Cold-Formed Steel Framing has been around in commercial construction since the 1960s.
The short answer is everything. Cold-formed metal framing is an excellent option for areas where you are concerned about life safety because of inherent non-combustible properties and termite and pest resistance close to ground level. Areas where dimensional stability are important such as mid-rise and multi-story structures or multiple building structures (poured-in-place concrete, masonry, etc.) is being used. CFS has excellent long-term durability and performance values that have been shown to last hundreds of years in various types of building environments.
When utilizing cold-formed steel in place of structural steel or cast-in-place concrete, there can be significant cost savings due to more streamlined construction timelines with the ability for off-site prefabrication. Also, there can be significant reductions in the cost of materials due to CFS framing’s lighter weight, eliminating the need for large, costly foundations and jobsite hours.
Dimensional stability, durability, seismic performance, the highest strength-to-weight ratio of any building material, and a great reduction in heavy materials such as concrete are all great reasons to utilize cold-formed steel framing as a load bearing structural system. For example, unlike traditional wood post and beam, if a plumber cuts through a cold-formed steel post there is more likely to be only localized sagged as opposed to catastrophic failure because of the redundancies of CFS framing.
For certain cold-formed steel thicknesses (especially 20 gauge) there are multiple thicknesses that are all considered 20 gauge. This can create confusion in both the specifying and ordering of framing members. Therefore, it is better to refer to standard designators using mil thicknesses (1/1000 of an inch) or using inch thicknesses.The Edge™ Framing
Recently developed technology in the cold-formed framing industry has led to better framing member products. EQ studs have been in the framing industry for almost a decade and represent approximately 90 percent of the current market. Manufacturers like Super Stud now produce EQ studs, like the EDGE, with higher yield strength than traditional studs using less steel, which helps support the mission of sustainable construction. For more information, follow the link from The Construction Specifier.Load Bearing Systems
The code permits the floor or roof design to have a live load deflection (L/360) (1/360th of the distance between adjacent columns). In actuality, the deflection is usually closer to one-third of that. For a 30’ span, L/360 would be 1”, but what is more likely under a live load would be 1/30th inch. The exception is with snow loads, where you should allow for a full 1 inch of deflection in high-snow areas.
If you are running across a short corridor you can use a 6” or 8” stud joist member that can be used for multiple applications.
Deflection criteria includes the acceptable (allowable) flex (deflection) of a floor joist, wall stud or other framing member under load. These deflection limits are established by building codes and are expressed as a fraction. The clear span is expressed in inches (L) over the allowable deflection. As an example: a floor joist suitably designated to span 10 feet with an L/360 deflection limit will deflect no more than 120 inches / 360 (1/3 inches) under maximum design loads. Drywall or other material attached to the framing system is not likely to crack when a floor joist system deflects 1/3″. Typical examples of deflection include L/180, L/240, L/360.
All buildings must be designed to safely resist the structural loads anticipated for the life of the building. Loads can be divided into vertical loads or lateral loads. A shear wall is a general term for walls that are designed and constructed to resist racking from seismic and wind. Shear walls and braced wall panels serve the same purpose in transferring the shear (lateral loads) from the diaphragm above to the structure below while resisting racking from the lateral loads. Overall bracing of the structural to resist wind and seismic loads is often referred to as shear wall bracing.
Vertical loads act in up or down directions. In most cases the “down” loads are caused by gravity. Vertical loads are typically well accounted for in construction, but a constant challenge are lateral loads or “sideways” loads. Lateral loads act in a direction parallel to the ground and most often are the result of wind or seismic forces such as earthquakes. Lateral loads can cause structures to bend, sway, collapse, or even roll in cases where the structure is not well attached to the foundation.Curtainwall Systems
In curtainwall applications or interior non-loadbearing applications where a single-track header is not strong enough to carry the weight of the wall and cladding above it. The HJC clip allows a standard wide-flange stud member to be used over the opening rather than having to buy a special application product that can only be used for a header.Shaft Wall Systems
Shaft wall systems are a specific category of interior fire-rated partitions designed to be installed from only one side. Using very few fasteners, a CT shaft wall stud, coupled with gypsum board, tabbed track and J-runner, make safe and secure rated assemblies with up to 4-hour fire resistance. Shaft wall systems were initially developed for high-rise buildings, that needed to have enclosures around vertical chases, stairwells, and elevator shafts: as a lighter alternative to concrete masonry construction. Scaffolding up the inside of these shafts would be expensive and impractical, so every component of the shaft wall system is installed from the inside. CT stud shaft wall systems have been tested with multiple manufacturers of gypsum board liner panels, and can be used in both horizontal and vertical applications.Deflection Clips
Vertical deflection clips in a curtainwall system allows for up to 3" of total vertical movement of the floor or roof without any additional axial load on curtainwall studs themselves. The Super Stud Double Bypass and Triple Bypass clips are used to support exterior wall studs that extend past a roof or floor. The short leg is connected to the edge of the slab or perimeter beam, and standard #12 screws inserted through the patented Glide Plate™ hold the slotted leg of the clip to the exterior wall stud. Glide Plate™ provides a full ½" of bearing along each slot. The Glide Plate™ locks screws together to work as a unit distributing the load and reducing the likelihood of individual screw shear. Even if one or more screws are stripped, the Glide Plate™ allows the clip to perform almost as if no screws were stripped.Find by Application
In ASTM C754, there are three tables in the standard and three tables in the appendix for composite limiting heights. The three in the standard (tables 3, 4, and 5) are for 18 mil, 30 mil, and 33 mil, used with 5/8” gypsum board and tested in accordance with International Code Council Evaluation Service (ICC-ES) Acceptance Criteria AC86-2012. The three tables in the appendix are the same, except they are based on ½” gypsum board and tested in accordance with an earlier version of AC86.
