Understanding Cold-Formed Steel Stud Spacing: 16” on Center vs. 24” on Center

When it comes to cold-formed steel (CFS) framing, engineers, architects, and builders have choices to make regarding stud spacing, most commonly 16 inches on center (o.c.) and 24 inches on center. 16” o.c. is the traditional spacing, but 24” o.c. can often be more economical and decrease construction time. The proper solution often depends on the project’s structural, financial, and performance goals.

At McClure, we are frequently asked to help clients weigh these options and optimize framing designs for efficiency and cost-effectiveness. Let’s break down the differences between these two spacing configurations, focusing on material costs, labor costs, and code provisions that support the use of 24″ o.c. The industry practice of deferred submittals creates an opportunity for contractors to change framing to 24” o.c. to reduce labor costs and decrease the project timeline.

Material Costs: Same weight in metal

One of the most significant advantages of using 24″ o.c. spacing is the reduction in the total number of studs. By increasing the distance between studs from 16″ to 24″, you need fewer studs for the same wall length- though those individual studs generally need to be heavier to make up for the fewer studs. For an efficiently designed system, that generally works out to the same weight of metal. ‘Inefficient’ designs (studs that are sized because of project specific minimums) can show significant cost savings. See case studies at the end of this article for examples.

Labor Costs: Faster Installation at 24” o.c.

Fewer studs also mean fewer installations, reducing labor costs. Framing at 24” o.c. is faster for installers to complete than at 16” o.c. because they handle fewer pieces with fewer attachments. For projects with clips, that’s 30% less clips.

It’s also not just the stud and track attachments, it’s the sheathing as well. A typical gypsum sheathing screw pattern will not change, but will be fastened to fewer studs, eliminating 30% of the screws to install and mud over.

Load Bearing: Better correlation with the floor system at 24” o.c.

Load bearing floor framing systems are often CFS joists, CFS Trusses, or another floor system that is traditionally framed at 24” o.c. already. Wall framing at 24” o.c. would allow for coordination between trades to line up this framing vertically eliminating the need for a load distributing member (LDM) on top of the wall. These LDMs are often HSS, or heavy (97mil) tracks. If studs are aligned with the floor system, the protentional for the LDM to be eliminated exists. Many contractors will choose to keep the LDM to allow the systems to not line up or permit different spacings of studs/walls.

If the LDM is kept, and walls are at 16” o.c., with floor trusses at 24” o.c., a common detail is to use a 97mil track or other heavy CFS shape to distribute the load. However, these CFS shapes are not stiff enough to always transfer that load. If a joist lands directly on top of the wall stud at 16” o.c., the wall stud is stiffer than that track vertically and will take all the load. This results in either requiring HSS LDM components on top of the wall, or designing all wall framing to be capable of supporting gravity loads at 24” o.c., with wind loading at 16” o.c. That means you are effectively paying for 24” o.c. material sizes but keeping the 16” o.c. spacing significantly increasing material costs.

Code Provisions: What the Code Says About 24” o.c.

Building codes allow for 24″ o.c. spacing provided they still meeting the performance requirements, wind loads, gravity loads, and deflection limits. There is no 16” spacing limitation imposed by the International Building Code (IBC), American Society of Civil Engineers (ASCE), American Iron and Steel Institute (AISI) codes, and those codes include many references that support the use of 24” o.c.

• Sheathed shear walls: AISI S100 and S400 capacity tables are all based on stud framing at 24” o.c., and no other capacities are provided for 16” o.c. Changing the studs from 16” o.c. to 24” o.c. has no impact on lateral design.
• Strap braced walls: AISI S100 and S400 do not rely on the intermediate wall framing to support straps. Changing the wall framing has no impact on lateral. AISI does not require the attachment of straps to studs, McClure does not recommend attaching straps to intermediate studs.
• Cladding submittals: All typical gypsum board, plywood, brick, stucco, plaster, and typical finishes are rated for spans at 24” o.c. While the precise cladding system would need to be verified for 24” o.c., there are very few systems that require 16” o.c. Most of these systems occur in Florida where cladding systems require a Florida Product Approval (FPA) full scale test. If these tests were performed on walls with 16” o.c. changing them to a different system would require a FPA submitting from an engineering design on the cladding system, or a new test of the assembly.

