International Residential Code (IRC) Plumbing Practice Test 2026 - Free IRC Practice Questions and Study Guide

The maximum cleanout interval for building sewers smaller than 8 inches in diameter is indeed set at 100 feet according to the International Residential Code (IRC). This regulation is in place to ensure that building sewers are maintainable and accessible for proper cleaning and inspection. The cleanout intervals help facilitate the removal of blockages and allow for maintenance personnel to effectively service the plumbing system.

By establishing a 100-foot maximum cleanout interval, the code balances the need for accessibility with practical construction limits, helping to prevent excessive lengths of sewer line that could become more difficult to maintain. This distance is considered reasonable within the typical layout of residential plumbing systems, providing a manageable approach to ensuring that these lines remain functional and serviceable with minimal disruption.

The other distances mentioned do not align with the IRC guidelines for cleanout intervals in this context, which is why they are not applicable as the maximum requirement.