The Ontario Building Code | Vent Stacks, or Stack Vents
7.5.8.4. vent Stacks, or Stack vents
(1) A vent stack, or stack vent shall be sized in accordance with Table 7.5.8.4. based on,
(a) the length of the vent stack or stack vent, and
(b) the total hydraulic load that is drained to the lowest section of soil or waste stack or stacks served by the vent pipe, plus any additional vent loads connected to the vent stack or stack vent.
Table 7.5.8.4.
Size and Developed Length of Stack vents and vent Stacks
Forming Part of Sentence 7.5.8.4.(1)
| Column 1 | Column 2 | Column 3 | Column 4 | Column 5 | Column 6 | Column 7 | Column 8 | Column 9 | Column 10 | Column 11 | Column 12 | Column 13 | |
| Size of soil or Waste Stack, in. | Total Hydraulic Load Being vented, fixture units | water OccupiedArea |
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| 1¼ | 1 ½ | 2 | 3 | 4 | 5 | 6 | 8 | 10 | 12 | |
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| 1¼ | 2 | 0.29 | 9 | NL | NL | NL | NL | NL | NL | NL | NL | NL | |
| 1½ | 8 | 0.25 | 15 | 46 | NL | NL | NL | NL | NL | NL | NL | NL | |
| 2 | 12 | 0.25 | 9 | 23 | 61 | NL | NL | NL | NL | NL | NL | NL | |
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| 24 | .29 | 8 | 15 | 46 | NL | NL | NL | NL | NL | NL | NL | |
| 3 | 10 | 0.15 | NP | 13 | 46 | 317 | NL | NL | NL | NL | NL | NL | |
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| 21 | .20 | NP | 10 | 33.5 | 247 | NL | NL | NL | NL | NL | NL | |
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| 53 | .25 | NP | 8 | 28.5 | 207 | NL | NL | NL | NL | NL | NL | |
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| 102 | .29 | NP | 7.5 | 26 | 189 | NL | NL | NL | NL | NL | NL | |
| 4 | 43 | 0.15 | NP | NP | 10.5 | 76 | 299 | NL | NL | NL | NL | NL | |
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| 140 | .20 | NP | NP | 8 | 61 | 229 | NL | NL | NL | NL | NL | |
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| 320 | .25 | NP | NP | 7 | 52 | 195 | NL | NL | NL | NL | NL | |
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| 540 | .29 | NP | NP | 6.5 | 46 | 177 | NL | NL | NL | NL | NL | |
| 5 | 190 | 0.15 | NP | NP | NP | 25 | 97.5 | 302 | NL | NL | NL | NL | |
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| 490 | .20 | NP | NP | NP | 19 | 76 | 232 | NL | NL | NL | NL | |
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| 940 | .25 | NP | NP | NP | 16 | 64 | 204 | NL | NL | NL | NL | |
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| 1 400 | .29 | NP | NP | NP | 15 | 58 | 180 | NL | NL | NL | NL | |
| 6 | 500 | 0.15 | NP | NP | NP | 10 | 39.5 | 122 | 305 | NL | NL | NL | |
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| 1 100 | .20 | NP | NP | NP | 8 | 30.5 | 94.5 | 238 | NL | NL | NL | |
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| 2 000 | .25 | NP | NP | NP | 6.5 | 25.5 | 79 | 201 | NL | NL | NL | |
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| 2 900 | .29 | NP | NP | NP | 6 | 23.5 | 73 | 183 | NL | NL | NL | |
| 8 | 1 800 | 0.15 | NP | NP | NP | NP | 9.5 | 29 | 73 | 287 | NL | NL | |
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| 3 400 | .20 | NP | NP | NP | NP | 7 | 22 | 58 | 219.5 | NL | NL | |
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| 5 600 | .25 | NP | NP | NP | NP | 6 | 19 | 49 | 186 | NL | NL | |
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| 7 600 | .29 | NP | NP | NP | NP | 5.5 | 17 | 43 | 170.5 | NL | NL | |
| 10 | 4 000 | 0.15 | NP | NP | NP | NP | NP | 9.5 | 24 | 94.5 | 292.5 | NL | |
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| 7 200 | .20 | NP | NP | NP | NP | NP | 7 | 18 | 73 | 225.5 | NL | |
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| 11 000 | .25 | NP | NP | NP | NP | NP | 6 | 15.5 | 61 | 192 | NL | |
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| 15 000 | .29 | NP | NP | NP | NP | NP | 5.5 | 14 | 55 | 174 | NL | |
| 12 | 7 300 | 0.15 | NP | NP | NP | NP | NP | NP | 9.5 | 36.5 | 116 | 287 | |
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| 13 000 | .20 | NP | NP | NP | NP | NP | NP | 7 | 28.5 | 91 | 219.5 | |
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| 20 000 | .25 | NP | NP | NP | NP | NP | NP | 6 | 24 | 76 | 186 | |
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| 26 000 | .29 | NP | NP | NP | NP | NP | NP | 5.5 | 22 | 70 | 152 | |
| 15 | 15 000 | 0.15 | NP | NP | NP | NP | NP | NP | NP | 12 | 39.5 | 94.5 | |
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| 25 000 | .20 | NP | NP | NP | NP | NP | NP | NP | 9.5 | 29 | 73 | |
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| 38 000 | .25 | NP | NP | NP | NP | NP | NP | NP | 8 | 24.5 | 62 | |
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| 50 000 | .29 | NP | NP | NP | NP | NP | NP | NP | 7 | 22.5 | 55 | |
Notes to Table 7.5.8.4.:
(1)NL means not limited.
(2)NP means not permitted.
(2) For the purposes of Table 7.5.8.4., the length of a stack vent or vent stack shall be its developed length from its lower end to open air.
(3) The minimum size of vent stack or stack vent shall be one-half the size of the soilor waste stack at its base.
(4) A stack vent serving a wet vent stack that is over 4 storeyshigh shall extend the full size of the wet vent to open air.
(5) Every sanitary building drain shall be provided with at least one vent that is not less than 3 in. in size.