When it comes to building frameworks, supports, posts, and custom fabrication, choosing the right steel section is critical. The profile you select affects everything from load capacity and rigidity to ease of welding, finish quality, and overall project cost.
Among the most popular structural options, RHS steel (Rectangular Hollow Section) stands out as a go-to choice across both residential and commercial construction—and for good reason. Its rectangular shape offers excellent strength, clean lines, and practical flat faces that make fabrication easier and more precise.
In this guide, we’ll break down what RHS steel is, why it performs so well in structural and fabrication work, and where it’s most commonly used.
What is RHS Steel?
RHS (Rectangular Hollow Section) is a hollow steel profile with a rectangular cross-section, manufactured from cold-formed or hot-rolled steel. It’s widely used in structural steelwork because it offers a strong, stable shape with excellent versatility.
RHS steel is known for its:
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Clean lines and sharp, modern appearance
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Smooth, flat surfaces that are easy to mount, weld, or bolt to
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Consistent dimensions for accurate fabrication and repeat builds
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Excellent strength-to-weight ratio (strong without being overly heavy)
Because RHS comes in a wide range of sizes, wall thicknesses, lengths, and grades, it suits everything from light fabrication to heavy structural support.
In Australia, RHS is commonly supplied to AS/NZS 1163, which is a key standard for structural steel hollow sections used in building and engineering applications.
Benefits of RHS Steel for Structural and Fabrication Projects
RHS steel (Rectangular Hollow Section) is one of the most practical and widely used steel profiles for a reason: it combines high structural performance with fabrication-friendly geometry. Whether you’re building a structural frame, a support system, or a custom metal project, RHS delivers strength and efficiency without unnecessary bulk.
1) 🏗️ High Structural Strength (Great Load Capacity in a Compact Profile)
RHS profiles offer excellent load-bearing performance because of their closed, hollow shape. Unlike open sections, a rectangular hollow section distributes material around the outside of the profile, which improves stiffness and helps the member resist bending and twisting under load.
That makes RHS a strong choice for:
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Vertical columns (posts and uprights that carry weight downward)
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Horizontal beams (supporting spans and distributing loads)
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Framing systems (walls, roof structures, platforms, bracing frames)
Another major advantage is the geometry: RHS has flat faces and 90° corners, which makes it easier to:
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line up clean joins
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weld plates and brackets neatly
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bolt through with accurate hole placement
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build square frames with consistent angles
✅ Why it matters: Strong load capacity + flat surfaces = a section that’s both structurally reliable and easy to connect in real-world construction.
2) 🔧 Versatility in Design & Fabrication (Easy to Work With)
RHS steel is popular with fabricators because it’s straightforward to work on—both in workshops and on-site. It can be easily:
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cut to precise lengths
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drilled for bolts, brackets, and fixings
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welded for strong structural joins
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coated or galvanised for corrosion resistance
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painted or powder-coated for architectural finish
That makes RHS ideal for both standard construction jobs and custom builds where you need flexibility, including:
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industrial frames and supports
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gates, platforms, and equipment frames
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pergolas, carports, awnings, and posts
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architectural features where clean lines matter
✅ Why it matters: You can use RHS for utility builds or high-visibility projects without switching to a different profile—just change the finish and thickness.
3) 📦 Efficient Material Usage (Strength Without Excess Weight)
RHS steel is also efficient from a design and cost standpoint. Because strength in bending and stiffness are strongly influenced by where the material sits in the cross-section, hollow sections often achieve high performance without needing a solid, heavy core.
In practical terms, RHS can deliver strong performance while using material efficiently compared to some solid bars or heavier profiles.
This often translates to:
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lower material costs (depending on size/spec)
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easier handling on site (less weight per member)
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reduced transport weight and simpler logistics
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faster installation, especially when multiple lengths are being used
📌 Practical takeaway: RHS helps you build strong frames that are easier to move, position, and install—without sacrificing rigidity.
4) 🛡️ Corrosion Resistance Options (Built for Indoor and Outdoor Use)
One of the biggest advantages of RHS steel is how easily it can be matched to different environments. Whether your project is indoors, exposed to weather, or located in a high-corrosion zone, RHS can be supplied with finishes that help protect against rust and extend service life.
