Rectangular Hollow Sections vs SHS Steel: What Are the Differences, and Which Should You Use?
Choosing between rectangular hollow sections (RHS) and square hollow section (SHS) steel is a common decision for builders, fabricators, and tradespeople across Sydney and NSW. This article explains the key differences and when each section type is the right choice.
Both RHS and SHS are hollow steel tubes manufactured to AS/NZS 1163. They look similar, but their shapes serve different structural purposes. Knowing which to specify can save time, material, and money on your next project.
What Is the Difference Between RHS and SHS Steel?
RHS and SHS are both hollow structural steel sections, but they differ in one fundamental way: their cross-sectional shape.
Shape: RHS is rectangular with unequal sides. SHS is square with equal sides.
Load direction: RHS suits loads along one axis. SHS distributes loads evenly in all directions.
Common uses: RHS is used for carpentry, trailers, and lintels. SHS suits posts, columns, gates, and furniture.
Size example: RHS: 100 x 50 x 3 mm. SHS: 75 x 75 x 3 mm.
Standard: Both meet AS/NZS 1163.
Rectangular hollow sections have two different side dimensions, such as 100 x 50 mm. An SHS has equal sides, such as 75 x 75 mm. Both are manufactured in grades C250L0 and C350L0, making them suitable for structural applications.
Note that many in the trade use "RHS" as a catch-all for any box section. Technically, a 50 x 50 section is SHS, not RHS. Getting this right matters when ordering from a steel supplier.
Which Section Should You Use for Your Project?
When to Choose RHS
RHS is the better option when a member needs to resist bending loads along one primary axis. Its taller profile gives greater strength and stiffness in the vertical direction.
Common applications of rectangular hollow sections include:
▸Structural carpentry for sheds, mezzanines, and residential builds.
▸Trailer and truck body construction carrying significant horizontal loads.
▸Lintels and beams over openings in light commercial projects.
▸Pergola and carport rafters across Western Sydney construction sites.
When to Choose SHS Steel
SHS distributes load evenly in all directions, making it a natural fit for vertical elements. It also offers a clean, symmetrical look suited to architectural and furniture applications.
Common uses include:
▸ Posts, columns, and uprights where loads come from above.
▸ Gate frames and fencing uprights across residential and rural properties.
▸ Furniture, handrails, and decorative steel elements.
▸ Structural columns in light commercial fabrication.
Where Sizes Overlap
There is some overlap in available sizes. A 50 x 50 SHS and a 75 x 50 RHS may be stocked in the same wall thicknesses and finishes, including painted and pre-galvanised options. For Sydney builders and Western Sydney fabricators, checking both columns before ordering is always worthwhile.
Ready to Order Rectangular Hollow Sections Serving Sydney?
Whether you need rectangular hollow sections for a structural frame or SHS for gate posts and columns, Waratah Steel Supplies stocks both in a range of sizes and finishes. Call 02 9608 9222 or get in touch through the contact page for a free quote. You can also browse the full range on the steel products page.
