Standpipes shall be supported at which of the following points?

Standpipes are crucial components of fire protection systems and must be correctly supported to ensure proper functioning and safety. The correct choice emphasizes the need to support standpipes at the highest level and then at every other floor. This approach helps manage the weight of the piping and any potential stresses or forces acting on it due to fluid dynamics when the system is in use.

Supporting the standpipe at the highest level protects against flexing or sagging that could occur if the standpipe were only anchored at the bottom or at less frequent intervals. Additionally, providing support on alternating floors distributes the load evenly and allows for effective management of thermal expansion and contraction, which can occur with temperature fluctuations in the system.

This method of support aligns with established codes and standards, ensuring the structural integrity and operational reliability of the standpipe system. Properly supported standpipes also help facilitate ease of maintenance and inspection, reducing the risk of system failure during emergency situations.