# Grades of Vents



## Abdul Hakeem (Feb 16, 2010)

Can someone please tell me the grade for 2 inch and less PVC pipe? I am on a new construction job and my foreman and other coworkers are telling me it's 1/8 inch per foot and I said it's 1/4 inch per foot minimum per code. Who's correct?


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## Optimus Primer (May 20, 2009)

Abdul Hakeem said:


> Can someone please tell me the grade for 2 inch and less PVC pipe? I am on a new construction job and my foreman and other coworkers are telling me it's 1/8 inch per foot and I said it's 1/4 inch per foot minimum per code. Who's correct?


 
whats the code book say?


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## TheMaster (Jun 12, 2009)

YOu are correct....what kinda boss do you have anyway? They are lucky to have you around or things would get screwed up.


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## RW Plumbing (Aug 16, 2010)

My code says vents have to be able to drain themselves and thats all it says. It could be 1/32 per foot as long as it is to drain, and there isn't any place the vent line is trapped.


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## RealLivePlumber (Jun 22, 2008)

It is below the flood level, and if it backs up, it might clog. Better revent the vent, and run it steep


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## RW Plumbing (Aug 16, 2010)

Any _drain_ 2" or smaller has to be 1/4 in per foot minimum pitch and larger than 2" is 1/8" That is above ground. Sanitary and storm bldg drain and sewer can be as little as 1/16th per foot.


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## Ron (Jun 12, 2008)

We can run ours flat if so desired here.


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## ILPlumber (Jun 17, 2008)

Just have to be graded to drain. The above is correct for a drain.

I grade my vent work at A+


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## ILPlumber (Jun 17, 2008)

BTW, I was a big fan of yours when you played for the Lakers.


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## LEAD INGOT (Jul 15, 2009)

Matt said:


> Just have to be graded to drain. The above is correct for a drain.
> 
> I grade my vent work at A+


 I'd give my "V" an A-, but my "DW" kicks ass.


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## AKdaplumba (Jan 12, 2010)

the cdn code book says nothing about grade for vents, but the inspector wants 1/4 per foot. And they will fail you for it.


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## M5Plumb (Oct 2, 2008)

two rules, 1/4" p/ft and payday is Friday.


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## Plumberologist (Aug 21, 2010)

well i found out today any vent not tied into a wye is not a vent??? effn inspectors are stupid. even with 1/4 per foot he calls it a flat vent says it has no washout so backups can clog it


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## 3/4 MIP (Dec 1, 2009)

Illinois Plumbing code states 1/8" per foot toward fixtures. States they must be "installed to drain back to waste"

Bottom line, IMO, if your vents are graded any old way or flat your work is going to look like crap.

I drill studs at 42", 42 1/8", 42 1/4"....... Sets the grade nice.

Shannon
2 Code Plumbing, LLC


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## RealLivePlumber (Jun 22, 2008)

3/4 MIP said:


> Illinois Plumbing code states 1/8" per foot toward fixtures. States they must be "installed to drain back to waste"
> 
> Bottom line, IMO, if your vents are graded any old way or flat your work is going to look like crap.
> 
> ...


You must use a super deep seal trap to pick up a kitchen sink:laughing:


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## Pipe Rat (Apr 5, 2009)

3/4 MIP said:


> Illinois Plumbing code states 1/8" per foot toward fixtures. States they must be "installed to drain back to waste"
> 
> Bottom line, IMO, if your vents are graded any old way or flat your work is going to look like crap.
> 
> ...


Sorry to inform you *Mr 2 Code. *Your vents are not to code.:no: On standard 16" stud spacing your vents only have 3/32" per foot of fall. A little shy of the required 1/8" per foot. I mean if your gonna correct people and all. :whistling2: Just sayin'


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## GREENPLUM (Jul 27, 2008)

you call it a vent, i call it a drain for mother nature,

the vents should have fall, 

above the minimum 

sometimes


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## 3/4 MIP (Dec 1, 2009)

Give me a break. I'm just saying, if your vents are flat, zero pitch, I feel the spirit of the code says your wrong. If they're flying, your wrong and your work is going to look like crap. Give them essentially the same pitch / grade in the opposite direction and I assure you the inspector will be pleased.

