What are the nominal dimensions of a standard masonry block?

The nominal dimensions of a standard masonry block are recognized as 8 inches by 8 inches by 16 inches. This specific sizing has become widely accepted in the industry as the standard for concrete masonry units (CMUs).

The 8 by 8 by 16 dimensions reflect the nominal terms used in masonry, which allows for the addition of mortar thickness when calculating the actual dimensions upon installation. In reality, due to the mortar joints, the actual size of the block is slightly smaller, typically measuring 7 5/8 inches by 7 5/8 inches by 15 5/8 inches. This distinction between nominal and actual dimensions is crucial as it guides builders in the planning and execution of masonry walls.

Understanding these dimensions is essential for construction professionals, as they impact project estimating, the number of blocks needed, and ultimately how the structures will be framed.