Home Inspector Test Home Inspector Plumbing DWV Systems 2

Question 1

What is the minimum slope required for a 3-inch horizontal drain pipe per the International Plumbing Code?

Accepted Answer

1/8 inch per foot

Answer

A 3-inch horizontal drain requires a minimum slope of 1/8 inch per foot (approximately 1%) to ensure adequate flow.

Question 2

A home inspector observes that a toilet's wax ring seal shows signs of leakage at the floor. Which DWV component is most likely failing?

Accepted Answer

The closet flange

Answer

The closet flange connects the toilet to the drain system and supports the wax ring; flange damage or improper height causes wax ring failure and leakage.

Question 3

Which condition is considered a defect when inspecting a P-trap under a bathroom sink?

Accepted Answer

The trap outlet is higher than the trap inlet

Answer

A P-trap outlet higher than the inlet creates a 'S-trap' condition that allows siphoning and loss of the water seal.

Question 4

What does a gurgling sound from a fixture drain typically indicate in a DWV system?

Accepted Answer

Inadequate venting causing negative pressure

Answer

Gurgling at drains signals that negative pressure in the drain line is pulling air through the fixture trap, a classic sign of inadequate venting.

Question 5

Which material is NOT acceptable for use as a DWV drain pipe in residential construction under most US codes?

Accepted Answer

Galvanized steel

Answer

Galvanized steel is not approved for DWV drain applications because it corrodes internally and restricts flow; it was once used for supply lines only.

Home Inspector Test Practice Test

Home Inspector Test Practice Test

Home Inspector Test Home Inspector Plumbing DWV Systems 2