Fixture Vent Sizing - Plumbing - DIY Home Improvement | DIYChatroom

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Plumbing


Thread Tools Display Modes
Old 11-26-2011, 12:12 PM   #1
Join Date: Nov 2011
Posts: 5
Rewards Points: 10

Fixture vent sizing

I have a 1.5" pvc pipe that vents my dishwasher and kitchen sink that has to be rerouted. Due to size restrains, using a 1" pipe for the last 3 feet before it penetrates the roof would make my life much easier. Code issues? I want to do this right, not just easy. Thanks


123ozzie is offline   Reply With Quote
Old 11-26-2011, 01:44 PM   #2
ddawg16's Avatar
Join Date: Aug 2011
Location: S. California
Posts: 10,388
Rewards Points: 8,066
Blog Entries: 2

According to the regs in my area (which typically follows national standards), 1.5" is the minimum for any vent.


Even if you are on the right track, you will still get run over if you just sit there.

My 2-Story Addition Build in Progress Link ... My Garage Build Link and My Jeep Build Link
ddawg16 is online now   Reply With Quote
Old 11-26-2011, 01:52 PM   #3
TheEplumber's Avatar
Join Date: Jul 2010
Location: North Idaho
Posts: 9,504
Rewards Points: 98

Kitchen sink requires 1.5" vent and you can not decrease a vent pipe size.
TheEplumber is online now   Reply With Quote
Old 11-26-2011, 03:20 PM   #4
Join Date: Nov 2011
Posts: 5
Rewards Points: 10

Thats kinda what i thought, thanks for responding
123ozzie is offline   Reply With Quote
Old 11-26-2011, 04:12 PM   #5
Join Date: Oct 2011
Location: PA
Posts: 5,918
Rewards Points: 582

you can't reduce vent stay at 1.5 all the way..
ben's plumbing is offline   Reply With Quote
Old 11-28-2011, 08:00 AM   #6
Join Date: Jan 2009
Location: WV
Posts: 3,471
Rewards Points: 3,130

If legal where you live, just forget the vent line and install an air admittance valve in the sink cabinet instead. That's what I did when I built my house.
md2lgyk is offline   Reply With Quote
Old 03-18-2012, 11:04 PM   #7
Join Date: Mar 2012
Location: Toronto, Ontario, Canada
Posts: 7
Rewards Points: 10

similar situation for me

Thought AAV's were not code in most places for dishwashers, due to the possible high flow rates. (however this seems bogus to me, with a 1 to 1 1/4" sink drain, a full (8-10" deep min 14x12") sink of water causes massive suction during drainage. How this can be less flow than a 3/4 drainline from a DW is beyond me. Maybe there's another reason?)


mathx is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Basement branch vent connecting below flood rim of main level fixture benjamincall Plumbing 1 07-13-2010 04:44 PM
Shingling over ridge vent -details needed jogr Roofing/Siding 4 11-06-2009 05:47 PM
Low-Slope Ventilation - Cobra Fascia Vent and Cor-a-Vent Roof-2-Wall vent atulc Roofing/Siding 7 08-22-2008 10:40 PM
Bathroom Vent Not Vented to Outside / Would need to vent through flat roof House_Amuck HVAC 5 03-30-2007 09:57 AM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1