Red Seal Plumbing Practice Exam

The minimum size of a plumbing vent serving a typical basement three piece plumbing rough-in with a developed length of 12 meters is 1 1/2 inches. This is because the minimum size requirement for a vent is based on the fixture drain it serves, and a basement three piece plumbing rough-in typically includes a toilet, sink, and shower/tub which all have a drain size of 1 1/2 inches. Option A, 1 inch continuous vent, is too small and may cause clogs in the vent, leading to drainage issues. Option C, 2 inch continuous vent, is larger than the required size and may not fit in the limited space of a basement. Option D, 3/4 inch continuous vent, is also too small and may not provide adequate ventilation for the plumbing system. Therefore, option B is the most appropriate and correct answer for this question