code UPDATES
2024 IBC Significant Structural Changes Wood (IBC Chapter 23)—Part 7
By John “Buddy” Showalter, PE, and Sandra Hyde, PE
T
his multi-part series discusses significant structural changes to the 2024 International Building Code (IBC) by the International Code Council (ICC). This article includes an overview of changes to IBC Chapter 23 on wood. Only a portion of the chapter’s total number of code changes is discussed in this article. More information on the code changes can be found in the 2024 Significant Changes to the International Building Code available from ICC.
Referenced Standards Figure 1. Wood structural panel wall sheathing (courtesy Norbord [David Lewis])
Table 1 provides a list of standards that are newly referenced or updated in the 2024 IBC.
speeds to be consistent with ASCE 7-22 Minimum Design Loads and Associated Criteria for Buildings and Other Structures. This change updates Wood Structural Panel Wall Sheathing the tabulated values from allowable stress design wind speeds (Vasd) to basic wind speeds (V) for consistency with ASCE 7-22. When develIBC Table 2304.6.1 provides requirements and limitations for wood oping these modifications, stud and panel capacities, nail withdrawal structural panels (WSP) used as exterior wall sheathing when resisting resistance, and nail-head pull-through capacities were evaluated in the wind pressure (Figure 1). For a given wind speed and exposure category, same manner as the previous table, resulting in comparable design the table gives the minimum nail size, WSP span rating, panel thick- requirements as the wind speeds are soft-converted from Vasd values per ness, stud spacing, and nailing schedule. The limitations of the table are IBC Section 1609.3.1. The tabulated wind speeds are also consistent that the building must be enclosed, the mean roof height must be not with those in 2021 International Residential Code (IRC) Table R602.3(3). greater than 30 feet, and the topographic factor must be equal to 1.0. Footnote “b” was updated to reference ASCE 7 Section 30.4. Since Change Significance: Tabulated values are modified for basic wind the revised table reflects basic wind speeds, the previous text in footnote “d” is no longer required but is replaced by a new note. Table 2304.6.1 Maximum Allowable Stress Design Basic Wind Speed, Vasd V, Permitted for Wood Structural Panel Wall Sheathing Used to The new footnote “d” text recResist Wind Pressures a, b, c ognizes the minimum specific Minimum Minimum Maximum Maximum Allowable Stress Design Minimum Nail Panel Nail Spacing gravity basis of 0.42 for the d Wood Nominal Wall Stud Basic Wind Speed, Vasd (mph) WSP fastener spacing and Structural Panel Spacing Edges Field provides a prescriptive option Panel Span Thickness (inches) (inches (inches Wind Exposure Category (i.e., multiply spacing by 0.67) Rating (inches) o.c.) o.c.) for framing species with lower Penetration B C D specific gravity down to a Size (inches) specific gravity equal to 0.35. 12 d 140 110 115 90 110 85 24/0 3/8 16 6 6d Engineered design of the WSP Common 1.5 fasteners is required when the 12 d 150 110 125 100 115 90 (2.0" × 24/16 7/16 16 6 specific gravity is less than 0.35 0.113") 6d 190 150 160 125 150 110 for the lumber species used for d wall framing. 12 170 130 140 110 135 105 8d Common (2.5" × 0.131")
1.75
24/16
16
6
24
6
7/16
6d
190 150
160 125
150 110
12 d
140 110
115 90
110 85
6d
140 110
115 90
110 85
b. The table is based on wind pressures acting toward and away from building surfaces in accordance with Section 30.7 4 of ASCE 7. Lateral requirements shall be in accordance with Section 2305 or 2308. d. Vasd shall be determined in accordance with Section 1609.3.1. Where the specific gravity of the wood species used for wall framing is greater than or equal to 0.35 but less than 0.42 in accordance with AWC NDS, nail spacing in the field of the panel shall be multiplied by 0.67. Where the specific gravity of the wood species used for wall framing is less than 0.35, fastening of the wall sheathing shall be designed in accordance with AWC NDS. (Footnotes “a” and “c” did not change and are not shown for brevity)
Fire Protection of Connections IBC Section 2304.10.1 provides two options for demonstrating compliance for the protection of connections in Types IV-A, IV-B, and IV-C construction: a testing option M AY 2024
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