BTW, I get alot folks that think the name i chose is pretty cool. And yes, it does put a little stress on me to do the right thing.. Unfortunately, I don't have the all the answers, that why I come here for pearls.

Shannon


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## Ron (Jun 12, 2008)

I'm so glad I use the UPC code cause the Illinois Plumbing Code (IPC) Stinks.


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## Pipe Rat (Apr 5, 2009)

Just ribbin' ya Shannon  And I do like the name.
Just thought it was funny

(picture authoritave voice here)

"The code says 1/8" per foot"
"or your work will look like crap"(taken outta context he he)
"I run mine a little less though"
signed
2 code plumbing

Again just kidding with ya Shannon :jester:


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## Optimus Primer (May 20, 2009)

Piperat said:


> Sorry to inform you *Mr 2 Code. *Your vents are not to code.:no: On standard 16" stud spacing your vents only have 3/32" per foot of fall. A little shy of the required 1/8" per foot. I mean if your gonna correct people and all. :whistling2: Just sayin'


 
when im running through studs and they're at 16", I drill my holes at 3/8 of an inch. works perfect.


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## eddiecalder (Jul 15, 2008)

This could help people that suck at drilling through studs with proper grade.

http://www.stabila.com/main.taf?p=1,2,4,1

There is also one for drilling vents through roofs.

http://www.stabila.com/main.taf?p=1,2,7,1


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## Tommy plumber (Feb 19, 2010)

eddiecalder said:


> This could help people that suck at drilling through studs with proper grade.
> 
> http://www.stabila.com/main.taf?p=1,2,4,1
> 
> ...


 
When I was doing layout for a commercial job with high ceilings, then I'd use a laser. Much faster. But in residential for vertical vents, a plumb bob worked perfect. I've seen guys drop small screws from underside of roof, and when screw fell into vert. stack, then he knew where to drill roof for stack penetration.


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## Air1plumbing (Sep 28, 2010)

*vents*

Vants can run flat I alwas gave them a little slope but it is not neserely by code!


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## RealLivePlumber (Jun 22, 2008)

I don't know what code you are referring to, but you can not run a vent flat. 

"Vents shall be sloped to drain, by gravity, to the drainage system. Vents shall be free of sags, dips, and traps"


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## SlickRick (Sep 3, 2009)

Air1plumbing said:


> Vants can run flat I alwas gave them a little slope but it is not neserely by code!


 

*Introduction Requested* 
An intro is requested from all new members. In case you missed it, here is the link. http://www.plumbingzone.com/f3/.

The PZ is for Plumbing Professionals ( those engaged in the plumbing profession)

Post an intro and tell our members where you are from, yrs in the trade, and your area(s) of expertise in the plumbing field.

This info helps members who are waiting to welcome you to the best plumbing site there is.

We look forward to your valuable input.
__________________


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## spudwrench (Sep 15, 2009)

Ron said:


> I'm so glad I use the UPC code cause the Illinois Plumbing Code (IPC) Stinks.


Dry vents do stink, wet vent it!


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## CEO (Apr 2, 2009)

Plumberologist said:


> effn inspectors are stupid.


 
Real nice. Do you even hold a license or just work for a contractor?


IPC 905.2 - All vent and branch vent pipes shall be so graded and connected as to drain back to the drainage pipe by gravity.


different codes different verbage.


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## Air1plumbing (Sep 28, 2010)

RealLivePlumber said:


> I don't know what code you are referring to, but you can not run a vent flat.
> 
> "Vents shall be sloped to drain, by gravity, to the drainage system. Vents shall be free of sags, dips, and traps"


 Yes you can accord Uniform Plumbing Code and I’m not talking of wet vents just regular dry vents


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## Ron (Jun 12, 2008)

Air1plumbing said:


> Yes you can accord Uniform Plumbing Code and I’m not talking of wet vents just regular dry vents


Your correct, vents can be run flat under the code we use.


