SHS on a drawing means Square Hollow Section — square steel tube, sized as outside face by outside face by wall thickness, as in 100x100x5.0 SHS.
SHS stands for Square Hollow Section: square steel tube used structurally. Posts, portal legs, bracing, lintels, handrails, verandah and carport framing — anywhere you want a closed section that is equally stiff both ways and tidy to look at.
In AU and NZ the product standard is AS/NZS 1163, cold-formed structural steel hollow sections, designed to AS 4100. Three members of the same family:
- SHS — square
- RHS — rectangular
- CHS — circular, i.e. round tube
How SHS appears on a drawing
The designation is outside dimension x outside dimension x wall thickness. A post callout:
P2: 89x89x3.5 SHS GR C350L0, 200x200x10 BASE PLATE, 4/M12 CHEM ANCHORS
Read: post mark P2 is 89 mm square tube with a 3.5 mm wall, grade C350 with guaranteed impact properties at 0 °C, on a 200 mm square 10 mm thick base plate fixed with four M12 chemical anchors.
The order of those numbers is the whole game. 89×89 is the outside of the tube, not the opening. The inside measures 89 less two wall thicknesses, about 82 mm across the flats, and less again at the corners where the internal radius runs. That is what catches anyone trying to sleeve one section inside another.
Other forms you will meet: SHS 100x100x6.0 with the letters first, or 100 SQ HOLLOW SECTION x 5 WALL spelled out on older sheets.
Grades under AS/NZS 1163 are C250, C350 and C450, each with an L0 subgrade for guaranteed low-temperature impact properties. C350L0 is the everyday structural grade. Galvanised and in-line galvanised product is common here, and the finish is called up separately.
One local quirk: 89×89 is 3½ inches in metric clothing (88.9 mm), and 75×75 sits beside the old 3 inch. Both are real, stocked sizes — do not silently round 89 up to 90, because 90×90 is not in the structural range. 65×65, by contrast, is just a metric size.
Terms it gets confused with
- RHS — rectangular. Plenty of offices say “RHS” loosely for the whole family, so a note reading
100x100 RHSis almost certainly a square section. Trust the dimensions over the letters. - HSS — the US name for the same family of products.
- Tube versus pipe — a square or rectangular section is named by its actual outside dimensions, so a 100×100 SHS really is 100 mm across the flats. Round sections are where it bites: CHS is designated by outside diameter (
Ø114.3 x 4.5 CHS) but is ordered by nominal bore, and 100NB CHS is 114.3 mm OD — the same outside diameter as DN100 pipe, and nothing like 100 mm. - Cold-formed versus hot-finished — AS/NZS 1163 is cold-formed. Hot-finished square tube exists (to EN 10210 in Europe) with larger corner radii and different properties. Not an automatic substitution.
- “Steel hollow section” — heard on site as SHS too, meaning the family generally rather than the square one. Check the dimensions.
AU/NZ versus UK/Europe versus US
- AU and NZ — SHS to AS/NZS 1163, cold-formed, grades C250/C350/C450 with L0 variants:
150x150x9.0 SHS C350L0 - UK and Europe — also called SHS. Cold-formed to EN 10219, hot-finished to EN 10210, with S235/S275/S355 grades and suffixes:
150x150x10 SHS S355J2H - US — HSS, hollow structural section, to ASTM A500 or the tighter-tolerance A1085, named in inches:
HSS6x6x1/2is 6 in square with a 1/2 in wall. A US fabricator may not recognise “SHS”, and older US drawings use TS for tube steel. A500 also permits wall under-tolerance, with AISC design values based on a reduced design thickness — the AU assumption does not carry across.
Where to check on your own set
- The column or post schedule and the steel general notes, for grade, finish and product standard.
- The abbreviation legend on the first structural sheet.
- The specification, for galvanising, sealing and capping. A hollow section that fills with water is a durability problem.
- Supplier section tables, for the sizes actually made, corner radii and real internal clearance, before you detail a sleeve or a bolt straight through.
- If the callout says HSS with imperial numbers, you are on a US-convention set and should use their tables.
SHS, RHS, CHS and the rest of the section shorthand are listed in the A-Z of engineering drawing abbreviations.
Other meanings of SHS
Outside drafting, SHS most often means Senior High School, and in development and energy work Solar Home System. There is no strong competing meaning inside construction drawings — the real risk is the loose use of SHS for “steel hollow section” generally, covered above.