A well-detailed cold-formed steel (CFS) framing system can accommodate forces imposed on the structure by gravity, wind uplift and seismic forces.
According to The Construction Specifier, a key element of this design is the system’s ability to account for vertical movement of structural elements like floor and roof systems by allowing them to deflect downward or upward without imposing axial loads to the wall stud members, gypsum wall boards, or other substrates.
Cold-Formed Steel Framing and Deflection
When it comes to deflection, the performance of the connections between CFS and the building structure is critically important, especially in coastal and high-seismic zones where structures face greater risk of movement, stress, and loading from natural events like earthquakes and high-velocity winds.
“Many projects require the CFS framing to allow for deflection of the primary structure in compression and/or extension,” says Chuck Webb, technical sales manager for ClarkDietrich in the Southeast and Mid-Atlantic markets.
“The movement and amount of movement should be specified by the architect or structural engineer of record,”Webb says. “From there, and based on infill or bypass wall conditions, the appropriate framing product can be identified and installed to meet the project needs.”
When it comes to deflection, the performance of the connections between CFS and the building structure is critically important.
Four Critical Connections
Critical connections occur throughout an entire structure. But, the most important are found in four crucial areas for the majority of buildings:
- Where the roof system connects to supporting walls
- At openings and headers in the wall
- Where walls connect to each other at floor levels
- Where walls connect to the foundation
Connectors, clips, or framing hardware are used to either make or support CFS, with the most common types being rigid (i.e., fixed) and deflection (i.e., movement) connectors.
“Until recently, it was common practice on CFS framing projects for installers to fabricate these types of connectors in the field using whatever scrap or stud material [they had] available,” says Larry Williams, executive director of the Steel Framing Industry Association.
“In the past few years, however, the shift to pre-engineered and pre-manufactured connectors has been gaining momentum for a number of important reasons,” says Williams.
Those reasons include a shortage of qualified installation labor, a growing shift to off-site construction processes, the growing use of CFS framing versus wood and more.
Connectors are Everything
With a building project, having the right connectors is everything.
“Everyone first thinks about the quality of the framing members, but many forget no matter how good the framing, there will definitely be problems with the overall structure and weather resistance of the construction if proper attention is not paid to the element holding everything together, says The Construction Specifier.
Recommended Resources:
- Holding it All Together: Designing, specifying, and installing connectors
- Specifying the right framing connectors for deflection