Understanding venting for a bathroom.

[Thekid1]

Hey guys. I've been reading alot and trying to understand and learn different scenarios of venting bathrooms. I find it pretty interesting. So I came across a website that posted a customer's idea of how to pipe out a bath. Obviously it was posted as a "what not to do". Anyway, the poster explained that the wrong tees were used and that also where the vanity ties in down stream of the toilet, that it should have been a wye slightly turned up with a 45 that aims back to the vanity.

I assume there is a lot of correct ways to do this but Im curious why it was not suggested to just eliminate this vanity drain entirely and just pipe it into the stack instead, by turning left through the wall and tie into the stack with a 3"x2"x1.5" san tee and continue 3" down to the toilet? Of course leaving the vanity vent tied in above FLM. Thanks.

 

[wwhitney]

For venting under the IPC, it would suffice to use the proper fittings on the horizontal connections (LT90s and combos), and then just delete the shower vent and the WC vent (the closet flange just connects directly to a closet elbow with a 3" discharge). Then the lav drain would wet vent the WC and the shower.

Cheers, Wayne

 

[Sponsor]

 

[Jeff H Young]

And do not roll that 3x3x2 wye ( or Combi) up beyond normal grade 1/4per ft plus a little Id say the fitting itself could have 1/2 " per ft but the way I uderstand it running everything just about dead on 1/4 " per ft is best. it isnt a perfect world but its pretty specific about it not rolling up. I dont do much horrizontal wet venting and since Im out of new construction residential have seen very little of it in practice Im sure its catchin pretty heavy here too , I keep trying to get out and walk some jobsites but havent

 

[wwhitney]

And do not roll that 3x3x2 wye ( or Combi) up beyond normal grade 1/4per ft plus a little

FWIW, I would say how much you can roll a horizontal wye or combo that is involved in wet venting depends on what is coming in the branch and what is coming into the barrel.

One of those connections will have the fixture drain to be wet vented. I.e. upstream will just be a fixture trap. The other connection will have the wet vent, i.e. drainage from one or more bathroom fixtures, one of which is dry vented.

If the branch has the fixture drain, then rolling up the wye or combo adds to the fall between the fixture trap outlet and the wet vent (the barrel of the wye or combo). That total fall is limited to one trap diameter. So roll the fitting up too much, and you have a violation.

But if the barrel has the fixture drain, and the wet vent is coming in on the branch, I believe you can roll the wye or combo as much as you like.

Cheers, Wayne

 

[Thekid1]

Thank you for your help guys.

 

[Michael Young]

Hey guys. I've been reading alot and trying to understand and learn different scenarios of venting bathrooms. I find it pretty interesting. So I came across a website that posted a customer's idea of how to pipe out a bath. Obviously it was posted as a "what not to do". Anyway, the poster explained that the wrong tees were used and that also where the vanity ties in down stream of the toilet, that it should have been a wye slightly turned up with a 45 that aims back to the vanity.

I assume there is a lot of correct ways to do this but Im curious why it was not suggested to just eliminate this vanity drain entirely and just pipe it into the stack instead, by turning left through the wall and tie into the stack with a 3"x2"x1.5" san tee and continue 3" down to the toilet? Of course leaving the vanity vent tied in above FLM. Thanks.
View attachment 98540

The vent for your shower is flat and dry. Won't pass inspection. Your drawing looks like you have SANITARY TEES laying on their sides. illegal to lay sanitary tee on its side. all of your bends should be long-sweeps. If you're on a slab, increase pipe diamater to 2" minmum pipe size under slab. Nice drawing. But you have a few problems here.