RHS steel is commonly available as:
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Black steel (untreated)
Ideal for fabrication and welding where you plan to apply your own protection afterward. Black RHS is often used for indoor frames, workshop builds, and projects that will be painted, powder-coated, or sealed after installation. -
Pre-galvanised steel
Zinc-coated during production, making it a practical choice for light outdoor exposure or projects where basic corrosion resistance is needed without full hot-dip galvanising. It’s commonly used for fencing and general fabrication where conditions aren’t extreme. -
Hot-dip galvanised RHS
The most durable option for corrosion protection. Hot-dip galvanising coats the steel in a thick zinc layer, making it ideal for outdoor installations, wet environments, and areas exposed to humidity or salt air (including coastal regions).
✅ Why this matters: With the right finish, RHS can handle everything from indoor structural framing to fully exposed outdoor steelwork—without premature corrosion becoming the weak point of the build.
5) ✨ Aesthetic Appeal (Clean Lines for Modern Builds)
RHS isn’t just strong—it also looks sharp. The rectangular profile has a clean, modern feel that suits contemporary design, which is why it’s a favourite in architectural and high-visibility projects.
The straight edges and crisp angles make it easy to create clean joins, symmetrical layouts, and a premium finish—especially when paired with powder coating or paint.
RHS is commonly used in architectural applications such as:
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Balustrades and handrails
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Feature steelwork (decorative frames, entry statements, pergola structures)
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Modern fences and privacy screens
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Exposed structural elements in residential and commercial buildings
📌 Design advantage: Because RHS has flat faces, it also works well with panels, timber cladding, brackets, and fixings—making it easier to achieve a clean, professional look without awkward mounting points.
Common Applications of RHS Steel
RHS steel is used across construction and fabrication because it offers high strength, clean lines, and easy fabrication. Its flat faces make it simple to weld, bolt, and align—making it a practical choice for both structural builds and custom projects.
| Application | Why RHS Works Well |
|---|---|
| Structural frames | High strength and rigidity for reliable load support |
| Fencing & gates | Lightweight, durable, and easy to fabricate with clean lines |
| Machinery frames | Flat faces make alignment, mounting, and welding straightforward |
| Furniture & fixtures | Modern, square-edged look with strong form and finish |
| Trailer fabrication | Strong with good impact resistance and structural stiffness |
| Agricultural sheds | Galvanised options available for long-term outdoor durability |
RHS vs SHS vs CHS – What’s the Difference?
While RHS is one of the most popular steel profiles, it’s often compared with SHS and CHS depending on how the steel will be loaded and how it needs to look.
| Profile | Shape | Best For |
|---|---|---|
| RHS | Rectangular | Beams, frames, fencing, structural members needing flat faces |
| SHS | Square | Balanced load handling in all directions (posts, frames, general structural use) |
| CHS | Circular | Columns, round posts, handrails, and fluid flow applications |
📌 Quick takeaway: RHS is often preferred when flat surfaces and directional strength matter—especially for horizontal beams, frames, and posts where mounting and clean connections are important.
Tips for Choosing RHS Steel
To get the best performance and lifespan from RHS steel, keep these practical selection tips in mind:
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Match the steel grade (e.g., C350, C250) to the load and structural requirements
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Choose galvanised RHS for outdoor builds or corrosion-prone environments
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For visible architectural projects, consider pre-galv or powder-coated RHS for a cleaner finish
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Always buy from suppliers who meet AS/NZS 1163 structural steel standards
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Confirm wall thickness suits the application (don’t under-spec for load-bearing work)
Final Thoughts
Whether you’re building a shed, fabricating a frame, or designing a modern fence, RHS steel is a top-tier choice. It delivers an excellent balance of strength, workability, and appearance, which is why it remains one of the most widely used steel profiles across Australia.
Need RHS Steel for Your Next Project?
Looking for premium-quality RHS steel backed by local expertise and fast delivery? Super Steel Australia supplies structural-grade RHS steel in a wide range of sizes, thicknesses, and coatings—ideal for builders, fabricators, and contractors.
👉 Contact Super Steel Australia today to get a quote, expert advice, or custom cutting services for your project: https://supersteelaust.com.au/