: Factories, refineries, workshops.
• Agricultural: Barns, poultry sheds, greenhouses.
• Residential: Carports, garages.
• Infrastructure: Airports, stadiums, bus terminals.

For example, industrial buildings in the UAE often use Z purlins for their ability to span wide roof sections with minimal supports.

Advantages of Using Metal Purlins

• High strength-to-weight ratio.
• Supports long spans with minimal sagging.
• Cost-efficient for large projects.
• Easy to install and transport.
• Resistant to fire, rot, pests.

Design Considerations and Load Calculations

Key design elements:

• Span length
• Live and dead loads
• Wind and seismic forces
• Purlin spacing

Engineering software like STAAD.Pro and Tekla Structures assist in accurate sizing and analysis. Ensure compliance with building codes such as IBC, AS/NZS 4600, or Eurocode 3.

Coatings and Surface Treatments

• Hot-Dip Galvanizing: Common for outdoor applications.
• Pre-painted Steel (PPGI): Aesthetic and corrosion-resistant.
• Powder Coating: Optional, for enhanced appearance and protection.
• Galvalume Coating: Ideal for aggressive environments.

FAQs About Metal Purlins

Q1: Can metal purlins be reused? Yes, especially if they’re undamaged—commonly seen in modular buildings.

Q2: What is the best profile for long spans? Z purlins, due to overlapping ability and superior strength.

Q3: Are purlins load-bearing? They are secondary load-bearing members, transferring loads to main frames.

Q4: Do purlins require bracing? Yes, particularly in high-wind or seismic areas. Sag rods and bridging are used.

Q5: What gauge is commonly used? Ranges from 14 to 18 gauge (1.2 mm to 2.5 mm).

Conclusion: How to Choose the Right Purlin

When selecting a purlin, consider the span, load type, profile shape, and environmental exposure. C purlins are great for straightforward installs, while Z purlins offer flexibility and span efficiency. Sigma purlins serve high-load or multi-story structures.

Work closely with your structural engineer and purlin supplier—like Machine Matcher—to ensure your building gets the most optimized solution. We help match your requirements with the right machines or suppliers globally.

Whether you’re building in the UAE, UK, USA, or beyond, understanding purlin specs can significantly impact the durability and cost-efficiency of your structure. Choose wisely, and your project will thank you in both stability and savings.

Major U.S. Metal Purlin Manufacturers & Suppliers

1. Western States Metal Roofing

• Overview: Offers galvanized and red prime painted Cee and Zee purlins with immediate availability and nationwide delivery.

• Products: Cee & Zee purlins in 12, 14, and 16 gauge; sizes ranging from 4" to 12".

• Website: westernstatesmetalroofing.com

2. MBCI (Metal Building Components Inc.)

• Overview: Provides a comprehensive range of interlocking Cee and Zee purlins designed for structural integrity and aesthetic appeal.

• Products: Available in 12, 13, 14, and 16 gauge; red oxide or G90 galvanized finishes; various sizes with standard and custom punching patterns.

• Website: mbci.commcelroymetal.com

3. McElroy Metal

• Overview: Manufactures an extensive line of cold-formed substructural components, including Cees, Zees, and Eave Struts.

• Products: Offers components in red oxide and G90 galvanized finishes, with standard and custom punching options.

• Website: mcelroymetal.com

4. Eagle National Steel

• Overview: Supplies high-quality steel C and Z purlins with options for custom cutting and punching.

• Products: Various sizes in 14-gauge thickness; lengths up to 40 feet.

• Website: eaglesteel.com

5. Wheeler Metals

• Overview: Offers a variety of steel products, including Cee purlins, with locations in Oklahoma, Arkansas, and Missouri.

• Products: Cee purlins in sizes from 3" x 1½" to 10" x 2¾".

• Website: wheelermetals.com

6. JNL Steel Components, Inc.

• Overview: Specializes in manufacturing purlins in both standard and custom lengths to optimize builders’ efficiency.

• Products: Offers a broad selection of standard tubing and custom purlin options.

• Website: jnlsteel.com

7. Vitz Metals

• Overview: Stocks a large inventory of steel and roof purlins, essential for completing steel building or roofing projects.

• Products: C and Z purlins in 14 gauge, 40 ksi; lengths from 15 to 30 feet.

• Website: vitzmetals.com

8. 380 Steel & Pipe Supply

• Overview: Provides a diverse selection of metal purlins, crucial for constructing durable roofing and structural systems.

• Products: Red prime purlins in various sizes and shapes; custom cutting and fabrication services available.

• Website: 380steel.com

9. The Purlin Mill

• Overview: Specializes in manufacturing purlins and girts for the pre-engineered steel building market in Oregon.

• Products: Offers a range of purlin products tailored to the pre-engineered building sector.

• Website: thepurlinmill.com

10. Metroll USA

• Overview: Part of a global network, Metroll offers a wide variety of metal buildings and components, including purlins.

• Products: Factory-direct C and Z purlins; custom design services available.

• Website: metroll.us