North Carolina Building Contractor License Practice Exam

What is the actual size of a '2 x 4' dimensional lumber?

1. 1-1/2 x 3

2. 1-1/4 x 3-1/2

3. 1-1/2 x 3-1/2

4. 2 x 4

The correct answer is: 1-1/2 x 3-1/2

The actual size of a '2 x 4' dimensional lumber is typically 1-1/2 inches by 3-1/2 inches. This discrepancy between the nominal dimension and the actual size occurs because lumber is usually rough-cut in the mill and then planed down to smooth the surface and eliminate imperfections. The nominal size refers to the dimensions of the lumber before it has been dried and planed, while the actual size reflects the dimensions you will measure after this processing. In this case, while the nominal size of a '2 x 4' suggests that it measures 2 inches by 4 inches, you need to remember that once the lumber is dried and finished, it ends up measuring 1-1/2 inches by 3-1/2 inches. This standard sizing is crucial for contractors and builders as it impacts how lumber is used in construction projects.