Steel angle and angle iron are the same thing: an L-shaped section with two legs at 90 degrees. "Angle iron" is simply the old trade name, and the angle you buy today is steel, not iron. The distinction that actually matters is not the name but how the angle was made: hot-rolled structural angle from a steel mill, or cold-formed angle bent from thin sheet or plate. They look alike from a distance, behave differently under load and are designed to different standards.
This guide sorts out the names, explains how to tell hot-rolled and formed angle apart, and covers why the difference matters on a lintel, ledger or brace.
Why it's still called angle iron
Before steel was cheap enough to produce in volume, structural shapes were rolled from wrought iron. Steel took over through the late 1800s, and by around 1890 it had largely replaced iron for structural work. The names stuck. Tradespeople still say angle iron, channel iron and "iron work" for products that have been steel for well over a century.
You will see the same product described several ways:
| Name | Where you hear it |
|---|---|
| Angle iron | Trades, homeowners, hardware stores |
| Steel angle | Suppliers, fabricators, drawings |
| Angle bar | Suppliers and steel service centres, often for smaller angles |
| L-section or L-shape | Engineers, design handbooks |
| L102x102x9.5 (for example) | The designation on structural drawings |
On a Canadian structural drawing, angles are written with an L followed by the two leg lengths and the thickness in millimetres. Equal-leg and unequal-leg angles are both hot-rolled products; our post on equal vs unequal steel angle covers when each is used, and the steel angle sizes chart lists the common sizes with imperial equivalents.
What angle iron is made of today
Structural angle in Canada is low-carbon steel produced to a structural specification. The common grades are:
- CSA G40.21 300W or 350W, the Canadian structural grades.
- ASTM A36 or A572 Grade 50, the American grades that are widely stocked here.
Many mills certify one bar to more than one grade, so a single angle may carry a mill certificate showing both a CSA and an ASTM grade. The grade sets the guaranteed minimum yield strength and chemistry; the shape and size set the stiffness and capacity. For how the grade names work, see structural steel grades in Canada.
Angles are also made in other materials:
- Galvanized angle. Either a hot-rolled steel angle that has been hot-dip galvanized after cutting, or a light angle formed from pre-galvanized sheet. These are very different products that share a name.
- Stainless steel angle. Used where corrosion resistance or appearance matters, such as food plants or architectural trim.
- Aluminium angle. Light and corrosion resistant but much less stiff than steel. It is not a substitute for a steel angle on a structural detail.
Hot-rolled vs cold-formed angle
This is the real "steel angle vs angle iron" question for most buyers: is the piece in front of you a structural angle from a mill, or a formed angle made from sheet?
| Hot-rolled angle | Cold-formed angle | |
|---|---|---|
| How it is made | Hot steel passed through shaped rolls at the mill | Sheet or strip bent at room temperature on a roll former or press brake |
| Inside corner | Thickened root fillet | Inside bend radius, same thickness as the legs |
| Outside corner (heel) | Essentially square | Rounded |
| Thickness | Structural thicknesses, typically several millimetres and up | Usually thin, often ordered by gauge |
| Surface | Mill scale, often primed or galvanized after fabrication | Often pre-galvanized or pre-painted sheet |
| Design standard | CSA S16 | CSA S136 |
| Typical uses | Lintels, shelf angles, bracing, clip angles, frames | Steel stud framing, ceiling and wall trim, shelving, light brackets |
The 2024 Ontario Building Code sends the two products to different standards: Article 4.3.4.1 requires structural steel to conform to CSA S16, while Article 4.3.4.2 requires cold-formed steel members to conform to CSA S136. A formed angle can be a perfectly good structural member when it has been designed as one, but its capacity cannot be read from a hot-rolled angle table.
There is a third product between the two: bent plate, which is thicker plate formed on a press brake to any leg length or bend angle. It is common for pour stops, edge closures and odd-sized angles. Our guide to steel angle vs bent plate covers when a drawing calls for one instead of a rolled angle.
