Originally posted at BuildSteel.org
How does cold-formed steel (CFS) compare to cast-in-place concrete when framing a building? Neither material has the monopoly on benefits. The “best” material depends on the project.
For example, the stiffness and heavy weight of concrete provides resistance to deflection and overturning due to wind loads, which are often important factors in the design of slender, high-rise buildings. On the other hand, CFS has design and construction advantages, and it is cost-effective in low and mid-rise construction.
Let’s take a further look. Here’s how CFS and cast-in-place concrete compare in four key areas.
1. Strength-to-weight ratio
According to the Steel Framing Alliance (SFA), cold-formed steel has the highest strength-to-weight ratio of any construction material.
Due to its high strength and light weight, less weight of CFS material is required to carry the same structural load as concrete. Here’s how it works:
- The CFS framing system’s lighter weight (i.e., dead load) calls for smaller foundations with less concrete to support the structure. That means the foundation for a CFS structure can cost considerably less than a comparable concrete
Lightweight flooring systems
CFS’s high strength-to-weight ratio also benefits the design of flooring systems:
- A designer might choose a flooring system comprised of cold-formed steel composite deck with structural concrete fill. This type of system would provide a solid concrete deck option. However, because of the relatively heavy weight of the concrete, such systems are often limited to about eight stories when used in combination with a CFS load-bearing wall system.
- As an alternative, a lower profile cold-formed steel deck with a self-leveling gypsum-based product, one that sets up to 3,500 psi, provides a solid concrete feel, and keeps the flooring system lightweight, allowing CFS load bearing wall systems to be used for taller buildings.
2. Off-site construction
Unlike cast-in-place concrete, CFS components can be assembled off-site. This is ideal for mid-rise construction, which tends to involve designs with identical, repetitive sections.
Cuts man-hours, waste
Off-site construction or prefabrication of CFS walls, subfloor systems, and trusses:
- Reduces the labor cost required to assemble the structural framing system
- Reduces construction waste
- Minimizes costly weather delays
- Ensures greater quality control
- Reduces builder’s risk
- Increases speed of construction