International Residential Code (IRC) Plumbing Practice Test

The requirement for adjoining walls and floor framing to extend beyond an on-site shower receptor's rough jabs is established to ensure proper support and alignment of the shower installation. This extension provides adequate clearance for the assembly of the shower and helps to prevent potential water damage to the surrounding structures by ensuring that the shower pan or receptor is well-supported and correctly positioned.

Having a 2-inch extension is crucial for a couple of reasons. First, it ensures that the framing is correctly anchored without leaving gaps that could allow water to seep into the framing, thereby maintaining the integrity of the construction. Second, this dimension allows for adequate space for tiling or other finishes around the shower which can prevent water intrusion.

While other measurements might seem practical, they may not offer the same level of structural support and waterproofing benefits that a 2-inch extension provides, ultimately safeguarding the longevity and functionality of the shower receptor installation.