IPC 909.1 / Table 909.1
What it means on the job
For a 1-1/2" trap arm, the maximum distance to the vent is 6 feet per IPC Table 909.1 (Distance of Trap From Vent, Section 909). At exactly 6 feet, this installation is at the maximum but still within code. The slope of 1/4" per foot is the minimum required for pipes smaller than 3 inches. The critical concern is that the pipe fall over 6 feet (1.5 inches total) does not drop the trap arm below the trap weir level.
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Related IPC sections
IPC 905.2
The vent connection must be above the trap weir (the overflow point of the trap). Connecting below the weir makes it a wet vent carrying waste, not a true vent, and will not properly protect the trap seal.
IPC 905.5
Vent pipes must rise vertically to a point at least 6 inches above the flood-level rim of the highest fixture served before turning horizontal. This prevents waste from backing up into the vent.
IPC 906.2
Crown venting (connecting the vent at the top of the trap) is prohibited because it creates a cross-connection path and can siphon waste into the vent. The vent must connect to the trap arm downstream of the trap.
IPC 912
Wet venting is permitted by IPC Section 912 (Wet Venting) when properly configured. The wet vent must be at least 2 inches and serve as both drain and vent for bathroom group fixtures. The dry vent portion must connect at or above the highest fixture drain, and the wet vent receives fixtures in a top-to-bottom arrangement. This bathroom group configuration is a common and compliant wet vent layout.
IPC 917
AAVs are permitted by the IPC when a conventional vent is not feasible, provided: the AAV is listed (ASSE 1051), installed at least 4 inches above the fixture drain, within the maximum developed length of the trap arm, accessible for service, and the building has at least one conventional vent stack open to atmosphere. This installation meets all requirements.
IPC Section 604.8
This passes code. IPC Section 604.8 requires that water pressure at any fixture not exceed 80 psi. The system design maintains maximum 75 psi at the lowest fixture in each zone, which is within the 80 psi limit. The lowest zone (floors 1-12) at 65 psi from city main pressure does not need a PRV since it already falls below 80 psi at all fixtures. The three upper zones each have PRV stations that reduce the booster pump output pressure to appropriate zone pressures. This is a well-designed high-rise plumbing system that properly addresses the 0.433 psi per foot of elevation head that makes pressure management essential in tall buildings.
CraftIQ explanations are original educational commentary written in trade language and verified against the cited standards. Always confirm requirements against the code edition adopted by your jurisdiction — this is training material, not a substitute for the code book or your AHJ.