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Plumber Red Seal · Question

A plumber is roughing in a stack vent for a multi-storey residential building. The building has a 102 mm (4 inch) soil stack. What is the minimum required diameter for the stack vent extending through the roof, according to the National Plumbing Code of Canada?

According to the National Plumbing Code of Canada, a stack vent that serves a soil or waste stack exceeding 76 mm (3 inch) in diameter must be at least 76 mm (3

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Question: A plumber is roughing in a stack vent for a multi-storey residential building. The building has a 102 mm (4 inch) soil stack. What is the minimum required diameter for the stack vent extending through the roof, according to the National Plumbing Code of Canada?

Answer options:

  • 38 mm (1 1/2 inch)
  • 51 mm (2 inch)
  • 64 mm (2 1/2 inch) ✅ 76 mm (3 inch)

Correct answer: 76 mm (3 inch)

Explanation: According to the National Plumbing Code of Canada, a stack vent that serves a soil or waste stack exceeding 76 mm (3 inch) in diameter must be at least 76 mm (3 inch) in diameter. The vent should not be reduced below half the diameter of the stack served, and never less than 38 mm.

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