What is the maximum interval at which horizontal lead joint cast iron soil pipe exceeding five feet in length may be supported?

The maximum interval for supporting horizontal lead joint cast iron soil pipe that exceeds five feet in length is ten feet. This guideline is established to ensure that the pipes are adequately supported to prevent sagging and stress, which could lead to leaks or damage over time. Lead joint cast iron soil pipes, given their weight and material, require more frequent support compared to other types of piping to maintain structural integrity. Supporting these pipes at ten-foot intervals provides a balance between accessibility for maintenance and ensuring safety and reliability in the plumbing system.

In context, supporting pipes beyond this interval could cause undue stress on the joints, increasing the risk of failure. This regulation aligns with best practices for plumbing installation to ensure long-lasting and effective drainage systems.