Cold-formed steel framing has become a popular choice in construction projects, with contractors now more often choosing cold-formed steel over traditional wood framing.
But what exactly are the common types, the benefits, and what should you consider when ordering from a manufacturer? In this comprehensive guide, we’ll explore everything you need to know so you can order the right materials. We’ve also included a helpful list of resources and technical guides that you can reference when embarking on your next cold-formed steel framing project.
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- What Is Cold-Formed Steel and How Is It Used?
- Benefits of Cold-Formed Steel Framing
- Overview of Cold-Formed Steel Sections
- Types of Cold-Formed Steel Sections
- Training Framers New to Cold-Formed Steel
- How Cold-Formed Steel Can Reduce Construction Costs
- What Contractors Need to Know When It Comes to Shop Drawings
- Considerations When Ordering Cold-Formed Steel from Manufacturers
- Cold-Formed Steel Design Submittal Best Practices
- Technical Guides & Resources
What Is Cold-Formed Steel and How Is It Used?
Cold-formed steel (CFS) refers to thin steel that has been rolled to less than 1/8th of an inch and bent into a specific shape without being reheating. It’s often found in appliances, cars, and laptops. Cold-formed steel framing, however, is used in construction where thin sheets of steel are typically formed into shapes to take advantage of its large strength to weight ratio. The most commons shapes are C, Z, U, or hat channels
Benefits of Cold-Formed Steel Framing
There are many reasons why you should consider CFS framing if you’re constructing a building, including:
- Strength-to-weight ratio: This is one of the biggest advantages. Cold-formed is steel is relatively lightweight compared to its strength. For example, an 8-foot tall 2×4 stud has a capacity of approximately 2,500 pounds. An 8-foot long 3-5/8-in 12 gauge metal stud can hold 8,000 lbs. The equivalent wood stud weighs about 14 pounds and the metal stud weighs 20 pounds. Cold-formed steel has a strength-to-weight ratio of 400, where the wood stud is 178.
- Non-combustible: CFS will not ignite or burn, which helps with a building’s fire rating and safety. Non-residential structures are often required to be built of non-combustible materials.
- The ability to construct taller residential buildings: CFS allows you to build 12- or 13-story load bearing buildings, as compared with wood, which is usually limited to 4 or 5 stories of load bearing.
- No twisting or shrinkage: CFS is ideal because it holds its shape and length. It does not warp or twist like wood.
- No rotting. Since CFS is not a food source, you do not have to worry about rotting or issues with insects and termites. Plus, CFS is galvanized, which protects against corrosion.
Overview of Cold-Formed Steel Sections
Cold-formed steel is a unique building material. With most materials (wood, steel, concrete, etc.), the designer determines the elastic or plastic limit of the material and backs off from that limit by some factor of safety. Cold-formed steel is limited by buckling before it experiences elastic or plastic limits. Buckling controls most of the design aspects.
- Stiffened vs. unstiffened elements — The buckling capacity of a plate element can be increased by stiffening portions of the plate. This is often achieved by bending a corner or ridge in a plate member. As an example, the flange of a stud is stiffened by the lip return. The flange of a track is unstiffened on the free edge. Understanding the improvement in strength due to stiffened members is key in CFS design.
- Local buckling — This buckling of material, particularly the web or flange elements of a stud is called “local buckling.” Designers still need to be concerned about “global buckling” of compression elements. However, many non-compression dominant members will often have local buckling issues to consider. For example, the bearing of a joist on a wall. The web of the joist is subject to local buckling and need to be checked.
Types of Cold-Formed Steel Sections
A stud refers to cold-formed steel that has been formed into a C-shape with a lip return. These are typically used as a vertical element in the framing of a wall.
A track section will often cap the bottom and top of a steel stud wall. These products are U-shaped and do not have a lip return to allow the stud to seat inside the track.
This is a smaller U-shaped product that goes through the web knockout of each stud for bracing or will often be used to support ceiling framing with hanger wire. It’s important to note: standard studs have knockouts that are oval shaped holes at a periodic spacing used for electrical conduit or plumbing; a U-channel can pass through these knockouts and tie studs together for bracing.
4. Furring channel
This refers to a “hat-channel” type of CFS that is often applied to the face of wall or bottom of ceiling in order to provide a wedge or spacing element (otherwise known as furring) to the sheathing. This can help reduce sound transmission or improve fire resistance.
This piece of CFS is a large angle, or L-shaped, and is positioned on top of the wall top track to act as a simple header. They span across openings to help transfer the load over a door or window onto jamb studs. L-headers are less common in construction.
Straps are 2 to 12-wide thin sheets of steel used for tension loads. They will most often be found in wall bracing or shear walls.
Training Framers New to Cold-Formed Steel
Training for CFS is very similar to wood construction. Framers can apply existing skills with new CFS framing tools, which include:
- Adjustable torque screw gun
- Bit holders for structural steel to steel connection
- Hand seamer for positioning and bending steel
- Chop saw
- Pneumatic/Powder Actuated pin-nailer
- Aviation snips
- Swivel-head electric shear
- Magnetic level
How Cold-Formed Steel Can Reduce Construction Costs
Another reason to consider using cold-formed steel is the potential for considerable cost savings. Like wood framing, the material costs for cold-formed steel are per unit (pound or board foot), but 70% of the cost in construction is the labor. The high strength-to-weight of steel allows for fewer members to be used in assemblies. For example, we often use one stud jambs vs. a king and a jack stud for wood.
Here are a few ways cold-formed steel can reduce construction costs:
- Consider using ClarkDietrich’s Heavy Duty Stud (HDS) framing: Using heavier gauge steel and large member sizes at headers, jambs, and sills can reduce or even eliminate the time it takes to assemble a built-up, multi-piece section. HDS has slightly less steel weight and will probably cost slightly more because it’s a specialty product. But what you save in construction time will likely offset the special order costs.
