Journeyman Plumber ExamPlumbing Code and RegulationsEasy
A plumbing inspector is reviewing plans for a new commercial building. The plans indicate that the main building sewer will connect to the public sewer system. What is the minimum required slope for a 4-inch building sewer pipe, according to common plumbing codes like the IPC?
- A1/8 inch per foot
- B1/16 inch per foot
- C1/2 inch per foot
- D1/4 inch per foot
Show answer & explanationAnswer & explanation
Correct answer: D. 1/4 inch per foot
Proper slope is crucial for gravity-fed drainage systems to ensure adequate flow velocity for waste removal and prevent clogs. The 1/4 inch per foot is a standard minimum for 4-inch building sewers.
Why the other options are wrong
- A. While a valid slope for smaller pipes (e.g., 2-inch), it's typically insufficient as a minimum for a 4-inch building sewer.
- B. This slope is generally too shallow for a 4-inch building sewer and could lead to blockages.
- C. While this slope would work, it's steeper than the minimum required and might not be necessary, potentially leading to increased excavation costs.
Building Sewer Minimum Slope
The minimum downward angle a building sewer pipe must maintain to ensure proper drainage and prevent solids from settling.
- Varies by pipe diameter.
- Ensures self-scouring velocity.
- Critical for preventing blockages.
Memory trick: Slope it right, don't let it sit, a quarter inch for four-inch fit.