The tables on page 19 and 20 of the SSMA catalog have exactly the same values as tables 3 through 5 in ASTM C 754, since they are based on the same test data. The only difference is that the SSMA tables include data for 27 mil material, which is not included in the ASTM tables. The ASTM tables contain only composite values based on testing.
For example, tables listed in SSMA that are not marked as composite and do not reference ICC-ES AC86 are based on calculated values of stud properties only. Each cold-formed steel framing manufacturer, including Super Stud Building Products, has their own product guide that includes tabulated data.
Soffits, horizontal corners, vertical corners, overhanging on the edge of a floor slab, going from the top of a wall that is paralleled to a truss or a beam that is just off the side of a truss or beam. The use of F-track also eliminates the need for katz blocking.
Slotted Deflection Track is engineered as a cold-formed steel top track manufactured to prevent cracking of finishes applied to interior partition framing resulting from deflection of structure above. This is achieved by fastening studs to top track through provided slots, allowing fastener vertical movement of up to 1 ½” using #8 or #10 screws by minimum 9/16” long, wafer head, self-tapping or self-drilling. You may want to consider not using slotted track where you cannot get screws in both sides.
When loaded laterally by wind or pressure against the wall surface, studs tend to want to twist. When loaded vertically from weight from above such as carrying the weight of a roof, studs tend to bow in their weak axis. Wall bracing, which can be accomplished in several different ways prevents both the bowing and twisting of studs. The most common form of wall bracing is cold roiled channel through stud punchouts, clipped to each of the studs. Wall sheathing on both flanges of the studs could also be a very effective bracing mechanism which is permitted by AISI codes.
As architects and design professionals looking to design a facility, calling for prepanelized cold-formed steel systems as early as possible is critical. The main reason to take advantage of prepanelized systems is to cut down on the amount of field construction time for cold-formed steel as well as making quality control easier on wall panel construction. If you have a fast track job that needs to be completed by a specific date such as a dormitory, school or athletic facility, panelization is a win for everyone. Also, for areas where a building needs to be enclosed before severe or adverse weather, panelization can take much of the field work into the workshop. Increased safety where work that would have been done with fall protection systems could be accomplished at a safe elevation in the shop.
Most assemblies that have double layer 5/8 board on the bottom have the resilient channel (RC) spaced at 12” on center. This provides better support than 16” on center spacing, and there is often special detailing at the butt joints at the ends of panels. This helps keep the ceiling fire protection intact longer during a fire, allowing occupants more time to escape.
It is also important to review the screw pullout and pullover capacities. For the EDGE Performance 20, the screw pullout will be 43 pounds. The concern would be the attachment of the resilient channel into the flange of the EDGE stud; not the attachment of the board to the RC.
So, if the 19 mil EQ studs are at 16” o.c., and the RC is also at 16” o.c., then the load on any one screw would be the weight of the board + insulation x 16/12 x 16/12. For a double layer of board plus fiberglass insulation, the system weight below the joist is approximately 5.5 PSF. 5.5 x 16/12 ft x 16/12 ft = 10 pounds, which is less than the 43 pounds permitted.
So, this structurally will work with the RC spaced at 16” o.c. A good recommendation however, would be to space the RC at 12” o.c., since that gives much better fire protection. If you are trying to meet a specific fire rating, make sure and follow all rated system details for installation.© 2019 by Super Stud Building Products. All rights reserved.