ICC 400-2022: Standard on the Design and Construction of Log Structures

This standard provides the minimum design requirements for new log structures, including structural, thermal envelope and fire-resistance provisions.

Notable changes from the 2017 edition include:

• New tabulated reference provides the weight per square foot of wall surface area of log-walls at 21-percent design moisture content by average width and specific gravity. Additional factors noted to adjust moisture content and/or nominal size/ shape to average width.
• Section 302.2.4 Notching and boring: Now provides multiple paths (e.g., prescriptive, calculated) for acceptance of notching and boring of beams. Two new illustrations replace Figure 302.2.4.
• Section 302.3 Mechanical connections and fasteners: Updated prescriptive path compliance for ANSI/AWC specification in the National Design Specification (NDS), alternative evaluation path for proprietary (nonconforming) fasteners, and specified analysis for wood dowels.
• New tabulated reference providing the bearing capacity (lb/in) of wall-logs, which is useful for calculating the continuous load path.
• Updated US Climate Zone map to reflect updates in the 2021 IECC.
• Improved criteria for settling devices to ensure structural integrity.
• Section 305 Thermal envelope: Updated to clarify the relationship to infiltration (Section 306) and the relationship to the 2021 IECC Commercial and Residential provisions.
• Table 305.3.1.1: Updated to ½-inch average width increments and notes for modification of U-factor based on shape and climate zone. Table 305.3.1.2: Updated to show prescriptive compliance options given a minimum average log-wall thickness.