Purlin sheds vs structural steel

17 August

Purlin sheds vs structural steel: what you need to know

Structural steel comes out on top for strength and durability.

When you’re building a new shed, one of the main things to take into consideration is the longevity of the structure. One of the main components of your shed – the steel – is one place that you don’t want to cut corners.

Choosing strong, durable materials may cost a little more initially but will save you in the long run, and that’s why we only use Australian structural steel. Here’s a breakdown of the differences between steel vs purlin sheds and why structural steel is the clear winner.

Strength and durability

The purlins typically used in cheaper shed construction are made by cold roll-forming lightweight steel sheets into the desired C or Z shape.

Often, the steel used to manufacture purlins is only 1mm – 3mm millimetres thick, making it much more flimsy and prone to bend and twist. This means purlin structures typically aren’t suitable for heavy-duty applications like storing machinery or industrial sheds. A minor bump or two and your shed could suffer damage that’s difficult to fix. Lots of bracing is required to get a requisite level of strength, but it still doesn’t compare to the rigidity of structural steel.

A structural steel shed is made from hot-formed RHS steel members in H or I beam shapes. These universal steel beams can be up to 20mm thick and are welded and fabricated to order, as well as being hot-dip galvanized for corrosion resistance and durability.

Structural steel members and welded trusses are intrinsically stronger, making them more suited to large spans and bigger structures, whereas purlins simply don’t have the same structural integrity.

Installation time

Although it would seem like purlin sheds are quicker and easier to install, they can actually take considerably longer to install as every piece has to be individually bolted together on site. The roll-formed sections need to be bolted to angle brackets and then bolted to the slab, meaning lots of labour time for the installation crew.

Plus, because the pieces are quite flimsy and flexible, they present their own installation challenges.

Contrast this with structural steel members that are engineered to the precise size required, and fabricated so that they can simply be erected on site. The prefabricated welded columns and trusses arrive ready to go and simply need to be lifted into place. The installation process still takes time of course, but is generally much faster than purlin construction.

The ability to customise your shed

Choosing structural steel means that you have the utmost control over the size and shape of your structure. Because each component is cut and welded to order, the possibilities are nearly endless, whereas purlin sheds must be made from standard material sizes.

Additionally, purlins can really only be used up to about a 20 metre span, making them no good for larger industrial structures and commercial buildings. Structural steel spans can be much larger, meaning you can build a shed that works for you today and into the future, allowing for growth and changes in your business.

Safety and approvals

If your site is in a high wind area, a purlin shed may not pass through the approval process as its limited structural strength makes it unsuitable for windy conditions. The larger the shed, the more obvious this issue becomes, so if you’re located in an area that requires a high wind rating a structural steel shed is the way to go.

Conclusion: structural steel is the clear winner over purlin

Whilst purlins are sometimes more cost-efficient for small backyard sheds, once you get into the commercial and agricultural structure space where larger sheds are commonplace, structural steel is the only sensible choice. It’s strong and robust, can be customised to your needs, and presents a lower labour cost due to its faster installation time.

An Australian Made Steelcorp structural steel shed will provide you with the durability, design freedom and strength necessary for your commercial shed project. Give our friendly team a call for advice – we’re here to help.

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