North Carolina General Contractors Practice Exam

What are the actual dimensions of a standard CMU?

1. 7 1/2" x 7 1/2" x 15 1/2"

2. 7 5/8" x 7 5/8" x 15 5/8"

3. 7 3/4" x 7 3/4" x 15 3/4"

4. 7" x 7" x 16"

The correct answer is: 7 5/8" x 7 5/8" x 15 5/8"

The actual dimensions of a standard Concrete Masonry Unit (CMU) are typically 7 5/8 inches by 7 5/8 inches by 15 5/8 inches. These measurements reflect the nominal dimensions used in construction, which include the thickness of mortar joints. The nominal size is larger due to the fact that it accounts for the added mortar applied between the blocks during construction, which allows for tighter construction practices and better alignment. Understanding the actual size is essential for contractors as it directly impacts structural calculations, material purchases, and overall construction processes. Knowledge of these dimensions helps ensure that projects remain within design specifications and that materials fit properly. The other options present dimensions that do not align with the industry standards for CMUs, making them less applicable for general contracting work requiring accuracy in material specifications. For example, dimensions such as 7 1/2 inches or 7 inches do not reflect the common sizes recognized in building codes and industry practices.