5×18

5×18 refers to a standard size for lumber, specifically meaning a piece of wood that is nominally 5 inches wide and 18 feet long. In actual dimensions, dressed lumber is typically smaller than its nominal size due to milling and drying processes. Therefore, a 5×18 board would likely measure closer to 4.5 inches in width and 17.5 feet in length, though actual dimensions can vary by manufacturer and specific grade. This size is often used in construction for framing, sheathing, and other structural applications. The "5×" dimension indicates the thickness and width, while the "18" indicates the length. Lumber dimensions are usually stated in inches and feet, respectively, with the width preceding the length. This particular size would be considered a relatively long and moderately wide board, offering versatility for various building projects where longer spans or larger surface areas are required.