The designation “4/4” in lumber terminology indicates the nominal thickness of a board. Specifically, it refers to lumber that is nominally one inch thick when it is initially sawn. However, after the milling process, which includes surfacing and drying, the actual thickness is typically less than one inch. A common example is “4/4” lumber actually measuring around 3/4 of an inch thick after processing.
This sizing convention is important because it provides a standardized way for lumber suppliers and consumers to communicate about dimensions, facilitating consistent ordering and project planning. Historically, the practice arose from the need to account for material loss during the milling process. Utilizing a nominal size allows for efficient utilization of raw materials, balancing rough sawn dimensions with finished product requirements.
