California Residential Inspector Practice Exam

If the span rating of 3/4 inch thick wood structural panels used as subfloor sheathing is 48/24, what is the maximum allowable span?

1. 20 inches

2. 24 inches

3. 28 inches

4. 32 inches

The correct answer is: 24 inches

The span rating of wood structural panels, such as those used for subfloor sheathing, indicates the maximum distance that the panels can be spaced apart while still effectively supporting load without risk of failure. The rating is expressed in two numbers, the first denoting the maximum allowable span between supports under a concentrated load (in this case, the first number being 48 means the panels can span that distance), and the second indicating the maximum span under a more uniform load (here, 24 indicating that it can span this distance). In this specific question, a span rating of 48/24 means that the panel can span a maximum of 48 inches between supports when used with a concentrated load and 24 inches when subjected to a uniform load. Since most residential construction approaches the loading conditions described by the second number (24 inches), this is considered to be the relevant span for typical applications, particularly for subfloor applications where uniform loading is likely. Thus, the maximum allowable span for the 3/4 inch thick wood structural panels used as subfloor sheathing based on the span rating provided is indeed 24 inches. This ensures that the panels provide adequate structural support and maintain the integrity of the flooring system, reducing the risk of sagging or failure