Your Complete Reference for RHS Dimensions and Applications
Rectangular Hollow Sections (RHS) give builders the ideal balance of directional strength, clean lines, and fabrication ease for beams, lintels, and horizontal spans. Unlike square SHS (equal sides), RHS have unequal width/height dimensions that concentrate strength along the longer face, perfect for spanning gaps without excess weight. Melsteel stocks primed and galvanised RHS across Melbourne in standard 6.5m or 8m lengths, with custom cutting available.
Standard RHS Sizes Available from Melsteel
RHS sizes follow Australian standards AS/NZS 1163, specified as Width x Height x Wall Thickness (e.g., 100x50x3.0). Here’s the comprehensive range typically stocked:
| Width x Height (mm) | Common Wall Thicknesses (mm) | Best Applications |
|---|---|---|
| 50×25 | 1.6, 2.0, 3.0 | Light frames, furniture, brackets |
| 75×50 | 2.0, 3.0, 4.0 | Pergola beams, small lintels |
| 100×50 | 2.0, 3.0, 4.0, 5.0 | Roof trusses, carport rafters |
| 100×75 | 3.0, 4.0, 5.0 | Medium spans, wall headers |
| 125×75 | 3.0, 4.0, 5.0, 6.0 | Garage beams, light industrial |
| 150×75 | 4.0, 5.0, 6.0 | Longer spans, shed portals |
| 150×100 | 4.0, 5.0, 6.0, 8.0 | Commercial lintels, frames |
| 200×100 | 5.0, 6.0, 8.0 | Heavy-duty trusses, bridges |
| 250×150 | 6.0, 8.0, 10.0 | Large industrial spans |
Larger custom sizes (e.g., 300×200) available on request for engineered projects.
Choosing the Right RHS Size for Your Project
Light-duty (DIY/Home): 50×25 or 75×50 with 2.0-3.0mm walls suit gates, pergolas, and shade sails where aesthetics matter.
Medium-duty (Residential): 100×50 to 125×75 with 3.0-5.0mm walls, handle carports, verandahs, and extensions, strong enough for typical spans up to 6m.
Heavy-duty (Commercial): 150×100+ with 6.0mm+ walls for warehouses, factories, and load-bearing beams where deflection must be minimised.
Key tip: The taller face (height) usually goes vertical for maximum bending resistance. Match wall thickness to your span and load calculations.
Finishes: Primed vs Galvanised RHS
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Primed RHS: Red oxide primer for indoor/welded applications. Cost-effective for further fabrication (see processing services).
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Galvanised RHS: Zinc-coated for outdoor/coastal use (galvanising benefits). No painting needed; ideal for fences, exposed beams.
Both available across all sizes, Melsteel can advise based on your environment and build method.
Melsteel’s RHS Services: From Stock to Site
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Immediate availability in popular sizes, cut to exact lengths (view primed RHS)
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Precision processing: Drilling, notching, and mitre cutting for frames (steel fabrication)
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Custom fabrication: Welded assemblies, brackets, and portal frames
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Melbourne delivery: Crane trucks for direct placement (delivery info)
Browse Melsteel RHS online, download the latest price list, or send drawings via Contact Us.
Need help picking the right size? Call 03 8794 3100, our team matches RHS to your spans, loads, and budget.
FAQs: RHS Sizes and Selection
1. What’s the most popular RHS size?
100x50x3.0 and 150x100x5.0 cover 80% of residential/commercial needs.
2. How do I know what thickness I need?
Thicker walls (4.0mm+) for longer spans/heavier loads; 2.0-3.0mm for light frames (load tables).
3. Can you cut RHS to custom lengths?
Yes, order 50mm increments from Melsteel’s in-house saws.
4. Primed or galvanised for outdoor use?
Galvanised lasts longer without maintenance (coastal steel guide).
Where to Next
SHS vs RHS: Clearing the Confusion
Square Hollow Sections Guide
Steel Angles vs SHS Myths