A steel angle is a hot-rolled section with fixed leg sizes and a filleted inside corner; a bent plate is flat plate formed on a press brake to any leg length or angle you need. Specify rolled angle when a standard size does the job, and bent plate when the shape, bend angle or leg dimensions don't exist as a rolled section. Neither one can be swapped for the other on a structural member without the engineer of record agreeing to it.
This guide covers how the two differ in practice, where each one is the better fit, and what to put on the drawing so the shop builds what you meant.
How each one is made
Rolled angle comes from the mill. Steel is passed through shaped rolls until it forms an L. In Canada, angles are designated by leg lengths and thickness in millimetres, for example L102x102x9.5 (equal legs) or L127x89x7.9 (unequal legs). Every angle of a given designation has the same dimensions, mass and section properties, and those properties are published in the CISC Handbook of Steel Construction and the AISC shapes database. A designer can pick an angle off a table, and a fabricator only has to cut it to length, drill or punch it, and weld anything that attaches to it.
Bent plate starts as flat plate or sheet, cut to a strip of the right width and then bent cold on a press brake. Because it is made to order, the legs can be any length, the bend can be any angle, and a single piece can have several bends (a channel, a zed, a hat section). The section properties are not in any handbook; the designer has to calculate them for the specific shape and thickness.
The differences that matter on a drawing
| Rolled angle | Bent plate | |
|---|---|---|
| Inside corner | Fillet (root radius) set by the mill | Inside bend radius, which depends on thickness, grade and tooling |
| Outside corner (heel) | Essentially square | Rounded |
| Leg sizes | Only the rolled sizes | Any leg length the plate width allows |
| Bend angle | 90 degrees | Any angle, and more than one bend |
| Thickness | Only the thicknesses rolled for that leg size | Any plate thickness that can be formed |
| Lengths | Mill and stock lengths | Limited by press brake length and plate size |
| Design data | Published tables | Calculated for each shape |
| Toes | Slightly rounded toes on the legs | Square sheared or cut edges |
A few of these deserve a closer look.
The corner. The root fillet of a rolled angle is a deliberate thickening at the inside corner. It strengthens the section, but it also means a plate, a stiffener or another angle cannot sit tight into that corner: the mating piece needs a chamfer or clip to clear it. Bent plate has an inside radius instead, which on thicker plate is often larger than a rolled angle's fillet. Plate producers publish recommended minimum bend radii, and those minimums grow with thickness and strength. Bending too tight, or bending in the wrong direction relative to how the plate was rolled, risks cracking on the outside of the bend.
Springback and tolerance. Bent plate springs back a little after it leaves the press, so the shop over-bends to hit the angle. The result is accurate, but the tolerance on the bend angle and leg lengths is a shop tolerance rather than a mill tolerance. If the piece has to fit against something precise, say so on the drawing.
Length. Rolled angle is available in long mill lengths, and joining angles is rarely needed for ordinary lintels or bracing. A bent plate can only be as long as the press brake and the plate it is cut from, so a long run of bent plate may arrive in sections that are joined on site or in the shop.
When rolled angle is the better choice
Use rolled angle when one of the standard sizes does the job. That covers most:
- Masonry lintels. Ontario's Part 9 lintel tables are written around rolled angle sizes, and designers size lintels from those tables or from a CSA S16 check. Our steel angle lintel design example walks through one.
- Shelf angles and ledgers that carry brick or framing off a structure.
- Bracing, struts and frames where load tables and connection details are standard.
- Clip angles and connection angles at beam ends.
- Edge protection on curbs, slab edges and stair nosings where a rolled section in a common size is all that's needed.
Advantages here are real: published properties, consistent dimensions from piece to piece, long lengths, and no forming step. If a drawing calls for an angle and the size is a common one, there is rarely a reason to change it.
When bent plate is the better choice
Bent plate earns its place when the rolled section either doesn't exist or doesn't fit:
- Non-standard legs. A 150 mm by 40 mm leg combination, or a leg that has to match a specific slab or wall thickness.