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## Ron (Jun 12, 2008)

slickrick said:


> *Introduction Requested*
> An intro is requested from all new members. In case you missed it, here is the link. http://www.plumbingzone.com/f3/.
> 
> The PZ is for Plumbing Professionals ( those engaged in the plumbing profession)
> ...


Rick

He is cool he is from my area, up North, Washington/Portland Oregon. Looked up his website.

Welcome to PZ Air1plumbing


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## Air1plumbing (Sep 28, 2010)

You guys check it out I’m not talking dust!


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## Air1plumbing (Sep 28, 2010)

Ron said:


> Rick
> 
> He is cool he is from my area, up North, Washington/Portland Oregon. Looked up his website.
> 
> Welcome to PZ Air1plumbing


Thanks Ron! I just sow you posted the same code on the first page! I’m a journeyman Plumber I got a Journeyman License in 3 States and I have a business in 2 states this might answer some peoples questions!


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## Ron (Jun 12, 2008)

Air1plumbing said:


> Thanks Ron! I just sow you posted the same code on the first page! I’m a journeyman Plumber I got a Journeyman License in 3 States and I have a business in 2 states this might answer some peoples questions!



Yea everyone uses a different code, Do you find much difference in the OPSC from UPC code in Washington?


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## Air1plumbing (Sep 28, 2010)

What I like about Washington is really straight forward UPC Code, Washington state amendments are very few. Oregon it got a lot of amendments I would say the most toughest Plumbing code I ever seen I traveled quit a bet Oregon is the hardest state to get you journeymen License or do work


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## plbgbiz (Aug 27, 2010)

In Oklahoma we're on the 2009 IPC (International Plumbing Code).

 *905.2 Grade. *All vent and branch vent pipes shall be so graded and connected as to drain back to the drainage pipe by gravity.
 
Amount of grade is not specified.


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## RealLivePlumber (Jun 22, 2008)

Running them flat is just plain WRONG, I don't care what that code says. 

Condensation, and rain water, will lay in the pipe. 

Besides, you know how it is, if you let 'em lay 'em flat, pretty soon they'll be installing them with backpitch:yes:

Give an inch, they'll take a mile.


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## Tommy plumber (Feb 19, 2010)

RealLivePlumber said:


> Running them flat is just plain WRONG, I don't care what that code says.
> 
> Condensation, and rain water, will lay in the pipe.
> 
> ...


 
As we all know, just because it's in the code book, doesn't mean it's proper. Any debris in a horizontal section of vent (ie.: leaves, small animals, insects, etc.) should be washed to the base of stack so it can be carried into the bldg. drain. A flat vent line won't efficiently do that. Why do you think we pitch the fittings to the roof in a vent? So anything in the vent drains down to sanitary and doesn't cause any obstructions.


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## suzie (Sep 1, 2010)

Abdul Hakeem said:


> Can someone please tell me the grade for 2 inch and less PVC pipe? I am on a new construction job and my foreman and other coworkers are telling me it's 1/8 inch per foot and I said it's 1/4 inch per foot minimum per code. Who's correct?


 
What does your state's code book say? Plumbing code isn't universal across the U.S.


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## nhmaster3015 (Aug 5, 2008)

IPC, UPC NSPC all say this

* All vent and branch vent pipes shall be so graded and connected as to drain back to the drainage pipe by gravity*.


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## plumbpro (Mar 10, 2010)

IPC requires 1/4" min on 2" drains. Vent just require fall back to the drain


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## Ron (Jun 12, 2008)

My code says this, I'm sticking with it, yep, and your not changing it, no way.


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## Air1plumbing (Sep 28, 2010)

I can tell that everyone is from different part of US and there are different plumbing codes, but what i think here in US we got one of the Best Plumbing Code as I seen so far, travelled to Europe there plumbing is treble, I don’t even know if they have any Plumbing codes? some of the houses will have a 2 inch vent for the whole house and most of the Fixtures won’t have a vent at all! now that is bad plumbing! And we are debating on some minor codes here LOL! chears :drink:


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## Air1plumbing (Sep 28, 2010)

Ron said:


> My code says this, I'm sticking with it, yep, and you and changing it, no way.


