PC Inspection & Quality Control 2 — Questions and Answers
Question 1: During a rough-in inspection, which measurement is the inspector most likely to verify for a toilet flange?
- Height above finished floor
- Distance from the finished wall to the flange center (Correct answer)
- Diameter of the closet bend
- Depth below the subfloor
Correct answer: Distance from the finished wall to the flange center
Inspectors verify that the toilet flange center is 12 inches (or 10/14 inches for offset) from the finished wall to ensure proper toilet fit.
Question 2: Which test is required by most codes to verify the integrity of a DWV system before concealment?
- Hydrostatic pressure test at 100 psi
- Air pressure test at 5 psi for 15 minutes
- Water or air test per local code, typically at 10 feet of water head (Correct answer)
- Smoke test at 1 psi
Correct answer: Water or air test per local code, typically at 10 feet of water head
DWV systems are typically tested with water to a 10-foot head or with 5 psi air for a minimum of 15 minutes, per IPC/UPC requirements.
Question 3: An inspector finds that a horizontal drain pipe has zero slope over a 10-foot run. What is the correct action?
- Accept it if the pipe is 4 inches or larger
- Require rework to achieve the minimum ¼ inch per foot slope (Correct answer)
- Require rework to achieve ½ inch per foot slope
- Accept it because large-diameter pipes self-clean at zero slope
Correct answer: Require rework to achieve the minimum ¼ inch per foot slope
IPC and UPC require a minimum slope of ¼ inch per foot for drain pipes 3 inches and larger to ensure self-scouring flow.
Question 4: What is the primary purpose of a final plumbing inspection?
- To verify fixture rough-in dimensions only
- To confirm all fixtures are installed, functional, and the system is leak-free (Correct answer)
- To check permit fees have been paid
- To measure water pressure at the meter
Correct answer: To confirm all fixtures are installed, functional, and the system is leak-free
The final inspection confirms that all fixtures are properly installed, all connections are watertight, and the system operates as designed.
Question 5: Which condition would cause an inspector to fail a water supply rough-in inspection?
- Copper pipe supported every 6 feet horizontally
- CPVC pipe installed without expansion joints on a long run in a hot environment (Correct answer)
- PEX tubing protected with grommets through metal studs
- Pressure-reducing valve installed on the service entrance
Correct answer: CPVC pipe installed without expansion joints on a long run in a hot environment
CPVC and copper expand significantly with temperature changes; failing to allow for expansion on long runs can cause joint failures and leaks.
Question 6: When inspecting a water heater installation, which clearance is the inspector checking to prevent a fire hazard?
- Minimum 6-inch clearance from combustible walls for gas water heaters
- Minimum 12-inch clearance from combustible materials for the flue vent
- Minimum 1-inch clearance between the tank and the floor
- Minimum 18-inch clearance from the floor for the ignition source in garages (Correct answer)
Correct answer: Minimum 18-inch clearance from the floor for the ignition source in garages
In garages, water heater ignition sources must be elevated at least 18 inches above the floor to reduce the risk of igniting fuel vapors.
Question 7: An inspector notices a P-trap arm that exceeds the maximum developed length before venting. What violation does this represent?
- Trap seal loss due to self-siphoning (Correct answer)
- Excessive friction loss in the drain
- Illegal fixture unit count on the branch
- Inadequate cleanout placement
Correct answer: Trap seal loss due to self-siphoning
When a trap arm is too long, negative pressure from draining water can siphon the trap seal, allowing sewer gas into the building.
PC Inspection & Quality Control 2
During a rough-in inspection, which measurement is the inspector most likely to verify for a toilet flange?