All soil and waste stacks and branches shall be provided with correctly faced inlets for fixture connections.
In existing buildings where the soil or waste vent pipe is not extended undiminished through or above the roof or where there is a sheet metal soil or waste vent pipe and the fixture is changed in style or location or is replaced, a soil or waste vent pipe of the size and material prescribed for new work shall be installed.
No fixture connection shall be made to a lead bend or branch of a water closet or similar fixture. No soil or waste vent, circuit or loop vent above the highest installed fixture on the branch or main shall hereafter be used as a soil or waste pipe.
No soil or waste stack shall be installed or permitted outside of the building unless adequate provision is made to protect it from frost.
All roof extensions of soil and waste stacks shall be run full size at least one foot above the roof, and when the roof is used for other purposes than weather protection, such extension shall be not less than seven feet above the roof.
When there is danger of frost closure, no roof extension shall be less than four inches in diameter. Change in diameter shall be made by use of a long increaser at least one foot below the roof, and where access to the roof is difficult, a test opening shall be provided at this point.
The roof terminal of any stack or vent, if within 12 feet of any door, window, scuttle or air shaft, shall extend at least three feet above the same.
Any vertical branch rising more than 10 feet or any lateral branch running more than 25 feet from the main soil line shall be continued full size to a point above the roof in the same manner as required for main soil pipes or may be returned to the main vent pipe full size.
Every fixture trap shall be protected against siphonage and back pressure and air circulation assured by means of a soil or waste stack vent and continuous waste or soil vent or a loop or circuit vent. No crown vent shall be installed.
No trap shall be placed more than five feet, horizontal developed length, from its vent, except that the distance between the vent and trap may be 15 feet or less on the waste from a surgical operating table, dental cuspidor or other similar fixture. The distance shall be measured along the central lines of the waste or soil pipe, from the vertical inlet of the trap to the vent opening. The vent opening from the soil or waste pipe, except for water closets and similar fixtures, shall not be below the dip of the trap.
All main vents or vent stacks shall connect full size at their base to the main soil or waste pipe at or below the lowest fixture branch and shall extend undiminished in size above the roof or shall be reconnected with the main soil or waste vent at least three feet above the highest fixture branch.
All vent and branch vent pipes shall be free from drops or sags and be so graded and connected as to drip back to the soil or waste pipe by gravity. Where vent pipes connect to a horizontal soil or waste pipe, the vent branch shall be taken off above the center line of the pipe, and the vent must rise vertically or at an angle of 45º to the vertical to a point six inches above the fixture it is venting before offsetting horizontally or connecting to the branch, main waste or soil vent.
Where bathrooms or waterclosets or other fixtures are located on opposite sides of a wall or partition or directly adjacent to each other within the prescribed distance, such fixtures may have a common soil or waste pipe and common vent.