- Bends other than 90 degrees. Sloped closures, flashings, and sills that follow a roof or wall line.
- Multiple bends in one piece. Pour stops (edge forms for concrete on metal deck), cover plates, channel or zed shapes in thicknesses no rolled section offers.
- Thin material. Rolled angles have a minimum thickness for each leg size; bent plate can go thinner where the design allows.
- Matching an adjacent plate. When a piece has to be the same grade and thickness as plate already on the job.
On structural work, a designer specifying bent plate takes on the job of checking that shape. That is normal for pour stops and closures, which are designed around the plate thickness and the slab edge. On a member that carries real load, like a lintel or a ledger, a rolled angle with published properties is usually the simpler design.
Steel angle without a radius
People sometimes ask for a "sharp corner angle" so that the inside corner is truly square. Neither product gives you that:
- A rolled angle always has the root fillet.
- A bent plate always has an inside radius, and a rounded outside corner too.
If the design truly needs a sharp inside corner, the options are:
- Weld two flat bars or plates into an L. This is a fabricated angle with a square corner (subject to the weld detail). It costs more than a rolled angle because of the fitting and welding, and the weld has to be designed if the piece is structural.
- Detail around the fillet. Chamfer or clip the corner of the mating part so it clears the root radius. This is the usual answer for stiffeners and gussets.
- Use a different shape. Sometimes a tee, a channel or a flat bar welded to the face of a member solves the problem without a sharp L at all.
Tell the shop why the corner matters (bearing, a seal, a clean architectural line) and the right option usually becomes obvious.
Substituting one for the other
Contractors and suppliers occasionally propose swapping an angle for a bent plate (or the reverse) because of availability or schedule. On structural pieces that's a design change: section properties differ, the corner behaves differently, and connections may need to change. Send the proposal to the engineer of record and get it approved in writing before anything is cut. On non-structural trim the architect makes the call.
Cost doesn't follow a simple rule either. A standard angle that only needs cutting is a simple item. A bent plate adds cutting and forming, but it can replace a welded built-up shape and save the fitting and welding. For how plate is bought and priced in general, see steel plate cut to size in Ontario and our guide to steel angle prices in Canada.
What to put on the drawing
Whichever you choose, give the shop enough to build it without guessing:
- Rolled angle: designation (for example L127x89x7.9), which leg is vertical, grade, length, holes or slots, and finish.
- Bent plate: thickness and grade, each leg dimension and whether it is an inside or outside dimension, the bend angle, any required inside radius, overall length, and the tolerance if the fit is tight.
- Either one: what it attaches to, so the shop can flag a clash with the fillet or radius before it becomes a site problem.
Getting angles and plate fabricated
We fabricate angle lintels and other angle pieces cut, punched or welded to your drawings, and cut and drill plate to your details, with CWB certified shop welding. If your drawings show bent plate, send them over and ask us how we would handle that detail for your job. Request a quote with your drawings, and see our services for fabrication, shop drawings and delivery across the GTA and Ontario.
Frequently asked questions
Is a bent plate as strong as a steel angle?
Not automatically. A bent plate and a rolled angle with the same legs and thickness have slightly different section properties because of the corner shape, and the bent plate's capacity has to be calculated rather than read from a handbook. The engineer of record decides whether one can replace the other.
Can you get a steel angle without a radius?
Not as a hot-rolled section. Rolled angles always have a fillet at the inside corner, and bent plate has a radius on both faces. A sharp inside corner means welding two flat pieces together, or detailing the mating part to clear the fillet.
Why would a drawing call for bent plate instead of angle?
Usually because the shape is not available as a rolled angle: unusual leg lengths, a bend other than 90 degrees, more than one bend, or a thickness that does not match the rolled sizes. Pour stops and edge closures are common examples.
Which is cheaper, angle or bent plate?
For standard sizes in ordinary lengths, rolled angle is usually the simpler item because it only needs cutting. Bent plate adds a cutting and forming step, but it can save welding or replace a shape that would otherwise need to be built up. The quote depends on the size, length and quantity.
