The Ontario Building Code | Location of Vent Pipes
7.5.6.3. Location of vent pipes
(1) Except as provided in Sentences (2) and (3), a vent pipe that protects a fixture trap shall be located so that,
(a) the developed length of the trap arm is not less than twice the size of the fixture drain,
(b) the total fall of the trap arm is not greater than its inside diameter, and
(c) the trap armdoes not have a cumulative change in direction of more than 135°.
(2) The trap arm of water closets, S-trap standards or any other fixturethat also discharges vertically and depends on siphonic action for its proper functioning shall not have a cumulative change in direction of more than 225°.
(3) A vent pipe that protects a water closet or any other fixture that also depends on siphonic action for its proper functioning shall be located so that the distance between the connections of the fixture drain to the fixture and the vent pipe shall not exceed,
(a) 1 000 mm in the vertical plane, and
(b) 3 m in the horizontal plane.
(4) The maximum length and minimum slope of every trap arm shall conform to Table 7.5.6.3.
Table 7.5.6.3.
Length of Trap Arm
Forming Part of Sentence 7.5.6.3.(4)
| Item | Column 1 Size of Trap Served, in. | Column 2 Maximum Trap Arm, m | Column 3 Minimum Slope |
| 1. | 1 ¼ | 1.5 | 1 in 50 |
| 2. | 1 ½ | 1.8 | 1 in 50 |
| 3. | 2 | 2.4 | 1 in 50 |
| 4. | 3 | 3.6 | 1 in 50 |
| 5. | 4 | 4.9 | 1 in 50 |
| 6. | 4 | 9.8 | 1 in 100 |
(5) The vent pipe from a water closet or any other fixture that has an integral siphonic flushing action may be connected to the vertical legof its drainage pipe.