Contributed by Michael C. Kerner
Many factors must be considered when a design specifies cold-formed steel framing members. Material selection will impact nearly every member of the construction team including the architect, engineer, specifier, code official, distributor and contractor - and could even impact the safety of building occupants. Therefore, it is imperative that there’s an understanding of requirements needed for steel framing members to be designated as code compliant.
One of the most commonly specified materials for commercial construction is steel. Generally used for both load-bearing (structural) and non-load bearing wall and floor systems (non-structural), millions of pounds of the material is used every year for the non-combustible construction of office and apartment buildings, hotels and hospitals across country.
But, how does a contractor know if the steel studs being purchased meet International Building Code (IBC) and ASTM requirements? For some products, such as fire-rated doors, this is easy because the products bear the label of a recognized third party inspection agency. For the architect, builder and general contractor, it is important that they receive the building products the specifications demand.
For metal studs, ASTM C645 (drywall framing) and ASTM C955 (structural framing) are the standards referenced in the code. These documents specify the minimum criteria for: decimal thickness, type and weight of protective coating, mechanical properties of the steel, physical configuration of the stud and labeling requirements. Without meeting all the requirements, metal studs are not code compliant.
For example, a structural load-bearing stud is required to list the “coating designator”, CP-60, in the ink jet stream and in all supporting literature. The same consideration should be given when writing the specification, the coating designator, CP-60, should be listed. All these criteria must be met for a steel stud to be code compliant.
Building Occupant Safety
In addition to the building code requirements, there is one other important issue that must be recognized by both the installer and the design professional. The use of non-compliant material can create life-safety issues. For example, if a stud is required to be a certain thickness to attain a specific limiting height and/or carry a certain load, what effect is there when a thinner metal is used than what is specified? The stud may fail and cause injury to the building occupants, or in a life-safety situation such as a fire, the rated partition may fail and it would not allow the building occupants time to escape.
It is also possible that an individual product is code-compliant, yet it will not perform as intended in a life-safety situation. As an example, a metal stud could meet the minimum requirements of ASTM C645 yet not meet the requirements of the fire-rated assembly in which it is used. How is this possible?
Word of Caution
Keep in mind that ASTM specifications are minimum requirements for the product. These requirements must be checked against the actual products used in a tested assembly. For example, the disconnect can occur when comparing building code requirements against the method in which a given fire-rated assembly must be constructed.
For example, if an architect’s partition schedule calls for UL Design U411, but only calls out the depth of the stud, then the following scenario may occur: The contractor will supply a stud that meets the project specifications, which call for the product to comply with ASTM C645. However, if the actual tested assembly were researched, it would reveal that the stud would require a return lip of 3/8 inch (10 mm). This is much larger than the 3/16-inch (5-mm) return lip C645 requires. Therefore, the partition would not meet the fire-rated assembly construction requirements. The correct products and proper assembly must be employed or life-safety issues are raised in the building. If the proper products cannot be sourced, then a different tested assembly may need to be substituted.
Knowledge of the building codes for your jurisdiction is imperative to determine if a product is code-compliant. If you are not sure, ask your manufacturer. It may take some extra time to research, but when the integrity of the products and our industry are at stake, it would certainly seem worthy of our attention.
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