Sec. 28. Vent-pipe Material.—Material for vent pipes shall be of lead, brass, enameled iron or galvanized iron.
Sec. 29. Ventilation of Traps and Soil Lines.—Traps shall be protected from siphonage or air pressure by special vent pipes of a size of not less than the following tables:
| Size of pipe | Maximum length in feet | Number of traps vented | |
|---|---|---|---|
| Mains | Branch | Main vertical | |
| 11⁄4-inch vent.......... | 20 feet | 1 | |
| 11⁄2-inch vent.......... | 40 feet | 2 or less | |
| 2-inch vent.............. | 65 feet | 10 or less | 20 or less |
| 21⁄2-inch vent.......... | 100 feet | 20 or less | 40 or less |
| 3-inch vent.............. | 10 or more stories | 60 or less | 100 or less |
The branch vent shall not be less than the following sizes:
- 11⁄4 inches in diameter for 11⁄4 inch trap.
- 11⁄2 inches in diameter for 11⁄2 inch to 21⁄2 inch trap.
- 2 inches in diameter for 3 inch to 4 inch trap.
- One-half their diameter, for traps 3 inches and over.
Where two or more closets are placed side by side, on a horizontal branch, the branch line shall have a relief extended as a loop. A pipe 2 inches in diameter shall be sufficient as a loop vent for two closets. A pipe 3 inches in diameter shall be sufficient as a relief for three or four closets; and where more than four closets are located on the same branch the relief shall not be less than 4 inches in diameter. All house drains and soil lines on which a water closet is located must have a 4-inch main vent line. Where an additional closet is located in the cellar or basement, and within 10 feet of main soil or vent line, no relief vent will be required for said closet; but where it is more than 10 feet, a 2-inch vent line will be required. Relief vent pipes for water closets must not be less than 2 inches in diameter, for a length of 40 feet, and not less than 3 inches in diameter, for more than 40 feet.
No re-vent from traps under bell traps will be required.
In any building having a sewer connection with a private or public sewer used for bell-trap connections or floor drainage only, a 2-inch relief line must be extended to the roof of the building from rear end of main. House drains, constructed for roof drainage only, will not require a relief vent.
A floor trap for a shower shall be vented, unless located in the cellar or ground floor the paving of which renders the trap inaccessible.