What Is Cold Formed Steel Metal Framing?

29 Apr.,2024

 

What Is Cold Formed Steel Metal Framing?

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?

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 reheated. 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.

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.

6 Main Types of Cold-Formed Steel Sections

1. Studs

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 or column/post. Deeper stud sections can be used for floor joists, roof joists, and beams.

2. Track

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.

3. U-channel

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.

5. L-header

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.

6. Straps

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.

Benefits of Cold-Formed Steel Framing in Structural Applications

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 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 wood stud weighs about 14 pounds and the metal stud weighs 20 pounds. Cold-formed steel has a strength-to-weight ratio of 400, whereas the wood stud strength-to-weight ratio is 178.
  • Cost: Many single-story and mid-size multi-story buildings can be constructed entirely out of cold-formed steel, which eliminates the need for hot-rolled structural steel. This can translate into cost savings in terms of fewer materials and shorter construction times by eliminating cranes for steel erection. Additionally, there is no special forming of concrete piers for columns, less laydown area, and less trades.
  • Ease of Use: Cold-formed steel framing is a very light material to work with. Once it’s dropped off in pallets on the site, the only equipment used to install it are readily accessible equipment like forklifts, manlifts, saws, and drills. No cranes or special formwork is required.
  • 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.

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
  • Bits
  • Bit holders for structural steel to steel connection
  • Hand seamer for positioning and bending steel
  • Chop saw
  • Pneumatic/Powder Actuated pin-nailer
  • Clamps
  • 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.
  • Transportation/storage costs: Cold-formed steel takes up a small footprint on a jobsite. It is often delivered for day-of installation and is usually transported on a single flatbed. This means there is no crane rental, no crane space, little storage space, and far fewer deliveries. This smaller impact to the construction site also improves overall jobsite safety.

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 that, 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 might be stronger for one manufacturer than another, and some manufacturers may have better quality assurance/quality control processes than others.

The specifier should consider the project’s location and use when specifying the stud galvanizing thickness. While G60 is common for exterior stud walls, structures in a high moisture environment (pools) or near a high salt area (ocean) might consider a thicker coating, such as G90. Even thicker coatings are possible, but you may be required to purchase a whole coil of steel.

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 engineer during the bidding phase to get preliminary sizes and/or an understanding of costly details.

Cold-Formed Steel Design Submittal Best Practices

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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:

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.

What Is Cold-Formed Steel Framing and How Can I Use It?

Because Cold-formed steel (CFS) framing is light weight, extremely strong, noncombustible, and relatively easy to install, it has dominated the market for interior, non-loadbearing partition walls in commercial construction.  Now, with advanced technological developments like panelized systems, the building community is using CFS for structural applications in mid-rise and multi-housing buildings.

In fact, cold-formed steel framing is rapidly becoming the material of choice for student dormitories, assisted living facilities, and hotels across the country where prudent developers are interested in maximizing their return on investment.

What is cold-formed steel?

Cold-formed steel (CFS) members are made from structural quality sheet steel that are formed into C-sections and other shapes by roll forming the steel through a series of dies. No heat is required to form the shapes (unlike hot-rolled steel), hence the name cold-formed steel. A variety of steel thicknesses are available to meet a wide range of structural and non-structural applications.

Value-benefit of steel

CFS as a construction material has many advantages. For example, CFS doesn’t shrink or split, won’t absorb moisture, and resists warping, termites, and fire.

As a uniformly manufactured product, the quality of CFS is very consistent. That consistency translates into less scrap to haul off because there is less waste — all of it recyclable. In addition to lowering scrap disposal expense, the fire resistance of CFS framing also can help reduce project costs through discounts on builders’ risk and other course of construction insurance requirements.

CFS’ physical properties allow it to be used in a wide range of environments. It’s strength and ductility, for example, make it ideal for construction in regions subject to high winds or earthquakes. Moreover, a study, conducted by the National Association of Home Builders (NAHB) Research Center, showed that the zinc coating on steel framing materials can protect against corrosion for hundreds of years.

And because each piece of CFS contains a minimum of 25 percent recycled content, is 100 percent recyclable at the end of its lifespan, and emits no volatile organic compounds — it’s an exceptionally sustainable building material.

On the jobsite

CFS also provides numerous advantages in terms of the construction process itself. CFS is light making it easy to ship, handle and assemble.

Moreover, greater strength means less material. For example, if a project calls for stick framing, the strength of CFS allows it to be installed on 24” centers rather than traditional 16” centers — meaning fewer studs to install.

And because CFS is manufactured to exacting standards, it is ideally suited for manufacturing into panels and trusses which — because CFS is light in weight — can be quickly and easily installed with fewer framers on the job.

Given those advantages, some builders have found that ordering factory-manufactured steel panels and trusses is an ideal way to move into steel framing because it minimizes the need for skilled framers, and provides access to experienced design and layout pros.

In addition to speeding up the framing process, CFS panels contain pre-punched holes designed to accommodate rapid mechanical, electric and plumbing installation after the framing is complete.

Training

It is not difficult to train a crew to work with CFS. Experienced framers find it relatively easy to learn to frame with steel. Aside from applying their existing skills to a new set of framing components — for example, steel C section studs instead of wood studs; formed steel single tracks instead of top and bottom wood plates; and hex-, pan- and bugle-head screws for framing in addition to pins (nails for steel connections) — framers only need to spend a bit of time mastering the use of a small number of new tools and fasteners.

The list of basic CFS framing tools is rather short. A typical toolset might include an adjustable-torque screw gun, bits and bit holders for structural steel-to-steel connections, a hand seamer for positioning and bending steel, a chop saw, a pneumatic pin-nailer for steel-to-steel connections and sheathing-to-steel connections, clamps, aviation snips, a swivel-head electric shear, and a magnetic level.

Wide acceptance

With the adoption of the American Iron and Steel Institute’s North American Standards for Cold-Formed Steel Framing into the International Code Council’s International Building Codes, builders and designers can find comprehensive provisions for steel.  These standards are also available as a free download from the American Iron and Steel Institute.

Want more information about getting started with cold-formed steel framing? Download “A Builder’s Guide to Steel Frame Construction.”

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