During a renovation, a plumber needs to vent a new island sink in a kitchen. The trap arm is 1.5 inches in diameter and is located 1.2 metres from the main stack. Which of the following venting methods is most appropriate and commonly permitted by the National Plumbing Code of Canada (NPC) for this scenario?

Question: During a renovation, a plumber needs to vent a new island sink in a kitchen. The trap arm is 1.5 inches in diameter and is located 1.2 metres from the main stack. Which of the following venting methods is most appropriate and commonly permitted by the National Plumbing Code of Canada (NPC) for this scenario?

Answer options:

• Common vent
• Wet vent
• Relief vent ✅ Island fixture vent (loop vent)

Correct answer: Island fixture vent (loop vent)

Explanation: For an island sink, an island fixture vent, also known as a loop vent, is the most appropriate and commonly permitted method by the NPC. This method allows the vent pipe to rise above the fixture's flood level rim before turning down and connecting to the drainage system below the flood level rim, preventing siphoning while accommodating the island's unique installation requirements. A common vent and wet vent are not suitable for an island sink's specific layout.