Is steel angle cold formed?
Standard structural angle is not. When a drawing shows an L-designation such as L76x76x6.4, it means a hot-rolled angle with published dimensions and section properties from the CISC Handbook of Steel Construction. A fabricator buys it by that designation, cuts it to length and drills, punches or welds it as detailed.
Cold-formed angle shows up in other places:
- Light steel framing, as track, clip angles and bridging made from galvanized sheet.
- Ceiling and drywall systems, as wall angles and trim.
- Slotted angle, the punched angle sold for shelving and racks.
- Retail "angle iron" at some hardware outlets, which can be either thin hot-rolled angle or a formed product depending on the brand and size.
None of these is wrong for its intended job. The problem comes when a light formed angle ends up doing a hot-rolled angle's job, such as carrying brick over a window.
How to tell which one you have
If the piece has no paperwork, a few quick checks usually settle it:
- Look at the inside corner. A hot-rolled angle has a visible fillet where the legs meet, so the corner is thicker than the legs. A formed angle has a smooth radius with the same thickness all the way around.
- Look at the outside corner. Hot-rolled angle has a sharp heel. Formed angle is rounded on the outside too.
- Check the leg ends. Rolled angles often have slightly rounded toes. Formed angles cut from sheet have square, sheared edges.
- Measure the thickness. Very thin legs, especially with a factory zinc coating on both faces, point to a formed sheet product.
- Look for markings and certificates. Structural steel arrives with heat numbers traceable to a mill certificate. If the job needs a certified grade and the steel has no paperwork, it cannot simply be assumed to meet it.
Why the difference matters on a job
Angles do a lot of structural work in houses and small buildings: brick lintels over windows and doors, ledger angles, shelf angles, bracing and connection clips. For these, three things have to be right.
- Size and orientation. Ontario's lintel tables list hot-rolled angle sizes, and an unequal angle has to be installed with the correct leg vertical. Our post on using angle iron as a lintel explains the code minimums.
- Grade and traceability. Engineered work assumes a known grade. Salvaged or unmarked steel is a guess.
- Corrosion protection. The code requires steel angle lintels supporting masonry to be prime painted or otherwise protected from corrosion. Exterior angles in wet walls are often galvanized.
Swapping a formed angle, a lighter angle or a different shape for what the drawing shows is a design change. On structural pieces, get the designer or engineer to approve it before anything is cut.
Ordering steel angle
Give the shop the designation (leg sizes and thickness), which leg is vertical if it is unequal, the grade if the drawings specify one, the length, any holes, slots or welded attachments, and the finish. We cut, punch, drill and weld angle lintels, ledgers and connection angles to your drawings in our CWB certified shop, and we can prime or galvanize to suit, with delivery across the GTA and Ontario.
Send your drawings or a cut list for a quote, or see the steel products we supply.
Frequently asked questions
Is angle iron the same as steel angle?
Yes. Angle iron is the traditional trade name for an L-shaped section, and today that section is rolled from steel, not iron. Steel angle, angle iron, angle bar and L-section all describe the same product.
What kind of steel is angle iron made from?
Structural angle sold in Canada is low-carbon steel made to a structural specification, usually CSA G40.21 300W or 350W, or ASTM A36 or A572 Grade 50. Many mills certify one bar to several grades at once. The mill certificate tells you which grade you have.
Is steel angle cold formed or hot rolled?
Structural steel angle is hot rolled: it is shaped by passing hot steel through rolls at the mill, which leaves a thickened fillet in the inside corner. Cold-formed angles also exist, bent from thin sheet or strip, but they are a light-gauge product designed to a different standard, CSA S136.
Can I use hardware store angle iron for a structural job?
Usually not without checking. Light slotted angle, thin galvanized angle and framing accessories are often cold formed from sheet and are not interchangeable with a hot-rolled structural angle. Lintels, ledgers and bracing should use the size and grade on the drawings or the code tables.
