Why Your Interior Cold-Formed Steel Walls May Now Require Engineering: ASCE 7-22’s Seismic Shift

Why Interior CFS Walls May Require Engineering for Seismic

Interior cold-formed steel (CFS) walls have traditionally been treated as non-structural elements, designed using prescriptive span tables based on a nominal 5 psf partition live load. However, with the release of ASCE 7-22 (Minimum Design Loads and Associated Criteria for Buildings and Other Structures), that assumption is no longer valid in much of the United States.

Chapter 13 of ASCE 7, which governs the seismic design of non-structural components, including interior partitions, has undergone significant updates. These walls, categorized under “Interior ” are now subject to revised seismic force equations and updated hazard maps. As a result, seismic forces on interior CFS walls have increased more than 208% compared to ASCE 7-16.

This shift has major implications: in many regions, seismic loading may now control the design of interior walls, requiring engineering input where none was previously needed.

What Changed in ASCE 7-22

ASCE 7-22 introduces two major changes that affect the seismic loading on interior walls:

a. Revised Seismic Force Equations

Chapter 13 now includes adjusted amplification factors, modified response coefficients, and explicit height amplification based on the building’s seismic system. These changes result in higher calculated forces for many non-structural components, including interior walls.

b. Updated Seismic Hazard Maps

The seismic hazard maps in ASCE 7-22 reflect updated ground motion models, increasing Ss and S1 values in many parts of the U.S. This alone can significantly raise the base seismic demand, even in areas not traditionally considered high-risk.

Design Implications

The increased seismic forces have the potential to govern the strength design of interior CFS walls. However, it’s important to understand that seismic loads are classified as extreme events and do not factor into deflection checks. This means:

• Strength checks may now be controlled by seismic rather than live load.
• Deflection criteria may still be governed by the interior 5psf.
• Engineering evaluation may be required to verify strength compliance, even if the wall framing does not ultimately change sizes.
• Connection detailing may need to be upgraded to resist higher seismic forces.

What Architects and Contractors Need to Know

The seismic design changes introduced in ASCE 7-22 have real-world consequences for project planning, coordination, and execution:

Standard 5 psf span tables may no longer apply in seismic regions. Interior walls may now require stamped engineering, even if non-load-bearing. This has cost and schedule implications.

For Architects

Collaborate early with your Engineer of Record (EOR) to determine whether seismic forces govern the design of interior walls. If so, you may need to:

• Provide detailed specifications for seismic performance of interior components.
• Include delegated design requirements for interior framing in your construction documents.
• Clearly communicate expectations to contractors to ensure code compliance and avoid scope gaps.

For Contractors

Carefully review project specifications to determine whether a delegated design is required for interior walls. If your project is located in a seismic region (see figure below), consider:

• Engaging an engineer early, even if not explicitly required by your project’s specification, to avoid mid-project changes.
• Verify whether traditional 5 psf span tables are still applicable.
• Consult with your engineering partner or reaching out to McClure to understand how these changes may affect material sizes and detailing requirements.
• Proactively addressing these issues can help prevent unexpected costs, delays, and compliance challenges during construction.

Why This Is Changing

The motivation behind the increased seismic demands in ASCE 7-22 stems from a growing recognition of the economic and functional impact of non-structural component failures during earthquakes. While structural systems protect life safety, non-structural elements, like partitions, often account for the majority of economic losses in earthquakes. These failures can lead to costly repairs, business interruptions, and extended downtime for buildings that remain structurally sound.

As highlighted by Kirsten Zeydel, S.E. of Nevell Group during her presentation at the 2025 CFSEI Expo in Raleigh, the 208% increase in seismic forces on interior walls reflects an intentional shift to limit costly and disruptive non-structural damage. This change is not just about code compliance—it’s about improving building resilience and reducing long-term risk.

Who Is Affected

These seismic design changes apply to all buildings classified in Seismic Design Categories C, D, E, and F. Importantly, they may also impact buildings in Seismic Design Category B. Categories B and C represent regions that have traditionally not required seismic detailing for interior non-structural walls. As a result, this update represents a significant shift for those areas, where interior wall engineering may now become necessary for code compliance.

It’s important to note that ASCE 7-22 is referenced by the 2024 International Building Code (IBC). These changes will only take effect once a jurisdiction formally adopts IBC 2024. Until then, projects will continue to follow the seismic provisions of ASCE 7-16 (or earlier), depending on the local code cycle.

Figure 1 – Areas where seismic loading has the potential to exceed 5psf for typical interior Cold formed steel (h>9ft) wall assemblies.

Assumes: I_P = 1.0, W_P = 10 psf, H_f = 3.5, R_μ = 1.3

 Conclusion

ASCE 7-22 represents a significant shift in how we approach the design of interior cold-formed steel walls. What was once a prescriptive, low-risk element may now require detailed engineering analysis in a significant portion of the county. This has to potential to affect connections, members, and braces.

By understanding these changes and planning accordingly, architects and contractors can ensure code compliance, avoid costly surprises, and continue delivering safe, efficient buildings.

Technical Note:

The figure presented is a simplified representation of regions where seismic forces may exceed the standard 5 psf interior live load. It is intended to prompt discussion with a qualified engineer, not to serve as a definitive design tool. Below is a summary of the rationale:

Load Combination Basis

ASCE 7-22 §2.4.5 (9) includes seismic and live loads in the combination: 1.0D + 0.525Ev + 0.525Eh + 0.75L + 0.1S

For interior wall flexural analysis, assuming only seismic and live loads apply: 0.525Eh + 0.75L

To exceed a 5 psf live load, Eh must be ≥ 2.38 psf.

Seismic Force Calculation

Using: ASCE Eq. 13.3-1   

Assumptions:

=10psf (typical wall weight: drywall, studs, collateral)

, (standard importance factor)

=1+2.5(Z/H)=3.5, (based on Z/H = 1.0, conservative)

=1.3 (unknown seismic system, conservative)

=1.4, =1.5, (ASCE 7-22 Table 13.5-1 for light-frame walls >9 ft)

An of 0.237 corresponds to the middle of Seismic Design Category B per ASCE 7-22 Table 11.6-1. This means that even in moderate seismic regions, interior wall seismic forces may exceed the traditional 5 psf live load—potentially triggering engineering requirements – though there are several conservative assumptions in this that your structure may not fall under.