Me personally I never seen a clogged vent! So I’m sticking with are UPC code!


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## Ron (Jun 12, 2008)

Air1plumbing said:


> Me personally I never seen a clogged vent! So I’m sticking with are UPC code!


I never seen a vent that was level in an attic that had any water in it myself, vents that have been that way for many years.


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## RealLivePlumber (Jun 22, 2008)

You have obviously never worked with cast iron or steel.


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## RealLivePlumber (Jun 22, 2008)

Air1plumbing said:


> Me personally I never seen a clogged vent! So I’m sticking with are UPC code!


see above post.


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## user4 (Jun 12, 2008)

I give this vent a B-.


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## Ron (Jun 12, 2008)

RealLivePlumber said:


> You have obviously never worked with cast iron or steel.


Meh............


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## plumber666 (Sep 19, 2010)

Killertoiletspider said:


> I give this vent a B-.


I'd giver a B if there was electrical tape where the pipes pass through the steel studs.
Up that to an A it was in the back of my old Dodge on its way to the scrap yard.
The BC plumbing code states: a vent pipe must not have any depressions where moisture can accumulate. It's the same in the National Plumbing Code, which most provincial codes are slowly incorporating so that in Canada, eventually we'll all be working out of the same book.


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## Miguel (Aug 10, 2009)

plumber666 said:


> I'd giver a B if there was electrical tape where the pipes pass through the steel studs.
> Up that to an A it was in the back of my old Dodge on its way to the scrap yard.
> The BC plumbing code states: a vent pipe must not have any depressions where moisture can accumulate. It's the same in the National Plumbing Code, which most provincial codes are slowly incorporating so that in Canada, eventually we'll all be working out of the same book.


Nah. I'd stick to the B- since, as you pointed out, there is no apparent protection from galvanic action on the DWV, but mainly since the LT isn't a continuous waste and vent as required for a wet venting fixture. The lav (or sink) and LT are merely individually vented off the same horizontal drain. FAIL.

And let's face it... the code is a minimum. If the code allows a flat vent (ours doesn't, but it doesn't specify the slope) then pitch it downward. It can't hurt and it certainly helps! We go with 1/4" per foot OR MORE.


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## plumber666 (Sep 19, 2010)

I've never liked the more is better philosophy when it comes to grade of pipes, especially vents. In the kind of work I usually do, the cieiling spaces are usually T-bar, with space at a premium. And jammed with sheet metal, cable trays, lights and whatever. If I've got to tie in 5 or 6 vents together for one VTR and there's 60' between my furthest vents, that's 15" of elevation my vents are taking up if I'm 1/4' per foot. If there's a 2' space, that's not leaving any room for anybody else. And yeah, codes establish minimums. But they're the minimums that work, if they didn't they wouldn't be in there.


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## Miguel (Aug 10, 2009)

plumber666 said:


> I've never liked the more is better philosophy when it comes to grade of pipes, especially vents. In the kind of work I usually do, the cieiling spaces are usually T-bar, with space at a premium. And jammed with sheet metal, cable trays, lights and whatever. If I've got to tie in 5 or 6 vents together for one VTR and there's 60' between my furthest vents, that's 15" of elevation my vents are taking up if I'm 1/4' per foot. If there's a 2' space, that's not leaving any room for anybody else. And yeah, codes establish minimums. But they're the minimums that work, if they didn't they wouldn't be in there.


It's interesting to hear you say that especially after the day I had today. I mean, I know what you're talking about as I've had to conjur up candy from a dogs breakfast on more than one occasion and I know exactly where you're coming from...

Yet, today I had my day interupted to investigate a 4th floor flooding at a 6 floor condo complex. (These condos are less than 5 yrs old) We haven't opened the ceilings yet but my feelings are that some changes were approved without considering the amount of fall required within a space that couldn't accomodate. And I've seen this so many times before, where the bare minimum is given to the plumbers but when the finishing guys came along they simply push any pipes, wires, ducts that are too low UP a bit. I mean, what difference can 1/2" or 3/4" make?

