Which type of lumber is classified as heavy timber based on its smallest dimension?

Heavy timber is specifically characterized by its dimensions, with the classification typically requiring a minimum smallest dimension of 6 inches. However, for lumber to be classified as heavy timber, it is essential that the smallest dimension, intended for structural elements, is 8 inches or more. This sizing provides significant fire resistance and structural integrity, making heavy timber components distinct in their ability to withstand fire and collapse compared to standard lumber. This classification reflects building codes and fire safety standards that recognize heavier timber as a safer option for certain structural applications. Given this context, lumber with a smallest dimension of 8 inches meets the criteria for heavy timber classification.