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vent size

  1. Plumbing
    1) The plumbing codes state that when it is necessary to increase the size of a vent extension through the roof that the change in diameter must be made at least 12 inches inside the building below the roof. What is the purpose of this rule? Why can't the change be made at 3" inside the...
  2. Plumbing
    We are adding a half bath to the first floor. Lavatory drain is 1.5" and toilet drain is 3". (See attached drawing) Should I connect a vent line directly from the toilet drain to the lavatory vent in the ceiling (red line in the drawing)? If this configuration is acceptable, what size should it...
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