If everything is at the bare legal minimum then I guess it can make quite a difference. Now, this is drainage we're talking about here but venting is no different if the slightest change causes a backgrade. The situation can go unnoticed for years or show up the day the occupants arrive.

So I guess what it boils down to is... are you a professional plumber, or a professional installer? There is a difference.


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## Tommy plumber (Feb 19, 2010)

Miguel said:


> It's interesting to hear you say that especially after the day I had today. I mean, I know what you're talking about as I've had to conjur up candy from a dogs breakfast on more than one occasion and I know exactly where you're coming from...
> 
> Yet, today I had my day interupted to investigate a 4th floor flooding at a 6 floor condo complex. (These condos are less than 5 yrs old) We haven't opened the ceilings yet but my feelings are that some changes were approved without considering the amount of fall required within a space that couldn't accomodate. And I've seen this so many times before, where the bare minimum is given to the plumbers but when the finishing guys came along they simply push any pipes, wires, ducts that are too low UP a bit. I mean, what difference can 1/2" or 3/4" make?
> 
> ...


 
I'm just a pipe technician. :laughing:


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## plumbpro (Mar 10, 2010)

Miguel said:


> It's interesting to hear you say that especially after the day I had today. I mean, I know what you're talking about as I've had to conjur up candy from a dogs breakfast on more than one occasion and I know exactly where you're coming from...
> 
> Yet, today I had my day interupted to investigate a 4th floor flooding at a 6 floor condo complex. (These condos are less than 5 yrs old) We haven't opened the ceilings yet but my feelings are that some changes were approved without considering the amount of fall required within a space that couldn't accomodate. And I've seen this so many times before, where the bare minimum is given to the plumbers but when the finishing guys came along they simply push any pipes, wires, ducts that are too low UP a bit. I mean, what difference can 1/2" or 3/4" make?
> 
> ...


Agreed, when installed at the bare minimum there are too many variables that can change the pitch for it to be a good install. Typically architects and GC don't take this into acount and don't care about 5 yrs down the road when it really makes a difference


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## plumbpro (Mar 10, 2010)

plumber666 said:


> I've never liked the more is better philosophy when it comes to grade of pipes, especially vents. In the kind of work I usually do, the cieiling spaces are usually T-bar, with space at a premium. And jammed with sheet metal, cable trays, lights and whatever. If I've got to tie in 5 or 6 vents together for one VTR and there's 60' between my furthest vents, that's 15" of elevation my vents are taking up if I'm 1/4' per foot. If there's a 2' space, that's not leaving any room for anybody else. And yeah, codes establish minimums. But they're the minimums that work, if they didn't they wouldn't be in there.


On the other hand, I have never seen the more is better philosophy hurt on venting. Soil lines are a different story, yet more fall is better than being back pitched in this situation.


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## Tommy plumber (Feb 19, 2010)

Which codes allow combination waste and vents?


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## Ron (Jun 12, 2008)

Tommy plumber said:


> Which codes allow combination waste and vents?


UPC 910.0 and Appendix B permits the use of combination waste and vents.


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## Tommy plumber (Feb 19, 2010)

I come across old cobmbination waste and vent stacks on re-models I do on some high-rise condos. I think some codes now prohibit them, but I'm not sure.


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## plumbpro (Mar 10, 2010)

Tommy plumber said:


> I come across old cobmbination waste and vent stacks on re-models I do on some high-rise condos. I think some codes now prohibit them, but I'm not sure.


IPC allows them for kitchens and lavs as a 3"


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## Tommy plumber (Feb 19, 2010)

I know they had limited use, ie: no urinals, no W/C's, vert. pipe had to be oversized, etc. I've read that they can blow trap seals out as the slug of waste water reaches terminal velocity due to pressure changes behind and in front of falling slug of water. So that's why I was wondered if they were still permitted.

