C-Purlins: A Detailed Guide For Construction Professionals (2024)

C-Purlins, also known as cee purlins, are shaped like the letter C and provide structural support for wall and floor beams. In this article, you will learn more about C-Purlins, review a C-Purlin span chart, and compare C-Purlins vs. Z-Purlins.

C-Purlins: A Detailed Guide For Construction Professionals (1)

What are C-Purlins?

A C-Purlin is a type of structural member used in the construction of roofs and walls in steel buildings. It is shaped like a “C” and is used to support the load from the roof deck or wall cladding. C-Purlins are typically made from cold-rolled steel and come in a variety of sizes to suit different building designs. Their versatility, ease of installation, and cost-efficiency make them an attractive option for many builders and architects. Below are some common places where you can find c-purlins:

  1. Residential Construction: C-Purlins support residential homes and other small buildings, where they are used to support the roof deck and wall cladding.
  2. Commercial Construction: C-Purlins see use in larger commercial buildings such as warehouses, factories, and retail centers. They may support the roof deck and wall cladding and can be used in combination with other structural members such as girts and steel beams.
  3. Agricultural Construction: C-Purlins also find frequent use in agricultural buildings such as barns, stables, and sheds, where they support the roof deck and wall cladding.
  4. Prefabricated Structures: Prefabricated structures such as modular buildings, portable buildings, and container structures often use C-Purlins.
  5. Industrial Construction: C-Purlins are used in the construction of industrial buildings such as power plants, oil refineries, and chemical plants.

Red Oxide Purlins vs. Galvanized Purlins

C-Purlins are available in two types of finishes: red oxide (or ‘red iron’) or galvanized. Manufacturers apply these finishes to the supports in order to prevent rusting and other potential damages.

Red oxide purlins are the more simple finish, as it is just a red spray paint primer finish. It does help prevent initial rusting, but will not prevent further rusting when exposed to external weather conditions.

Galvanized purlins are finished with zinc-alloy plating. This helps the material become extremely corrosive resistant, even in tough conditions. Galvanized purlins are popular in chemical plants or coastal environments where oxidization chances are increased.

So, which finish is the better choice? Structurally speaking, neither red oxide nor galvanized finishes provide a particular advantage over the other. Price-wise, there is a significant difference. Red purlins tend to be between 25-35% cheaper when compared to galvanized purlins.

E-houses typically use galvanized purlins which fit with the requirements of the overall structure. Red purlins are more commonly used in commercial buildings.

C-Purlins: A Detailed Guide For Construction Professionals (2)

The C-Purlin Span Chart

A C-Purlin span chart is a table or chart that provides information on the maximum allowable span for a C-Purlin of a given size and gauge (i.e. thickness) when used in a specific load-bearing application. The chart typically includes information such as the size and gauge of the C-Purlin, the type of load (i.e. roof or wall), the spacing of the purlins (i.e. the distance between the supports), and the maximum allowable span in feet or meters.

The values provided in the chart are determined by engineering calculations and testing and are based on the strength and load-bearing capacity of the material, as well as the specific application and conditions in which it will be used. The span chart is used by architects, engineers, and builders to determine the appropriate size and spacing of C-purlins for a given construction project. Below is an example of a common c-purlin span chart:

C-Purlins: A Detailed Guide For Construction Professionals (3)

C-Purlins vs. Z-Purlins

Z-Purlins are another type of horizontal beam that help form the roof and walls of a structure. The name originates from its unique ‘Z’ shape, which helps in overlapping several joints.

Z-Purlins’ ability to connect multiple objects together allows it to be much stronger and structurally sound when compared to c-purlins. Because of this, many large-scale buildings choose Z-Purlins to be their support of choice.

C-Purlins and Z-Purlins can combine with other structural members to create a complete steel framing system. The choice of which type of purlin to use will depend on the specific requirements of the project. This includes the type of load, size and spacing of the purlins, and cost considerations.

C-Purlins: A Detailed Guide For Construction Professionals (4)

Conclusion

C-Purlins serve as an essential element in supporting walls, beams, and flooring of nearly all structures. C-Purlins may span long lengths and provide strong durability. No side drilling and cutting are required to assemble them into a broader metal structure. As such, C-purlins will continue to find frequent industry use long into the future.

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C-Purlins: A Detailed Guide For Construction Professionals (2024)

FAQs

How far can you span an 8 inch C purlin? ›

The sizes are as follows: A four-inch purlin can span 12 feet. A six-inch purlin can span 18 feet. An eight-inch purlin can span 25 feet.