Energy Efficiency and Thermal Bridging

Another advantage of using 24″ o.c. spacing is improved energy efficiency. Fewer studs mean less thermal bridging, where heat is conducted through the metal studs and lost to the outside environment. By reducing the number of studs, you increase the insulation area, which can improve the wall’s overall thermal performance.

This aspect is particularly important in energy-conscious designs or in areas where codes or ownership require more stringent energy efficiency measures. Reducing the number of thermal bridges in exterior walls can make a noticeable difference in the building’s heating and cooling costs.

Acoustical Performance

Acoustical transfer between partition walls can achieve a better acoustical rating. Sounds is transmitted best through solid objects, and minimizing the amount of contract between surfaces reduces noise transfer. Consult an architect and the acoustical rating documents of the system assembly.

Fire Ratings

Most UL ratings are based on studs at 24” o.c., but if a UL rating is selected by the architect that has a specific requirement for 16” o.c., there are a plethora of alternative ULs that can be selected that would have a negligible impact on building costs. Consult the architect, UL rating documentation for the specific rating, or a fire engineer for fire rated assemblies.

Considerations

While 24″ o.c. spacing can lead to cost savings and improved energy performance, there are a few considerations to keep in mind:

• Increased loads on bridging in load bearing applications: With the bridging now spanning 24” o.c., the projects may require heavier bridging (150U075-54 instead of 150U050-54) to resist the axials and bending forces induced in the bridging, or more strong backs to relieve the bridging force.
• Long Spans, High wind High-wind zones with brittle finishes could require closer stud spacing for structural integrity. For these applications, 16″ o.c. or even tighter spacing may be necessary.
• Specifications:  Specifications may require 16” o.c. or provide no guidance. In these cases, the specification can be updated through an RFI. Unless there is a proprietary cladding system that explicitly requires 16” o.c., there is no practical reason to not accept 24” o.c.

Example Case Studies:

These are some simplistic evaluations, but give a general idea of the material implications. Openings generally reduce the effectiveness, and panelization can the effectiveness depending on panel size- thought there is almost always a material savings.

Case 1: Small load bearing building:

• Geometry: 20ftx20ft Building, 14ft tall, Load bearing building
• Loads: 20PSF Dead, 20PSF Live, 30PSF Wind
• Specification requirements: 43mil minimum, L/360 deflection limit
• Results:
  • At 16” o.c.: All Walls 600S162-43 (Note, 33mil would work, but spec limits to 43mil)
  • At 24” o.c.: All Walls 600S162-43
• This example would result in 33% less wall stud material, in addition to labor savings. This material cost is due to the specification forcing the ‘standard’ wall studs to be an inefficient size to meet the minimum requirements.

Case 2: 4 Story Load bearing building:

• Geometry: 40ftx40ft building, 4-stories 10ft tall each load bearing
• Loads: 20PSF Dead, 40PSF Live, 20psf Roof Live, 30PSF Wind
• Specification requirements: 33mil minimum, L/360 deflection limit
• Results:

• At a quick glance, the 24” o.c. looks heavier, but factoring in the spacing This is an overall 28% reduction in material weight (and presumed cost), in addition to labor savings from installing each element, and finishes to these studs. Most of the cost savings is coming from the non-bearing end walls, as due to the studs being the minimum that would be specified by the specification, are significantly (35%) more cost effective in 24” o.c., though the bearing walls are 22% more cost effective on their own.

Conclusion: Choosing the Right Stud Spacing for Your Project

Choosing between 16” o.c. and 24” o.c. spacing in cold-formed steel construction comes down to balancing material costs, labor savings, code requirements, and project-specific factors like structural loads and energy efficiency goals. At McClure, we work with our clients to evaluate these factors holistically, ensuring each project achieves the right combination of performance and cost-effectiveness.

If you’re considering Cold-Formed Steel framing for your next project, our team of Structural Engineers is here to help you navigate these choices. Contact us today to learn more about optimizing your framing design for success.