C Purlin vs Z Purlin: The Differences Explained

As far as the construction site of relevant construction projects is concerned, at present, what everyone should know is about the use of building materials in the current construction market.

There is no doubt that the two most widely used building materials are actually Z-section steel purlin and C-section steel purlin.

Two types of building materials, Z-section steel and C-section steel, have been developed and put into use in recent years, and Z-section steel and C-section steel have been widely used in the construction industry shortly after they were introduced because of their low carbon and durability.

In the field of the construction industry now involved, there is a very large amount of data on the use of steel in the specific construction process.

In addition, because the current Z-section steel purlin and C-section steel purlin have greatly replaced the status of some more traditional building materials in a certain sense, in fact, this has created a large number of Z-section steel and C-section steel to a certain extent.

Difference between C purlin and Z purlin

In order to understand the essential difference between C-section steel purlin and Z-section steel purlin, we need to have a corresponding understanding of C/Z section steel purlin

Next, I will tell you about C-section steel purlin and Z-section steel purlin respectively, and then analyze their essential differences according to the understanding of their use.

The angle between C-shaped steel purlin and Z-shaped steel purlin is different.

The included angle of C-shaped steel purlin is 90 degrees, and the included angle of Z-shaped steel purlin is less than 90 degrees, about 60-75 degrees.

Therefore, the included angle of purlin must be considered in the selection and combined with the corresponding stress knowledge.

Compared with Z purlin, the mechanical properties of the strong and weak axes of C purlin are very different

The connection between C-section steel and steel frame usually adopts screw connection, which must be considered as simple support in the calculation, so the latter is more reasonable in stress, calculation results and structure.

Therefore, in addition to other special processing needs such as door and window openings, Z-shaped steel section shall be preferred, and C-shaped steel shall be preferred for wall purlins and house purlins with small slope;

The roof purlin with large slope shall be Z-shaped.

What kind of purlin should be used in what environment? This is crucial for selecting appropriate building materials.

1. Roof slope considerations:

• For low-slope roofs: The section modulus of Z-shaped steel purlins is marginally higher than C-shaped steel purlins, but the difference is not substantial.
• For steep-slope roofs: Z-shaped steel purlins are preferable. As roof pitch increases, the modulus utilization of Z-shaped purlins improves symmetrically in the vertical direction, enhancing their performance and efficiency.

2. Wall applications:

The choice between Z-shaped and C-shaped purlins for wall girts is relatively interchangeable, with minimal performance differences.

3. Continuous structural members:

Z-shaped steel purlins are recommended for continuous spans due to their ease of overlapping, which simplifies installation and improves structural continuity.

Environmental factors influencing purlin selection:

• Corrosive environments (coastal areas, industrial zones):
  Use galvanized or corrosion-resistant coated purlins. Z-shaped purlins may have a slight advantage due to fewer surfaces for moisture accumulation.
• High wind load areas:
  Z-shaped purlins often perform better due to their improved torsional rigidity.
• Seismic zones:
  Both C and Z purlins can be suitable, but the overall building design and local building codes will dictate specific requirements.
• Snow load regions:
  Z-shaped purlins on steeper roofs can help with snow shedding and load distribution.
• Temperature fluctuation zones:
  Consider thermal expansion properties and use appropriate connection details for both types.

While Z-shaped purlins offer specific advantages in certain scenarios, C-shaped purlins remain widely used due to their versatility, ease of manufacture, and familiarity among builders. The choice often depends on specific project requirements, local building codes, and design preferences.

In conclusion, understanding these key differences between C and Z steel purlins enables informed decision-making in structural design. Always consult with a structural engineer and adhere to local building codes when selecting and implementing purlin systems.

C purlin

C-section steel is automatically processed and formed by C-section steel forming machine.

The machine can automatically complete the forming process according to the given size.

C-section steel is processed by hot coil cold bending, with thin wall, lightweight, excellent section performance and high strength.

Compared with traditional channel steel, the same strength can save 30% of materials.

Application of C-section steel

C-section steel, also known as C-channel or C-profile, is a versatile structural element widely utilized in the construction of steel-framed buildings. Its primary applications include purlins and wall girts, where it provides excellent load-bearing capacity and ease of installation. The C-shaped cross-section offers high strength-to-weight ratio, making it ideal for lightweight roof trusses, brackets, and various other building components.

