Understanding AISI S400 Stud Blocking Requirements for Steel Sheet Sheathed Shear Walls

September 23, 2026 — Each month, the Cold-Formed Steel Engineers Institute (CFSEI) publishes answers to cold-formed steel (CFS) framing questions submitted through its 1-800-79STEEL hotline. This recent CFSEI FAQ addresses stud blocking requirements for steel sheet sheathed shear walls under AISI S400.

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AISI S400 Stud Blocking Requirements

Question

AISI S400-20 Table E2.3-1, shown below, addresses steel sheet sheathed shear walls.

The tabulated values are showing both a blocked and unblocked option for the steel sheet shear walls. In AISI S400 Section E2.4.1.1 note (l) is as follows:

Does the ‘Yes’ or ‘No’ for ‘stud blocking required’ from Table E2.3-1 mean you may apply the 0.7 reduction factor to the values that say ‘No’? 

For example, suppose 1870 lb/ft x 0.7 = 1309 plf, but you are unable to provide unblocked shear walls for 2085 lb/ft. Should the 0.7 factor be applied, or does the table already account for that reduction?

Answer

Table E2.3-1 does not include any unblocked values. However, there is an important distinction between panel blocking and stud blocking.

• Where the entry in the table column with the heading “Stud Blocking Required” is “Yes,” stud blocking is required
• Where the entry is “No” stud blocking is not required, but panel blocking is

The definitions of each are given in AISI S400 Section A2.1 as follows:

• Blocking, Panel: Blocking that transmits shear between the panels of a shear wall or diaphragm
• Blocking, Stud: Blocking that provides torsional support to the studs in a shear wall

All the assemblies in Table E2.3-1 require blocking. But only those values with “Yes” in the “Stud Blocking Required” column require stud blocking.

AISI S400 Section E2.4.1.1 (l) applies when panel-to-panel shear transfer is via overlapping of the sheets rather than using panel blocking (e.g., flat strap). No test data exists to confirm application of the 0.7 factor for stud-blocked assemblies with lapped panel seams. This requires engineering judgement that considers tension field force transfer across the seam.

• If you are using panel blocking (flat strap), use the values in the table directly
• If, in lieu of panel blocking, you are overlapping the panels, apply the 0.7 factor

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If you have any cold-formed steel (CFS) questions, contact CFSEI experts online or call the CFSEI Hotline at 1.800.79STEEL.

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CFSEI FAQ OF THE MONTH

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Additional Resources

• Guidance on Out-of-Plane Bracing Forces for Load-Bearing CFS Walls During CLT Floor Panel Installation
• FAQ: Does Limitation 2 of AISI S220, Section A1.2.1, Conflict with Limitation 3?
• Ask an Expert: CFSEI Responds to a Question about the Anchored Leg of a Clip Angle