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You search for “steel column timber beam connector” and half the results talk about HSS. The other half say SHS. The sizing looks different. The standards references are different. And you’re left wondering whether you’re looking at the same product or two completely different things.
You’re looking at the same product.
HSS and SHS are both square hollow steel sections used as structural columns. The only real difference is where you are in the world. This confusion trips up a surprising number of US builders — and it matters, because a lot of the best technical resources, connection systems, and cleat hardware on the market comes from Australia and the UK, where SHS is the standard term. If you’re only searching for HSS, you’re only seeing half the picture.
Here’s everything you need to know.
What HSS Means in the US
HSS stands for Hollow Structural Section. In North America, it’s the standard term for square, rectangular, and round hollow steel tubing used in structural applications. The American Institute of Steel Construction (AISC) uses HSS throughout its specifications, and US fabricators, steel distributors, and structural engineers all refer to square hollow posts as HSS.
US HSS sections are typically manufactured to ASTM A500 Grade B or the newer ASTM A1085 standard. Sizes are expressed in inches — a 4×4×¼ HSS is 4 inches wide, 4 inches deep, with a ¼ inch wall thickness. You’ll find these at most steel service centers and metal distributors across the country.
Common US applications include deck and porch support columns, pergola and carport posts, sub-floor bracing systems, light commercial framing, and verandah columns.
What SHS Means Everywhere Else
SHS stands for Square Hollow Section. It’s the standard term in Australia, the UK, New Zealand, and most of Europe. Same product — square hollow steel tubing used as a structural column — just specified under different national standards.
In Australia, SHS is manufactured to AS/NZS 1163. In the UK and Europe, it falls under EN 10210. Sizes are expressed in millimetres — a 100×100×4 SHS is 100mm wide, 100mm deep, with a 4mm wall.
Here’s where it clicks for most US builders: that 100×100mm SHS is essentially a 4×4″ HSS. The dimensions translate almost exactly. Which means that any cleat, connector, or bracket engineered for a specific SHS size will fit the equivalent US HSS post — no modification, no adapter, nothing extra required.
The Direct Size Conversion Table
Bookmark this. Every time you see an SHS product listed in millimetres, use this to find your US equivalent:
| US Size (HSS — inches) | International Size (SHS — mm) |
|---|---|
| 2½ × 2½” | 65 × 65mm |
| 3 × 3″ | 75 × 75mm |
| 3½ × 3½” | 89 × 89mm |
| 4 × 4″ | 100 × 100mm |
| 5 × 5″ | 125 × 125mm |
| 6 × 6″ | 150 × 150mm |
| 8 × 8″ | 200 × 200mm |
So when you see SHS Cleats listed for a “100×100mm SHS” post, you’re looking at a product that fits your 4×4″ HSS. A cleat listed for “150×150mm SHS” fits your 6×6″. The math is clean and consistent across the full size range.
Where They Actually Differ
Same product category, but a few practical differences worth knowing before you specify.
Manufacturing Standards and Wall Tolerance
ASTM A500 — the most common US standard — allows up to a 10% negative wall thickness tolerance. That means a ¼” (6.35mm) specified wall could legally be as thin as 5.7mm. For most residential applications this doesn’t matter. But for slide-on cleat systems where the cleat is precision-fitted to slide over the post’s outside dimension, tighter wall tolerances make for a cleaner, more consistent fit.
ASTM A1085, the newer US standard, tightens that tolerance to just 5% — closer to what AS/NZS 1163 and EN 10210 allow. If you’re using slide-on cleats and you want the best fit, specifying ASTM A1085 rather than A500 is worth the conversation with your steel supplier.
Yield Strength
ASTM A500 Grade B has a minimum yield strength of 46 ksi (317 MPa). ASTM A1085 pushes that to 50 ksi (345 MPa). AS/NZS 1163 Grade C350 sits at 350 MPa. These are close enough that for most residential connections, the difference doesn’t change the design. For engineered commercial connections, your structural engineer will specify the grade explicitly — follow their specification.
Availability
Standard US HSS in 4×4″, 6×6″, and 8×8″ is stocked by most steel service centers nationwide. Metric SHS in 100mm and 150mm increments is less commonly stocked domestically but is available through specialty steel suppliers. For most US jobs, you’ll source your posts locally as HSS and match them to the equivalent SHS cleat size using the conversion table above.
Which SHS Cleat Is Right for Your HSS Post?
Once you’ve got your post size sorted, choosing the right cleat is straightforward. It comes down to how the beam connects to the post and what type of beam it is.
SHS Timber Beam Cleats — for timber beams attaching to the side face of an HSS post. Verandah beams, roof beams, stairway landing bearers. This is the most common residential application.
SHS Top Plate Cleats — for timber floor bearers sitting on top of the HSS post rather than connecting to its face. Common in sub-floor framing and raised floor systems.
SHS PFC Beam Cleats — for steel Parallel Flange Channel (PFC) beams connecting to an HSS post. Used where loads are heavier and a steel beam is specified instead of timber.
SHS Bracing Rod Cleats — for connecting diagonal bracing rods to HSS posts. Sub-floor bracing, lateral bracing systems, communication towers.
SHS Baseplates — for anchoring the base of HSS posts to concrete footings, piers, or slabs.
All of these slide directly onto the HSS post on site, eliminating factory welding entirely. For installation details by post size and fastening method, see the SHS Cleats installation guide.
Frequently Asked Questions
Is HSS the same as SHS?
Yes. HSS is the North American term, SHS is used in Australia, the UK, and most of Europe. Both refer to the same product — square hollow steel tubing used structurally. The sizes convert directly: a 4×4″ HSS equals a 100×100mm SHS. A 6×6″ equals 150×150mm. The full conversion table is in this guide above.
What ASTM standard should I specify for HSS posts with slide-on cleats?
ASTM A1085 gives you tighter wall thickness tolerances than A500 — 5% vs 10% — which means more consistent outside dimensions and a cleaner fit with slide-on cleat systems. For most residential jobs, A500 Grade B works fine. But if you’re specifying on a project where dimensional precision matters, A1085 is the better call.
Where can I buy HSS steel posts in the US?
Most steel service centers and metal distributors stock standard HSS sizes (3×3″ through 8×8″) and can cut to length before delivery. Search for a structural steel supplier in your area — in most US cities and regional centers, you’ll find at least a couple of options within a reasonable drive.
Do SHS Cleats fit standard US HSS posts?
Yes. The full SHS Cleats range covers 2½×2½” (65mm) through 8×8″ (200mm) — the complete standard range for US residential and light commercial construction. Use the conversion table in this post to match your HSS post size to the right cleat, then check the product listings for configuration options.
Can I weld SHS Cleats to the post instead of using tek screws?
Yes. The system supports four fastening methods: tek screws only, structural bolts only, tek-and-stitch-weld, or full weld. Tek-only is sufficient for most residential applications and doesn’t require a welder on site. For heavier load applications or where your engineer specifies a higher connection capacity, the weld options give you more strength. See the installation guide for fastening specs by post size and load condition.
The Bottom Line
HSS and SHS are the same post. Once you know that, a much wider range of technical resources, products, and connection systems opens up — including slide-on cleat systems that are faster to install, easier to transport, and adjustable on site in ways that factory-welded assemblies simply aren’t.
If you’re working with HSS columns on your next deck, porch, or structural framing project, browse the full SHS Cleats range. Available in post sizes from 2½×2½” to 8×8″, with worldwide shipping.