In steel structure design, C-section profiles can be efficiently combined to create composite members with enhanced structural performance. For instance, back-to-back C-sections can form box beams with increased load-carrying capacity and torsional rigidity. This adaptability allows architects and engineers to optimize material usage while meeting specific design requirements.

Beyond construction, C-section steel finds extensive use in mechanical and light industrial manufacturing. Its applications include support columns for conveyor systems, machine frames, and cantilever arms for equipment mounting. The profile’s inherent stiffness and ease of fabrication make it a cost-effective solution for various industrial structures and fixtures.

Moreover, the standardized dimensions and wide availability of C-section steel facilitate modular design approaches, enabling rapid assembly and potential future modifications in both construction and industrial settings.

Processing flow of C purlin

Discharging ① – leveling ② – forming ③ – setting ④ – straightening ⑤ – length measurement ⑥ – punching the round hole of tie bar ⑦ – punching the elliptical connecting hole ⑧ – forming and cutting ⑨

Specification type

C-shaped steel purlins are divided into five specifications: 80, 100, 120, 140 and 160 according to different heights.

The length can be determined according to the engineering design, but considering the conditions such as transportation and installation, the total length is generally no more than 12m.

C purlin weight chart

Meaning of numbers in each line (take C80×40×20×2.5 as an example):

• Section height h=80mm；
• Section width b=40mm；
• Crimping width c=20mm；
• Thickness t=2.5mm；

C purlin weight calculator

Z Purlin

Z-section steel is a widely used cold-formed thin-walled structural element, characterized by its distinctive Z-shaped cross-section. Typically manufactured with thicknesses ranging from 1.6mm to 3.0mm and section heights varying between 120mm and 350mm, Z purlins offer an excellent strength-to-weight ratio for various structural applications.

The primary materials used in Z purlin production are hot-rolled steel (which may be painted for corrosion protection) and galvanized steel. The latter provides superior corrosion resistance, making it particularly suitable for exposed or high-humidity environments.

Manufacturing processes and quality standards for Z purlins in China adhere to the GB50018-2002 specification, which outlines requirements for cold-formed thin-walled steel structures. This standard ensures consistent quality, dimensional accuracy, and structural integrity across different manufacturers.

Z-section steel finds extensive application in large-scale steel structure facilities, such as industrial warehouses, commercial buildings, and agricultural structures. Its design allows for efficient load transfer and easy installation, contributing to reduced construction time and costs.

Custom fabrication of Z purlins is common practice, with lengths and hole patterns tailored to specific project requirements. Advanced CNC machinery enables precise cutting, punching, and forming operations, ensuring that each purlin meets exact specifications for optimal performance in its intended application.

Applications of Z-section steel purlin

Cold-formed Z-shaped steel profiles offer significant advantages, including customizable specifications, versatile sizing options, and exceptional compressive strength-to-weight ratios. These characteristics make Z-section purlins highly adaptable for a wide range of industrial and construction applications.

Z-section purlins find extensive use across various sectors, including:

Construction and Infrastructure:

• Building steel structures (roofing and wall systems)
• Highway guardrails and bridge components
• Steel sheet piling for soil retention
• Cable-stayed bridge elements
• Scaffolding and formwork systems
• Municipal construction projects

Transportation:

• Automotive frame and body components
• Railway vehicle structural elements
• Container reinforcement and framing

Energy and Utilities:

• Power transmission tower support structures
• Solar panel mounting systems
• Pipe supports for industrial applications

Agriculture:

• Greenhouse structural framing
• Agricultural machinery components

Industrial and Commercial:

• Shelving and racking systems
• Electrical cabinet framing
• Furniture structural elements
• Storage facility construction

Specialized Applications:

• Shipbuilding structural components
• Guide rail systems for material handling
• Keel steel for small watercraft
• Door and window framing in buildings

The versatility of Z-section purlins, combined with their high strength-to-weight ratio and corrosion resistance (when galvanized), makes them an ideal choice for engineers and designers seeking efficient, cost-effective structural solutions across a diverse range of industries and applications.

Z purlin weight chart

Z purlin weight calculator