Steel angle is a structural steel section with two flat legs joined at a right angle, so its end view is an "L". It's the same product people call angle iron or angle bar, and today it's rolled from steel to a structural grade. In construction, angle does a lot of small but important jobs: lintels over openings, shelf angles that carry brick, clip angles that connect beams, bracing, ledgers and frames around openings.
This guide explains what a steel angle is, how its size is written, and the main places it's used on houses and commercial buildings. For the history of the "angle iron" name and the difference between rolled and formed angle, see steel angle vs angle iron.
What steel angle is
An angle has just two parts: two legs meeting at a heel (the outside corner). The free edges are called toes. On a hot-rolled angle, the inside of the corner has a rolled fillet that makes it slightly thicker than the legs, and the heel is sharp.
Angles come in two families:
- Equal-leg angles, where both legs are the same length, such as L76x76x6.4.
- Unequal-leg angles, where one leg is longer, such as L127x89x7.9. The long leg is usually set vertical when the angle carries load as a lintel or ledger, because that's how it's stiffest.
On Canadian drawings, an angle is written as L, then the two leg lengths, then the thickness, all in millimetres. Imperial drawings use inches (L3x3x1/4 is the US name for L76x76x6.4). The steel angle sizes chart lists the common sizes with their kg/m.
Structural angle in Canada is usually supplied to CSA G40.21 300W or 350W or ASTM A36 or A572 Grade 50, often certified to more than one at once. The grade sets strength; the size sets stiffness.
How an angle behaves under load
An angle is light, cheap to fabricate and easy to connect, but it's not an efficient beam or long column. A few properties explain why:
- It's not symmetrical about a vertical axis. An unequal angle, and an equal angle loaded on one leg, doesn't bend straight down under a vertical load. Its principal axes are inclined, so it sags and twists slightly sideways unless it's restrained.
- It buckles about its weakest axis. In compression, an angle tends to buckle about a diagonal axis through the heel, which has the smallest radius of gyration (rz in section tables). That's why single angles make short struts and braces rather than tall columns.
- It's often loaded eccentrically. A clip angle bolted by one leg, or a lintel carrying brick on its horizontal leg, takes load off-centre. Designers account for that.
None of this is a weakness for the jobs angles normally do. It's the reason the size and orientation on the drawings matter. Our post on steel angle load capacity shows how angle capacity is worked out.
Where steel angle is used in houses
Angle is the most common piece of structural steel in many houses:
- Lintels over windows and doors in brick or block walls. A steel angle sits in the masonry and carries the brick above the opening. Ontario's Building Code has its own lintel tables and requires at least 150 mm of bearing at each end; it also requires steel lintels supporting masonry to be prime painted or otherwise protected against corrosion. See using angle iron as a lintel for the code details.
- Garage door and wide opening headers in brick veneer. Longer openings often use a heavier angle, two angles, or an angle bolted to a beam or channel.
- Ledger angles. An angle bolted to a foundation wall or a steel beam gives joists or a wood ledger something to bear on.
- Post and beam connections. Small angles act as clips to tie wood or steel members together.
- Basement egress and window openings. New openings cut in foundation walls often need an angle or other steel lintel, designed to suit.
Where steel angle is used in commercial buildings
In larger buildings, angle shows up all over the frame and envelope:
- Shelf angles (relieving angles). Angles fixed to the frame or slab edge at intervals up the building carry each band of brick veneer, so the full height of brick doesn't stack on the foundation.
- Clip and connection angles. Pairs of angles bolted or welded to a beam web are a classic simple shear connection to a column or girder. Seated connections use an angle under the beam. See clip angles and ledger angles.
- Bracing. Single and double angles serve as diagonal braces, struts and sway bracing, especially in lighter frames and towers.
- Joist and truss members. Open web steel joists commonly use angles for their chords and web members.
- Opening frames and deck support. Angles frame roof openings for hatches, rooftop units and ducts, and support steel deck where it meets walls and openings.
- Embedded edge angles. Angles with welded anchors are cast into slab edges, loading dock edges and stair landings to protect the concrete and give something to weld to later.
- Miscellaneous supports. Light fixture supports, pipe supports, door frame stiffeners, ladder rails and equipment stands are often built from angle.
Angle vs other shapes for the same job
Angle isn't always the right answer. Here's how it compares for common tasks:
| Job | Angle works when | Consider instead |
|---|---|---|
| Masonry lintel | Short to moderate openings, brick veneer | Angle plus beam or channel for long or heavily loaded openings |
| Ledger | Light joist loads | Channel or bolted wood ledger on a steel beam |
| Brace | Short braces, tension bracing | HSS for long compression braces |
| Frame or curb | Light openings and supports | Channel where a flat back and deeper section help |
| Beam | Rarely | W-beam or HSS |
When a drawing calls for a particular angle size, swapping it for a lighter angle, a formed angle or a different shape is a design change that the designer should approve.
Practical points when buying steel angle
- Rolled, not formed, for structural work. Thin formed angle from a hardware aisle or a framing system isn't a substitute for a hot-rolled structural angle on a lintel, ledger or brace.
- Orientation. For unequal angles, say which leg is vertical. For lintels, the horizontal leg needs to be wide enough to carry the masonry.
- Finish. Exterior and in-wall angles are usually primed or galvanized. Galvanizing is common for shelf angles and lintels in brick walls.
- Holes and slots. Bolted angles need holes punched or drilled at the right gauge lines. Slotted holes are often used on shelf angles to allow adjustment.
- Bearing and length. Lintels need full bearing at each end, so order them long enough for the opening plus bearing.
Structural uses of angle (lintels, ledgers, connections and bracing) are part of the building's structure. In Ontario, new or enlarged openings and other structural changes need a designer or engineer and usually a building permit.
Steel angle fabricated to your drawings
We cut, punch, drill and weld angle lintels, ledger angles, clip angles and frames to your shop drawings in our CWB certified shop, and we can prime or galvanize to suit, with delivery across the GTA and Ontario. For miscellaneous pieces, we fabricate and deliver, and installation is by your installer or contractor.
Send your drawings or a cut list for a quote, or see the steel products we supply, including angle lintels.
Frequently asked questions
What is steel angle used for?
In construction, steel angle is used for lintels over masonry openings, shelf angles that carry brick veneer, clip angles that connect beams, ledger angles, bracing, frames around roof and floor openings, embedded edge angles in concrete, and supports for equipment and light fixtures.
What is a steel angle bar?
Angle bar is another name for steel angle, an L-shaped section with two legs at 90 degrees. Suppliers sometimes use the term for smaller angles. It is the same product as angle iron and steel angle, written L followed by the two leg lengths and the thickness, such as L76x76x6.4.
What is rolled steel angle?
Rolled steel angle is angle shaped at a steel mill by passing hot steel through grooved rolls. It has a square outside corner, a thickened fillet inside the corner and published section properties, and it is the angle meant on structural drawings. Formed angle bent from sheet is a lighter, different product.
Why is it called angle iron if it's steel?
Structural shapes were rolled from wrought iron before steel took over in the late 1800s, and the trade name stuck. Angle iron sold today is steel, normally made to a structural grade such as CSA G40.21 300W or 350W or ASTM A36.
