By code, vents must be placed at least two pipe diameters from a fixture trap. In addition, the length of the trap arm is limited to the distances defined in the figure below.
Figure: Max. Distance Between Fixture Traps and Vents
Max. Distance Between Fixture Traps and Vents
|Size of Trap (in.)
||Distance from Trap (ft.)
Horizontal Vent Runs
A vent must rise at least 6 in. above the fixture flood rim before running horizontally. If necessary, a pair of 45- degree offsets may be used, as shown in the figure below.
Figure: Horizontal Offset
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