My old 1994 SBC code book (which FL used back then) permitted them.


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## Epox (Sep 19, 2010)

I snap a chalk line or use a 2x4 etc @ 1/4" when marking the studs. perfect every time. Yet to have my first inspector complaint. But also to the newer fellers, along with the grade requirements, is the maximum lengths that are different for every size of dwv piping. Have to watch that. :thumbsup:


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## Lifer (Nov 23, 2010)

*Vents 1/4 " grade or lay them flat ....*

Well this has come up a few times in my carrier . I plumbed under a plumbing inspector for 7 years and vented close to 500 homes running all of my venting in the attic flat on the top of the trusses and never failed a house for venting issues .. As long as there are no depressions for water to collect . When i got my ticket i was on the 95 code book and now some of the guys at work are saying that vents in the attic have to be run with grade. According to the new code...

whats you opinion . anyone find this in the code book , I can not . 
2005 Canadian Code book


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## Ron (Jun 12, 2008)

Not using that code, but here they can be flat, never was an issue, never will be an issue, they work just the same as if they had grade. Other say they need grade, it does not make any difference period. All codes should be like our code.


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## Pal (Jun 12, 2010)

IF the vents are flat in a cold climate any water as little as it may be may ice up.


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## DownHill (Oct 15, 2010)

Ron said:


> Not using that code, but here they can be flat, never was an issue, never will be an issue, they work just the same as if they had grade. Other say they need grade, it does not make any difference period. *All codes should be like our code.*


Don't know if that's true. But I will say....ONE CODE! :furious:


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## greenscoutII (Aug 27, 2008)

DownHill said:


> Don't know if that's true. But I will say....ONE CODE! :furious:


I have to say I agree. I don't see why it wouldn't be to every one's benefit if there was a universal code which could be amended locally for different climates, etc.

As far as vents being laid flat or with fall on em', it doesn't make a lick of difference in performance.

Me personally, I'll run vents flat across an attic perpendicular to the trusses. Saves a lot of installing blocking.

If the local code requires vents to have some fall on them, I can do that too. It's just a little irritating that due to code variations, what works just fine in one location magically stops doing so just a few miles away...:whistling2:


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## Plumbworker (Oct 23, 2008)

my code states vents should be level or graded as to drain back to the fixture they serve


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## 3Peasdrain (Feb 5, 2010)

*venting*

yes code says able to drain back to fixture.The thing we forget is thats why we vent out the roof with 3inch pipe and bring that 4 inch into the attic at least 2 feet That helps with freezing of the vent lines


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## Lifer (Nov 23, 2010)

3Peasdrain said:


> yes code says able to drain back to fixture.The thing we forget is thats why we vent out the roof with 3inch pipe and bring that 4 inch into the attic at least 2 feet That helps with freezing of the vent lines


 I agree with the upsizing of a vent when penetrating a roof ( the reason we do that is to help reduce the risk of frost closure of the vent due to hoar frost ) but that does not mean we must grade our vents. If they lay flat on the trusses the will drain to damn near empty and allow water to drain to the nearest pipe going down......


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## Tommy plumber (Feb 19, 2010)

This topic was discussed at length in a recent thread. My code states vents are to be graded so as to drain any water, debris, etc. back to the sanitary system. With flat horizontal vents any debris (insects, leaves, twigs, etc) will not efficiently wash into the sanitary. Will flat vents work? Yes of course, just like a 1/2" vent stack will vent a fixture, but there is a better way.


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## Epox (Sep 19, 2010)

UPC here, doesn't matter what I think, the code says must have grade, I do it. Isn't that hard to do.


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## Ron (Jun 12, 2008)

mpsllc said:


> UPC here, doesn't matter what I think, the code says must have grade, I do it. Isn't that hard to do.


Yep you must use the code you follow, I use the UPC and grade not needed.


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## Ron (Jun 12, 2008)

Thread Merge


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## Lifer (Nov 23, 2010)

Wow .. there really was a long thread on this topic ... sorry i did not do my homework before i posted .. but thx for merging .

