When it comes to steel roofing systems, structural support is one of the most important factors. Among the many components used, the c purlin plays a key role in holding up the roof and making sure the building stays strong and stable. In this article, we’ll explain what a c purlin is, its main benefits, load capacity, and how it’s commonly used in modern construction.
What Is a C Purlin?
A C purlin is a horizontal steel beam shaped like the letter “C” when viewed from the end. It is mainly used in steel construction to support roof sheets and wall cladding. Made from high-strength steel, C purlins are lightweight but strong, making them ideal for various building projects.
They usually come in a galvanised or red oxide finish, both of which help to protect the metal from rust and corrosion over time. Now, new material coatings like ZM310 (a zinc-magnesium alloy coating with 310g/m² mass) offer even better corrosion resistance and durability, making them ideal for outdoor or coastal projects.
What Are the Benefits of Using C Purlins for Steel Roofing Systems?
There are many reasons why C purlins are widely used in steel roofing systems:
1. Strong but Lightweight
Despite being lighter than other support beams, C purlins offer great strength and can carry heavy roof loads without bending.
2. Easy to Install
Thanks to their shape and straightness, C purlins are simple to install. They don’t usually need much drilling or cutting, which saves time on-site.
3. Cost-Effective
Because they are easier to handle and transport, C purlins are more affordable than heavier steel beams, especially for small- to medium-scale projects.
4. Corrosion-Resistant
When galvanised, C purlins are well protected against rust and weather damage, making them ideal for long-term use. Purlins with ZM310 coating further improve rust resistance and are now part of Swan Swee’s updated product line.
Understanding Load Capacity
C purlins help transfer the load from the roof sheets to the main structural frame. They are best suited for short to medium spans and are strong enough to support standard roofing and cladding materials.
However, the actual load capacity depends on factors such as the size, thickness, and spacing of the purlins. That’s why it’s always best to consult a structural engineer for proper planning.
With the introduction of purlins featuring ZM310 coating, Swan Swee now offers models like C15019 (150 mm web, 1.9 mm thick), C22524 (225 mm web, 2.4 mm thick), and C35030 (350 mm web, 3.0 mm thick), providing engineers with more consistent and durable options.
Where Are C Purlins Commonly Used?
C purlins are highly versatile and can be found in many types of buildings:
- Roofing Structures: Used as part of the secondary framing system to support metal roof sheets.
- Wall Framing: Acts as horizontal supports in wall cladding systems.
- Floor Joists: Suitable for supporting light floor loads.
- Industrial & Residential Buildings: Common in warehouses, garages, verandahs, and small commercial units.
C Purlins vs Z Purlins
Both C and Z purlins are used in roofing, but there are some differences:
- Shape: Z purlins have an angled shape that allows overlapping, which gives added strength.
- Load: Z purlins can span longer distances and handle heavier loads.
- Installation: C purlins are simpler to install and often used when overlapping isn’t needed.
Things to Consider When Choosing C Purlins
When selecting C purlins for your project, consider the following:
- Size: Common sizes range from 75 mm to 350 mm in depth. Swan Swee’s latest catalogue offers different sizes under the ZM310 coatings for added flexibility.
- Spacing: Depends on the weight of the roof and wind loads.
- Finish: Choose galvanised for longer life or red oxide if painting will be applied later.
For improved weather resistance, purlins with ZM310 coatings are now a strong alternative.
Installation Tips
For best results, follow these practices:
- Fix purlins using proper brackets and bolts.
- Avoid cutting them on-site as it can weaken the steel and lead to rust.
- Store purlins in dry conditions to prevent early corrosion. Swan Swee also offers pre-punched hole options, including round holes (Ø14mm, Ø18mm) and slotted holes (14x22mm, 18x22mm), customisable based on your design requirements. Holes can be placed on the web, flange, or lip depending on your build.
Are C Purlins Worth the Cost?
Yes. C purlins offer great value for money. They are strong, easy to work with, and more affordable than other structural materials. Galvanised purlins may cost slightly more upfront, but they last much longer and require less maintenance.
Why Choose Swan Swee Construction for Your C Purlin Needs
At Swan Swee Construction, we supply high-quality c purlins that offer excellent strength and durability—perfect for modern steel roofing systems. With over 30 years of experience in steel construction across Singapore and Malaysia, we understand the importance of choosing the right materials for your building needs.
Our newly introduced ZM310 material coatings enhance corrosion resistance and meet today’s higher structural demands. Whether you’re working on a warehouse, workshop, or residential property, our team can guide you in selecting the best c purlin for your project’s load and span requirements.
We also offer a range of standard C and Z purlin sizes, with flexible punching options to suit your design needs. Trust Swan Swee Construction for reliable, long-lasting structural solutions that meet today’s building standards.