Final answer:
Piping that penetrates through a floor should have roughly 1 inch of unthreaded pipe extending beyond the finished flooring, but local building codes should be consulted for specific requirements.
Step-by-step explanation:
In commercial construction and plumbing according to many building codes, piping that penetrates through a floor must typically leave about 1 inch of unthreaded pipe extending beyond the finished flooring. While this is a general guideline, it's important to refer to local building codes and the specific requirements of the project because there can be variations depending on the jurisdiction or the type of building. Additionally, the reason for this requirement is to ensure that there is adequate space for floor finishes and to allow for some degree of movement or expansion without affecting the pipe's integrity or causing damage to the flooring.