For 1 1/4 inch or larger vertical pipes, how often should they be hung per floor level?

For vertical pipes that are 1 1/4 inches in diameter or larger, the requirement is to support them at each floor level. This is essential to ensure stability and prevent undue stress on the piping system due to factors such as weight, thermal expansion, or vibration.

When pipes are installed vertically, they're subjected to various forces that can lead to sagging or misalignment if they're not adequately supported. By providing support at every floor level, you help to maintain the integrity of the system and minimize the risk of damage or failure.

The other options may not provide the appropriate support according to standard practices. Supporting at every ceiling or wall does not specifically address the load and stress factors present at floor transitions where additional support is crucial. Similarly, the requirement for support every meter does not align with the established guidelines, as it may compromise the pipe's integrity based on the distance covered in vertical runs. Supporting pipes at every floor level is therefore the appropriate choice to ensure safety, functionality, and compliance with plumbing codes.