- Eliminate unnecessary wall bracing: Bracing is used to reduce the length of the unbraced compression flange of a stud. Plywood and gypsum can provide this bracing in most circumstances. Calculations in submittals can identify this and unnecessary wall bracing can often be removed.
- Pre-cut studs: There is no extra cost for pre-cut studs more than 6 feet long. Let the factory know where the studs will be installed, and they will label the bundles. But make sure you get your lengths correct. Pre-cut studs typically can’t be returned.
If you’re looking for more detailed examples, check out: 9 Ways Cold-Formed Steel Contractors Can Reduce Costs.
What Contractors Need to Know When It Comes to Shop Drawings
The owner of a building (new or under renovation) will typically hire a design team, including an architect and structural engineer, to produce construction drawings that describe the intent of the project. As an example, the structural engineer will likely size columns and beams, but is often not as concerned with the methodology of how those beams will be connected if the connection meets the design loads. In some cases, the beams could be welded; in others, they could be bolted together.
Construction drawings speak to the intent of the building and do not necessarily dictate specificity of means and methods, whereas shop drawings are more product-specific and describe how the structure will be built and how it meets the required design parameters. (For example, construction drawings might size a joist as a 1000S200-68 at 16” o/c and give the loads, but the number of screws and connectors would be specified in the shop drawing.)
It is important to keep in mind that building codes require that cold-formed steel framing, whether interior or exterior, to be designed by a design professional (a licensed architect or engineer.) In some cases, the structural engineer or architect who produced the construction drawings may choose to take responsibility for the CFS framing and may not require shop drawings — but this is rare.
In most cases, the structural engineer — otherwise known as the engineer of record — provides performance specifications, such as the ability to handle a specified wind load. The structural engineer will then rely on a specialty structural engineer, such as a cold-formed steel engineer, to design the framing elements and produce a set of shop drawings. The specialty engineer is often hired by the subcontractor responsible for the cold-formed steel framing.
In any construction project, it’s essential to review architectural specifications, ask for clarification if needed, and know who is responsible for which components of the job. It is too late to find out that you need shop drawings when you begin to mobilize for a job.
Considerations When Ordering Cold-Formed Steel from Manufacturers
There are certain industry standards when it comes to the manufacturing of cold-formed steel stud and joist framing. This means, for the most part, you will find similar products among manufacturers.
There are, however, some pitfalls to be aware of. Not all manufacturers use the same grade of steel for their studs. For example, 16 gauge material for one manufacturer might be stronger than another, and some manufacturers may have a better quality assurance/quality control processes than others.
When it comes to angles and clips, premanufactured connectors by Clark Dietrich, Simpson StrongTie, and The Steel Network are the most common in the industry. However, they are all proprietary and have different capacities and uses. Equivalency charts should be used with caution.
It’s also important to remember that unlike wood framing, you can order CFS studs to specific lengths. Precut studs can save a lot of time on a project, but they require careful planning.
Many projects are bid and won prior to the involvement of a specialty engineer. Bidders can avoid costly mistakes by working with a specialty engineering during the bidding phase to get preliminary sizes and/or an understanding of expensive details.
Cold-Formed Steel Design Submittal Best Practices
In this section, learn more about what contractors should consider when submitting cold-formed steel design drawings and how to identify potential costly details.
- Stud size: Pay attention to stud heights as a small difference in height, such as 3-feet, can change the required gauge to increase two increments. Strict deflection limitations can also drive costs. Consider the geographic area (in terms of high wind speeds near the coast) If you aren’t sure which sizes you need, it’s best to consult a cold-formed steel engineer.
- Wall bridging: Is bridging even necessary? If you’re designing a load-bearing building, it’s required 99% of the time. But with non-loading bearing walls, most projects don’t need wall bridging and gypsum sheathing may be used instead, which will save you time and money. (Note: walls without sheathing will require bridging.)
- Storefront door/windows: Be aware that when you have a door inside of a window system with an elevated sill you’ll have to coordinate this potentially expensive detail ahead of time. It may require cantilevering the studs off the foundation wall or going back to the design team to have steel embedded into the foundation.
- Parapets: Unless the parapet is framed with bypass studs, under 2 feet in height, or have kickers, these can be expensive details to correct. Check with your structural engineer, and ask for a spot check. If you have tall, cantilevered parapets off the roof deck, request more information from the project engineer and ask how the parapet is expected to stay up. You may need to request kickers or structural steel posts. It’s also important to tackle this challenge as early as possible.
- Blast loads: Projects with blast loads (a requirement for federal projects), are much more expensive. Connections are much heavier, and sometimes you may need them to be customized. If you’re bidding on a federal project, know that blast loads could be an issue you need to deal with, and you must budget accordingly. Look for any terminology referencing “blast loads” or “Anti-Terrorism Force Protection (ATFP).” It’s also recommended that you reach out to a cold-formed steel engineering firm that has experience in designing with blast loads. They can provide more information about the stud sizes and connections you may need.
Technical Guides & Resources
Are you looking for codes, standards, and more industry information? We’ve compiled a list of cold-formed steel framing technical guides and resources, which include:
- The American Iron and Steel Institute (AISI)
- The Cold-Formed Steel Engineers Institute (CFSEI)
- The Steel Framing Industry Association (SFIA)
- ClarkDietrich Building Systems Structural Stud Lookup
- ClarkDietrich Building Systems Structural Studs
- Product Technical Guide from the Steel Stud Manufacturers Association
If you have questions about cold-formed steel services, or you’re looking for a quote for your next project, please contact us today. We look forward to answering your questions and learning about your next project.