The vent size is determined by the size of the

The vent size is determined by the size
of the largest drain pipe served by the
vent.

© PMA of Georgia 2010
Common Vent
VTR
V
LT
ACW
2”
1 ½”
1 ½”
2”
3”
This portion for the vent system is considered
a common vent.
The vent size is determined by the size of the
largest drain pipe served by the vent.
The portion of the pipe which serves as the
drain for the upper fixture and the vent for the
lower fixture is sized as a wet vent.
The branch drain is three inch based on
section 406.3 as amended in 2007

© PMA of Georgia 2010
Vent Sizing
VTR
VTR
SH
SH
LAV
LAV
LAV
KS
WC
WC
WC
LT
ACW
1 ½”
3”
2”
1 ½”
1 ¼”
1 ½”
3”
3”
1 ½”
3”
2”
1 ½”
3”
1 ½”
1 ½”
1 ½”
1 ¼”

© PMA of Georgia 2010
The code gives us specific application for various ways to
vent the plumbing system in a building. Some of these
we may be unfamiliar with. However all the methods in
the IPC 2006 will allow the plumbing in a building to
adequately breath. This is important, because this
breathing is what protects the seal of the trap. Protecting
the trap seal is important in helping protect occupants of
a building from hazards associated with the gasses
present in the plumbing system.
Becoming familiar with types of vents and proper sizing may
help us save money, maybe not. Proper sizing and
knowing the options available will provide opportunity for
solving problematic situations we face on a regular
basis.
Conclusion