Plumber Red Seal · Question
A plumber is extending a branch vent from a water closet and a lavatory. The vent piping must connect to a main vent or vent stack. According to the National Plumbing Code of Canada, what is the minimum required size for a branch vent serving a single water closet (4 DFU) and a single lavatory (1 DFU) if the total developed length is less than 15 m?
Based on NPC Table 2.5.8.1. (or similar provincial tables for vent pipe sizing), the minimum size for a branch vent is determined by the total drainage fixture
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Question: A plumber is extending a branch vent from a water closet and a lavatory. The vent piping must connect to a main vent or vent stack. According to the National Plumbing Code of Canada, what is the minimum required size for a branch vent serving a single water closet (4 DFU) and a single lavatory (1 DFU) if the total developed length is less than 15 m?
Answer options:
- 32 mm ✅ 38 mm
- 51 mm
- 64 mm
Correct answer: 38 mm
Explanation: Based on NPC Table 2.5.8.1. (or similar provincial tables for vent pipe sizing), the minimum size for a branch vent is determined by the total drainage fixture units it serves and its developed length. For a total of 5 DFU (4 DFU for water closet + 1 DFU for lavatory) and a developed length less than 15 m, a 38 mm vent pipe is typically required.
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