Offsets of stack and vent

[sfxf]

What's design guide for offsets of stack and vent in domestic plumbing system? The house is only three-story. IPC has sections only for offsets of five stories or more.

Thanks in advance!

 

[PEDARRIN2]

The guide for the venting of offsets is because of the velocity of the water and the air carried with it. In a three story stack, you will probably not have to worry about it.

 

[ChrisConley]

Just a quick note - In a report done by Dawson and Kalinske - "Report of Hydraulics and Pneumatics of Plumbing Drainage Systems' they developed the formulae

Vt = 3.0 (q/d)^(2/5) and
Lt = 0.05(Vt)^2

Where Vt is terminal water velocity (fps), and Lt is the developed length to develop terminal velocity (ft). From these formulae it was determined for various standard pipe sizes terminal velocity is about 10-15 fps, and that this velocity is achieved within 10-15 feet of fall.

What this means is that the velocity of falling 'water' is about the same regardless if it is falling 2-3 stories, or 100 stories.