How far apart should C purlins be? ›

How Far Apart Should C Purlins Be Spaced for ultimate structural integrity? It is important to space C purlins correctly for ultimate structural integrity. The minimum spacing is 900 mm (0.9 metres) and the maximum is 1,200 mm (1.2 metres).

Which is stronger, Z purlin or C purlin? ›

Z Purlins are extremely strong and can support heavy structures although, C purlins have relatively less strength. Therefore, in buildings with a bigger roofing or loading capacity, Z purlins would be a better choice. They are commonly used in agricultural and industrial buildings.

What is the purpose of the C purlins? ›

What Is A C Purlin? C purlins, also known as Cee purlins, are in the shape of the letter C and provide structural support for beams required for walls and flooring. In addition to roofing, C purlins are often used for structural support in walls and as floor joists.

Are purlins load bearing? ›

Load Distribution to Supports: Purlins function as load-bearing members, distributing the roof's weight to the supporting structure, which may include columns, beams, or load-bearing walls. Proper engineering and design ensure the loads are allocated efficiently to prevent overloading.

How far can a 150 purlin span? ›

Taking into account industry standards and basic safety recommendations, bridging shall be installed for all 'Z' or 'C' 100 purlins wherever they span more than 2 metres, for all 150 purlins wherever they span more than 3 meters, and for all 200, 250 and 300 purlins wherever they span more than 4 meters.

What is the maximum spacing between purlins? ›

When positioned, roof purlins should be spaced no further than 1.2 metres apart when using sheeting with a thickness of 0.7mm, and 1 metre when using 0.5mm sheeting. Exact requirements will vary, but as a rough guide, this is a good rule of thumb to follow.

What is the standard length of C purlins? ›

C-Purlin Steel Beams are available in typical lengths between 6'-25' (1.83-7.62 m). C-Purlin steel beams are a type of structural steel that is used to support the roof and walls of buildings. They are shaped like the letter "C" and are available in a variety of sizes and thicknesses.

What are the disadvantages of purlins? ›

DISADVANTAGES:
  • The purlins are applied horizontally, not vertically, causing a wavy roof system.
  • The wave of the roof stretches the metal causing screws or nails to pull out.
  • Trusses being 4', 6' or 8' O.C. makes for a good landing pad for the birds to perch themselves on and make a mess of the inside of the building.

What is the alternative to C purlins? ›

Z purlins are somewhat stronger than C purlins due to their interlocking shape. They are typically used at joints and overlaps, giving structure to the roof and wall joists.

What lumber is best for purlins? ›

Kiln-dried softwood is recommended for purlins, girts, or decking (pine, fir, hemlock, and spruce). Hardwoods are difficult to fasten into without splitting and contain acids that are corrosive to metal panels.

What do purlins sit on? ›

Typically, purlins are supported by both rafters or building walls when laid horizontally. With this support, the roof deck can be laid comfortably and safely over the purlins. By 'roof deck', we mean any metal sheeting, plyboard, or wooden panels used to create the surface of the roof.

How to join C purlins together? ›

If you need two purlins together, it is best to place them back to back. And connect them by bolting, not welding. If you need a tube, use a tube rather than making one.

How much does 8 inch C purlin weight per foot? ›

AVALIABLE SIZE
DIMENSION A​DIMENSION BWEIGHT PER LF
6"2-1/2"16G=2.45 LBS 14G=3.06 LBS 12G=4.29 LBS
8"2-1/2"16G=2.45 LBS 14G=3.06 LBS 12G=4.29 LBS
10"3"16G=2.45 LBS 14G=3.06 LBS 12G=4.29 LBS
12"3"14G=4.88 LBS 12G=4.88 LBS
2 more rows

What is the maximum span of purlins? ›

Sleeved purlin system for roofing

It can be used in structures with rafter spacings up to 15m and a roof pitch up to and including 25 degrees. End bay purlins are single span, with double span purlins on internal bays. The maximum span between rafters is 8 metres, therefore maximum double span length is 16 metres.

How far can you span an 8 receiver channel? ›

I use 8" purlin for my end wall rafters and will span them 20-24' knowing that wall will get sheeted. I wouldn t go more than 10 with purlins spaced at 5 maximum. On that 12 roof you can cantilever 2 past the column. I would personally use 8 receivers and purlins just for peace of mind.

Can I use C purlin for floor joists? ›

C section purlins or cee section purlins are designed to form the walls and floor joists of a building shell structure, making them ideal for supporting beams needed for mezzanine flooring.

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