Easy vent question

[santhony7]

I think. Does the whole venting thing have to happen before a fixture? If I had a toilet and a lav on one straight run of 3" pipe, could one 2" vent be run up the wall between the two? The toilet is about 4 feet from the sink in a different room so they both would be about 2 feet from the 2" vent. Thanks all!

[Randyj]

I'm sure others will disagree with me because it is not totally by code...but, if you ran that vent off of the sink branch then it would vent the toilet and the sink. Since the sink is dumping into a bigger pipe it will not be pulling on the toilet. I have had an inspector tell me that NO PART of a vent shall be horizontal.... Check out the drawings Terry has posted in some of these threads and you'll see a good general layout of plumbing with vents. In this drawing EVERY branch/fixture is individually vented.

[Randyj]

Here's Terry's picture of a plumbing system...

http://i22.photobucket.com/albums/b304/friendsncompany/dwv_b2sampleplumbingdrawing.jpg

[santhony7]

But what if the vent stack came directly out of the main 3" line and through the roof? I figured this would maybe fall into the "critical distance" I keep reading about.

[santhony7]

Thanks for the picture. My problem is that all of these example diagrams are always for 2 story houses. Things change when you have one story and a finished basement. :(

That picture does help though.

[Randyj]

I don't have a clue....but I'm interested to see what others have to say. To do it RIGHT...the p-trap would go into a tee which would have a vent pipe coming out the top which would run to the vent stack... see drawing posted above.... the ell of the vent would have to be higher than the rim of the sink...someone mentioned the number 42" which sounds reasonable. If there were no tee/vent then you would still in effect have an s-trap... the effluent from the trap would suck the water out of the trap.

[Randyj]

Here's my doctored up version for a single story...

http://i22.photobucket.com/albums/b304/friendsncompany/dwv_plumbingdrawingsinglestory.jpg

[santhony7]

I see what you are saying. The overall best rule is to have each fixture vented individually. But I know that if you have a toilet that is within 6' of your stack that you don't need another vent. So I thought the same might apply to this. The problem with running a vent over to the stack in the wall is that the toilet and the sink are off set. Here are the real plans and the real scenario is having two toilets on either side of a wall. My joists run up and down so I am trying to design a system that flows with the joists so I can keep my basement ceiling.

Thank for you input, much appreciated.

[Randyj]

At some point the drain/sewer line is going to have to drop below the joists and you are going to have to maintain a 2% (1/4" per ft) slope. The last remodel I did the plumbing on I ran the main line alongside the HVAC trunk and all branches between the joists. I was still able to put clean outs in all the appropriate places.

[hj]

The way your drawing shows the vent, it is absolutely worthless for the sink, and should be accepted for the toilet, since it would work.

[Randyj]

This mo' better ????

http://i22.photobucket.com/albums/b304/friendsncompany/00000002.jpg