Steel channel is a versatile product that is available in many sizes and thicknesses. Its cross-section is shaped like a squared-off C, with a straight back and two perpendicular extensions on the top and bottom. Some types of steel channel (C Purlin) add short inward-facing lips to the end of the extensions, parallel to the back, which makes the structure more rigid, similar to rectangular steel tubing. Other types of channel (Unistrut) have holes or perforations for bolting purposes, and others may add a slight ridge to the back to further increase rigidity.
Compared to other structural steel products, such as I-beams, steel channel is lighter and slightly more flexible, though it offers less torsional strength, making it prone to twisting under certain conditions. It offers improved rigidity over flat steel stock, and is slightly stronger when used lengthwise than the equivalent thickness of angle iron.
Steel channel has many uses, mostly structural, and here are a few common examples:
Steel channel is often used to build walls for things like garages, warehouses, workshops, and other metal buildings, where they are used like studs in conventional wood framing. The studs run vertically from the bottom plate of the wall to the top plate, and the bear the vertical load of the building. Compared to a wood stud, steel channel can support a much greater amount of weight and it is much more rigid, while the weight difference between wood studs and the steel channel is negligible. Of course, the steel channel is more difficult to install, as it requires welding, bolting or riveting, rather than simply driving nails.
Steel channel can be used in pole barns to form the walls, where it is run horizontally from pole to pole to provide an attachment point for the siding on the exterior, which is often sheet metal. It can also be run along the interior to provide support for drywall or other interior wall finishes. By using steel channel instead of wood slats or other products, the distance between the poles can be increased without compromising the integrity of the wall. Over longer lengths, wood can easily warp or twist, making the finished wall appear wavy or uneven, and reducing its rigidity and load-bearing ability.
On light-duty roofs, steel channel can be used as rafters, running from the eaves of the roof to the ridge, where they provide support for the roof deck. By using steel channel instead of wood rafters, the rafters can be smaller and lighter, while still supporting the same amount of weight. Compared to wood, the steel channel is stronger and longer-lasting, and it will not be damaged by rot, fungal decay or moisture, On heavy-duty roofs, I-beams are often used as the rafters and the ridge, and steel channel is placed perpendicularly on top of the rafters every few feet, from the ridge down to the eave. This allows the steel channel to bridge the gaps between the rafters, allowing them to be further apart, and provides an attachment point for the steel deck.
Steel channel can be used to create secure frames for windows and doors in both metal and wood-framed buildings. Four pieces are cut with miter joints on each end, and the channel slides over the wall in the window or door opening. This leaves a flat surface in the opening to mount a door or window to, and it is much more secure than frames made from wood. Steel channel is often used to create the frames for commercial fire doors, as well as sub-grade basement doors.
When extra strength is needed in a wood-framed building, steel channel can be used to increase the rigidity and strength of wooden beams. Wood beams can be placed inside a large steel channel, providing extra strength, while still allowing easy attachment of joists and other components to the wood beam. Alternatively, smaller steel channel can be placed at the bottom of the beam, and supported by posts, to increase the strength of an existing beam during a remodel. It could also be placed on top of the beam as a cap, to provide extra strength during the construction of a home.
Steel channel is often used to construct the frames of vehicles, and is often specially-formed for that particular function. Heavy-duty steel channel is typically used to create the main frame rails, running from the front of the vehicle to the back. Lighter steel channel can also be used to create cross members, braces or for structural components such as radiator supports. When used in a vehicle, steel channel provides enough strength and rigidity to prevent the vehicle from flexing too much, while still allowing a bit of movement to compensate for the torque produced by the engine.
Steel channel is often used for the construction of trailers, including flatbed trailers, box trailers, and even travel trailers and RVs. Heavy-duty steel channel can be used to create the main frame rails and the tongue, where it attaches to the towing vehicle. It can also be used as joists running perpendicularly to the frame rails to build the structure of the floor, as well as for the outer edges of the trailer. Flooring, made from wood or metal, would then be attached to the joists to finish the deck of the trailer. Steel channel can also be used to create rails to secure the load, or as studs to create the walls and roof of an enclosed trailer, such as a box trailer or a travel trailer.
Steel channel is often used in conjunction with I-beams and other steel products to build commercial and industrial buildings, such as warehouses. It can act as girts, studs, braces, joists or other structural components where the added strength of an I-beam is not necessary. It is often welded, bolted or riveted into place, and provides plenty of strength and rigidity for its weight.
Steel channel can be used for many other structures as well, such as railings, stair stringers, bridge trusses or guard rails. It is a versatile product that is strong, light, and relatively maintenance-free.