I realize in alot of different places it is stated that vents need to be graded , If i were in that place i would .. But i'm not .. So NO as far as i am conncerned support every 16 - 24 inches gained buy laying them flat on the trusses ( i'm a residential guy ) far outweighs the benefits of grading them and suporting them every 4' ( as Canada Plumbing code states ) and having them sag with the heat and lack of suport ... cuz really alot of guy's think 5 or even 6 feet is good enough for support on a vent ...

very intresting thred .. alot of us feel very strongly about this topic ...


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## LEAD INGOT (Jul 15, 2009)

I'm on a similar version of UPC as Ron is. But my problem with laying them flat on the trusses is, I have had vents in the way of can lights. Seems stupid, I know but sometimes the sparkys are trying to lay out a specific pattern with can's. I support all attic venting every other truss, and stay a minimun of 12" above the truss. I also like to grade back to vent regardless of what code says, code is the minimum.


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## Epox (Sep 19, 2010)

*Maybe it's an age thing*



Ron said:


> Yep you must use the code you follow, I use the UPC and grade not needed.


905.0 All vent and branch vent pipes shall be free from drops and sags, and each such vent shall be level or shall be so graded and connected as to drip back by gravity to the drainage pipe it serves........ Yep it can be level, now I assure you if a person is shooting for "level" there will times of a 1/8th" missed drill now and again unless you and your crew wheres a cape. And maybe so. Personally I don't accept areas of negative grade. And it does say it must drain so I will stay with the code. What about PVC sagging with time? I've done more repair than new which means I learned to look forward. Why not give it some grade? Hey it's all in perspective.


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## Epox (Sep 19, 2010)

*Maybe it's an age thing*



Ron said:


> Yep you must use the code you follow, I use the UPC and grade not needed.


905.0 All vent and branch vent pipes shall be free from drops and sags, and each such vent shall be level or shall be so graded and connected as to drip back by gravity to the drainage pipe it serves........ Yep it can be level, now I assure you if a person is shooting for "level" there will times of a 1/8th" missed drill now and again unless you and your crew wheres a cape. And maybe so. Personally I don't accept areas of negative grade. And it does say it must drain so I will stay with the code. What about PVC sagging with time? Most will do code minimums. I've done more repair than new which means I learned to look forward. Why not give it some grade? Hey it's all in perspective.


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## DownHill (Oct 15, 2010)

Simple questions: Is some grade better than zero grade? Or are they 100% equal?


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## SlickRick (Sep 3, 2009)

DownHill said:


> Simple questions: Is some grade better than zero grade? Or are they 100% equal?


As long as it was installed without a running trap in the line that would seal the vent off temp. during a heavy rain. It will work just as well. But if you have grade, you know it will drain. You decide.


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## DownHill (Oct 15, 2010)

slickrick said:


> As long as it was installed without a running trap in the line that would seal the vent off temp. during a heavy rain. It will work just as well. But if you have grade, you know it will drain. You decide.


So they are 100% equal to you. No grade is equal to some grade for vent systems.


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## SlickRick (Sep 3, 2009)

DownHill said:


> So they are 100% equal to you. No grade is equal to some grade for vent systems.


They can't be equal. The grade assures that the vent system will not trap water.


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## Ron (Jun 12, 2008)

mpsllc said:


> 905.0 All vent and branch vent pipes shall be free from drops and sags, and each such vent shall be level or shall be so graded and connected as to drip back by gravity to the drainage pipe it serves........ Yep it can be level, now I assure you if a person is shooting for "level" there will times of a 1/8th" missed drill now and again unless you and your crew wheres a cape. And maybe so. Personally I don't accept areas of negative grade. And it does say it must drain so I will stay with the code. What about PVC sagging with time? Most will do code minimums. I've done more repair than new which means I learned to look forward. Why not give it some grade? Hey it's all in perspective.



Basically I will run flat in an attic, on the trusses, now in a wall I will have a slight grade in it, maybe an 1/8" per 16 on center.


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