Vent Sizing - Plumbing - DIY Home Improvement | DIYChatroom


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

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 04-17-2011, 08:06 PM   #1
Newbie
 
Join Date: Apr 2011
Location: Magnolia, Tx
Posts: 3
Rewards Points: 10
Default

Vent sizing


I am completing an upstairs addition in Houston, Texas, that includes a toilet, shower, sink, and a bar sink. The drain lines were previously installed. It consists of a 3" stack to the 2nd floor. There is then a horizontal 3" line that has the toilet, then the sink, and then the bar sink. A 1-1/2" line connects the shower to the fitting at the junction of the 3" horizontal and vertical line. The shower trap is 2' from the stack. The toilet flange is 5' from the stack. The sink is 8' from the stack. The bar sink is 15' from the stack.

There is an existing 1-1/2" vent thru the roof for a half bath (toilet & sink) on the first floor directly below this bathroom. It is at the extreme end away from the septic system of the existing drain system on the first floor.

When I continue the stack up to the roof, are the toilet & shower close enough that they don't require an additional vent line? I plan on connecting the two 1-1/2" sink vents to that stack also.

If I decided to use the existing location of the vent thru the roof for the new stack vent and tie that old 1-1/2" vent into the stack vent in the attic, what is the smallest size I can make the stack vent? Can it be 1-1/2" since the drain on the first floor at that location is probably still 3" and the vent would be half the drain size?

Advertisement

pment is offline   Reply With Quote
Old 04-17-2011, 10:54 PM   #2
Plumber/Contractor
 
TheEplumber's Avatar
 
Join Date: Jul 2010
Location: North Idaho
Posts: 7,291
Rewards Points: 2,654
Default

Vent sizing


How about a drawing? I'm a little confused

Advertisement

TheEplumber is offline   Reply With Quote
Old 04-18-2011, 01:57 AM   #3
Newbie
 
Join Date: Apr 2011
Location: Magnolia, Tx
Posts: 3
Rewards Points: 10
Default

Vent sizing


The red pipes in the attached picture are what I need to add. I want to find out if I can use all 1-1/2" for the vents or do some need to be 2". Using 1-1/2" means I don't have to get on the 14/12 pitch roof.
Attached Thumbnails
Vent sizing-drains.jpg  

Last edited by pment; 04-18-2011 at 02:01 AM.
pment is offline   Reply With Quote
Old 04-18-2011, 08:48 AM   #4
Plumb or Die!
 
Join Date: Oct 2010
Location: BC, Canada
Posts: 321
Rewards Points: 250
Default

Vent sizing


My Codebook's in the truck, and it's Canadian anyways, but it'll definitely work. You seem to have a pretty good handle on what you're doing. Be sure at the top of the stack by the shower, to extend the vent height to min. 42" before you run it horizontal.
plumber666 is offline   Reply With Quote
Old 04-18-2011, 10:51 PM   #5
Newbie
 
Join Date: Apr 2011
Location: Magnolia, Tx
Posts: 3
Rewards Points: 10
Default

Vent sizing


Can the 3 horizontal lines shown in red be truely horizontal or do they need to have any slope? I now know to move the lower of the 3 lines up to 42" above the floor.
pment is offline   Reply With Quote
Old 04-19-2011, 08:21 AM   #6
Plumb or Die!
 
Join Date: Oct 2010
Location: BC, Canada
Posts: 321
Rewards Points: 250
Default

Vent sizing


Quote:
Originally Posted by pment View Post
Can the 3 horizontal lines shown in red be truely horizontal or do they need to have any slope? I now know to move the lower of the 3 lines up to 42" above the floor.
A vent should have a small amount of grade so moisture, condensation will drain back towards the drainage pipes. Depending on where you live and what code you follow, this amount of grade varies greatly. A 1/16th or 1/8th inch per foot is plenty in my books.

Advertisement

plumber666 is offline   Reply With Quote
Reply


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
vent sizing kibblesret Plumbing 0 01-23-2011 12:29 PM
Drain stack vent sizing JakAHearts Roofing/Siding 1 07-23-2010 05:44 PM
Shingling over ridge vent -details needed jogr Roofing/Siding 4 11-06-2009 06:47 PM
Soffit Vent Sizing - Really Hot Attic dmo069 Roofing/Siding 7 12-04-2008 10:33 PM




Top of Page | View New Posts