IPC - International Plumbing Code Sanitary Drainage Systems 2

Question 1

A plumber is installing a 6-inch horizontal building drain for a multi-story residential building. According to IPC Table 704.1, what is the minimum slope required for this pipe?

Accepted Answer

1/8 inch per foot

Answer

IPC Table 704.1 specifies that horizontal drainage pipes 4 inches and larger in diameter require a minimum slope of 1/8 inch per foot. The steeper 1/4 inch per foot minimum applies only to pipes 3 inches and smaller in diameter.

Question 2

An inspector reviewing a commercial plumbing installation finds that a sanitary tee fitting has been used to make a horizontal-to-horizontal change in direction in a drainage line. According to IPC Section 706.3, how should this be treated?

Accepted Answer

It is prohibited because sanitary tees cannot be used for horizontal-to-horizontal changes in direction

Answer

IPC Section 706.3 prohibits sanitary tees (and single sanitary tees used back-to-back) from being used as a change-in-direction fitting in a horizontal drainage application. These fittings are designed for vertical-to-horizontal transitions, not horizontal branch connections, because they do not provide the proper sweep needed for self-scouring flow.

Question 3

A trap is being installed under a lavatory in a commercial restroom. According to IPC Section 1002.3, what are the minimum and maximum allowable trap seal depths?

Accepted Answer

2 inches minimum and 4 inches maximum

Answer

IPC Section 1002.3 requires that the depth of a trap seal be not less than 2 inches and not more than 4 inches. A seal shallower than 2 inches is too easily lost to evaporation or siphonage, while one deeper than 4 inches can allow solids to accumulate and clog the trap.

Question 4

Under IPC Section 708.3.4, a cleanout is required at the base of each soil and waste stack. Which of the following also satisfies this requirement?

Accepted Answer

A wye fitting with removable plug installed at the point where the stack transitions to horizontal

Answer

IPC Section 708.3.4 requires a cleanout at or near the base of each stack. A wye fitting with a removable plug at the transition from vertical to horizontal is the standard method used to satisfy this requirement, providing direct access to clear blockages that accumulate at this high-stress location in the system.

Question 5

A building drain serving a large office complex is 6 inches in diameter. When the contractor connects this drain to the public sewer at the property line, what does IPC Section 701.2 require regarding the size of the building sewer?

Accepted Answer

The building sewer must be the same size as or larger than the building drain it serves

Answer

IPC Section 701.2 requires that the building sewer not be smaller in diameter than the building drain it serves. Reducing the sewer pipe would create a constriction that could cause backups, so the code mandates that the sewer maintain at least the same capacity as the building drain.

IPC - International Plumbing Code Practice Test

IPC - International Plumbing Code Practice Test

IPC - International Plumbing Code Sanitary Drainage Systems 2