What Is a Portal Frame and Is It Best for Your Shed?

Investing in a large new shed is a significant decision, and understanding the core structure is crucial. A portal frame is a highly efficient and popular design for large-scale buildings, but it's important to know how it works and what materials are best for its construction.

This article explains what a portal frame is, its key components, and its main advantages. We also compare the two main material options: structural steel and roll-formed steel. This helps you decide which is the right choice for your needs.

What is a portal frame? Summary of contents (TL;DR)

• What It Is: A portal frame is a structure with two vertical columns connected by horizontal rafters, creating a clear, open space without internal supports.

• Key Advantages: Portal frames offer large clearspans, cost-effectiveness, fast prefabricated construction, and excellent strength and durability.

• Best Material: For large agricultural, industrial, or commercial sheds (over 300 square metres), structural steel is far superior to roll-formed steel due to its strength, durability, and ability to support additional weight.

• Main Benefit: The primary advantage is maximising usable internal space, which is essential for storing large machinery and optimising workflow.

What Are the Key Components of a Portal Frame?

A portal frame is an assembly of several critical components that work together to create a strong, stable structure.

• Pier Footing: Vertical piers are bored into the ground beneath the columns. These include a cast-in bolt cage that securely anchors the columns.

• Columns: These are the vertical supports that run from the foundation to the rafters, supporting the roof and walls.

• Rafters/Truss: Rafters/trusses span from the apex to the columns, creating the frame for the roof.

• Apex Joint: This is the highest point of the building, where the rafters are joined together with a plate or bracket.

• Haunch Joint: The haunch is the crucial connection point between the top of the columns and the start of the rafters.

• Purlins: A cold-rolled member that runs horizontally between rafters to provide support for the roof cladding.

• Girts: A cold-rolled member that runs horizontally along the outside of the columns, providing a framework to attach the wall cladding.

What Are the Main Advantages of a Portal Frame Shed?

Portal frames are one of the most popular and effective construction methods for large buildings for several key reasons.

Large, Unobstructed Clearspans

The primary benefit of a portal frame is the ability to create a massive open space inside your shed. The frame is fully self-supporting, eliminating the need for internal columns. This maximises usable floor space, which is vital for storing large machinery, optimising layouts, and ensuring efficient movement.

Cost-Effective Construction

Portal frames are a cost-effective building method because they use structural members efficiently to span the width of the building. With a structural frame from Standwell you can efficiently span up to 60m without centre supports.

Efficient Prefabricated Assembly

With a portal frame, structural steel elements can be prefabricated off-site. Because components are welded and bolted together in advance, on-site assembly is significantly faster and easier. For even quicker construction, pre-designed Durakit sheds are available in under four weeks.

Superior Strength and Durability

Portal frames are exceptionally strong and durable, especially when constructed with structural steel. This makes them perfectly suited for large-scale sheds in demanding agricultural, commercial, and industrial environments. For areas with extreme weather, we also manufacture cyclone-rated sheds with fully fabricated steel frames designed to withstand the harshest storms.

Structural Steel vs Roll-Formed Steel for Portal Frames

The material used for your portal frame is the most critical factor in its strength and longevity. While both roll-formed and structural steel can be used, they are suited for very different applications. Generally, roll-formed steel is best for smaller domestic buildings, while structural steel is essential for large sheds.

Why Choose a Structural Steel Portal Frame for a Large Shed?

For any shed larger than 360 square metres, structural steel is the superior choice. Its thickness (5mm to 20mm) makes it far stronger than roll-formed steel, allowing it to support significant additional weight from features like gantry cranes or solar panels. Structural steel frames can also achieve clear spans of over 60 metres without centre supports, which is far more practical for large-scale operations.

In a busy agricultural or industrial environment, a shed frame is exposed to bumps and knocks from heavy machinery. A structural steel frame is far more robust and resistant to damage than a cold-rolled frame. It is also more resilient in harsh Australian weather conditions.

Because structural steel elements are cut and welded to your specific requirements, you have endless options for the design, size, and shape of your building.

How to Plan Your Ideal Portal Frame Shed

We specialise in large structural steel buildings engineered to Australian standards. Our portal frames feature hot-dip galvanised steel, a 25-year guarantee, and premium COLORBOND® and Zincalume® cladding.

If you are planning a large-scale shed project and need a reliable, customisable solution, a structural steel portal frame is the ideal foundation. To see our range of designs and optional features, you can explore our complete building solutions brochure.

Structural Steel Sheds Australia

• Portal frames with clear spans up to 60 metres.
• 25-year guarantee.
• Engineered to Australian building standards.
• Hot dip galvanised steel protective coating. 
• Fabricated structural steel construction. 
• COLORBOND® and Zincalume® cladding. 
• Customisable designs with a range of optional features. 

If you’re looking for a reliable shed, contact us to request a quote today. Alternatively, download our Complete Building Solutions brochure to learn more about our range and explore the possibilities.