How big a hole can be cut into a cold-formed steel (CFS) stud without compromising its performance?
That’s an important question. A mechanical trade’s crews, for example, might cut, notch or bore holes into CFS framing members. Those holes and cuts can have a big effect on stud performance.
Cutting and notching impacts a CFS stud’s:
- Fastening area
- Axial capacity
- Shear and web crippling strength
- Bending strength
- Bending stiffness
CFS studs are manufactured with and without factory punch-outs. It’s best to use these than to cut or notch holes on your own.
How much material can be removed?
So, just how much material can be removed from metal studs without compromising their integrity?
The Cold-Formed Steel Engineers Institute has an answer in CFSEI Tech Note G500-11 (“Guidelines for Inspecting Cold-Formed Steel Structural Framing in Low Rise Buildings”). Under section 1.0 Materials, paragraph 1.3 Web Holes, CFSEI Tech Note G500 says this:
- “The size of a web hole should not be larger than one-half the web depth, or 2-½” maximum in the web direction and not more than 4-½” long in the member direction.”
The Code Compliance Research Report, CCRR-0224, from Intertek says the same in paragraph 3.2:
- “Web punch-out widths shall not exceed 2.5 inches, or half of the member depth. Web punch-out length shall not exceed 4.5 inches.”
The ICC Evaluation Service, a subsidiary of the International Code Council, recommends a smaller hole limit:
- 1-½”, according to the ICC-ES Evaluation Report, ESR-4205.
Pat Ford, Steel Framing Industry Association (SFIA) technical director, says that a few limited holes within CFS studs may be safely executed in the field. But, those cut studs will still need a thorough engineering review, he says. Some may need to be replaced.
Use factory punch-outs on CFS studs
The wise course is to use factory engineered punch-outs in CFS studs, rather than cut or notch studs in the field.
Metal framing contractors don’t generally notch or bore holes into CFS studs anyway. They install studs as they come from the factory. And many stud products have punch-outs to accommodate bridging members, as well as electrical, plumbing and HVAC elements.
Factory produced punch-outs can prevent random notching or boring that could otherwise compromise the integrity of the stud.
Additional Resources
- Sorting Apples from Oranges — Comparing Evaluation Services with Third-Party Certification
- SFIA Releases Guide to the Performance-Based Nonstructural Partition Selection of Metal Framing
- SFIA Releases Updated Technical Guide with the Most Up-to-Date CFS Load and Span Tables in the Industry
- 5 Need-to-Knows about Building Codes and Cold-Formed Steel