North Carolina Building Contractor License Practice Exam

What is the actual size and weight of a standard 8" x 8" x 16" concrete masonry unit?

1. 7.5" x 7.5" x 15.5" - 40 lbs

2. 8" x 8" x 16" - 30 lbs

3. 7.5" x 7.5" x 16" - 50 lbs

4. 8" x 8" x 16" - 35 lbs

The correct answer is: 7.5" x 7.5" x 15.5" - 40 lbs

The correct choice reflects the actual size and typical weight associated with concrete masonry units (CMUs). Standard concrete blocks, often referred to as cinder blocks or masonry units, have nominal dimensions that can differ from their actual measurements due to manufacturing tolerances and the need for mortar joints in construction. For a standard 8" x 8" x 16" block, actual dimensions are generally about 7.5" x 7.5" x 15.5". This reduction accounts for the necessary space for mortar, which is why builders and architects often work with nominal sizes. As for the weight, a standard concrete masonry unit typically weighs around 40 lbs, providing a solid balance between durability and manageability for construction purposes. This weight is consistent with the density of the concrete used in their manufacturing process. Understanding the difference between nominal and actual sizes is important for anyone involved in construction, as it affects the layout and structural integrity of the building. It is crucial to be aware of these specifications when designing or constructing walls to ensure accuracy in measurements and material usage.