What type of piping can be attached directly to walls without additional support as per plumbing codes?

The choice of 1-inch CPVC piping as the correct answer is based on plumbing codes that stipulate specific guidelines for various types of piping materials and their installation requirements. CPVC (chlorinated polyvinyl chloride) piping is lightweight and has sufficient rigidity to be mounted directly to walls without requiring additional supports for specific sizes, such as the 1-inch diameter.

This capability aligns with the general practices outlined in plumbing codes, which allow CPVC piping to be securely attached to solid surfaces in residential and commercial applications. The 1-inch size is particularly manageable for installation purposes, granting flexibility in various plumbing configurations without the necessity of excessive bracing or support.

In contrast, larger or heavier pipes, such as 2-inch PVC, 1 1/2-inch copper, or 3-inch cast iron pipes, generally do require additional support to prevent sagging or movement under their weight. Adhering to these regulations is crucial in maintaining a safe and effective plumbing system, ensuring that installations are durable and compliant with building safety standards.