Vent pipe size for toilet

jackyyboy · 03-06-2010, 01:20 PM

Hi, I'm installing an all new DWV system in a remodel. An inspector said that a 3" drain on a toilet requires a dedicated 3" vent. If I have a dedicated vent, doesn't the size seem excessive? I had in my memory that the vent for a dedicated water closet drain needs only be 1 1/2"

Plumber101 · 03-06-2010, 10:55 PM

Inspector is a little off. If you are venting just a water closet a 1 1/2" should be fine. But I normally run 2" just because it will be easier to snake from the roof and less 1 1/2 to carry.

Have the inspector show you in code where a 1 1/2 vent can't be used for only 1.5 dfu's

plummen · 03-07-2010, 10:58 AM

what he said! id use a 2" also for maintenance reasons but 1 1/2" would be legal in my book,just make sure it increases to 4" a foot before daylighting through the roof

Alan · 03-07-2010, 12:46 PM

2" is code minimum in Oregon.

md2lgyk · 03-09-2010, 02:21 PM

How far is the toilet from the main stack? You might not need a separate vent at all.

03-06-2010, 01:20 PM	#1
jackyyboy Newbie Join Date: Mar 2010 Posts: 1	Vent pipe size for toilet Hi, I'm installing an all new DWV system in a remodel. An inspector said that a 3" drain on a toilet requires a dedicated 3" vent. If I have a dedicated vent, doesn't the size seem excessive? I had in my memory that the vent for a dedicated water closet drain needs only be 1 1/2"

03-06-2010, 10:55 PM	#2
Plumber101 GC/Master Plumber/Mech Join Date: Feb 2009 Location: Hays, KS Posts: 1,467	Vent pipe size for toilet Inspector is a little off. If you are venting just a water closet a 1 1/2" should be fine. But I normally run 2" just because it will be easier to snake from the roof and less 1 1/2 to carry. Have the inspector show you in code where a 1 1/2 vent can't be used for only 1.5 dfu's __________________ John Wayne once said "Life is tough and it is even tougher if you are stupid" Tempstar and Trane Dealer

03-07-2010, 10:58 AM	#3
plummen retired elect/hvac/plumb Join Date: Jan 2010 Location: south east of omaha Posts: 2,391	Vent pipe size for toilet what he said! id use a 2" also for maintenance reasons but 1 1/2" would be legal in my book,just make sure it increases to 4" a foot before daylighting through the roof

03-07-2010, 12:46 PM	#4
Alan Doing it myself Join Date: Apr 2006 Location: Crescent City, CA Posts: 3,454	Vent pipe size for toilet 2" is code minimum in Oregon. __________________ Journeyman Plumber

03-09-2010, 02:21 PM	#5
md2lgyk Member Join Date: Jan 2009 Location: WV Posts: 2,216	Vent pipe size for toilet How far is the toilet from the main stack? You might not need a separate vent at all.

Vent pipe size for toilet