Hello All,

My question is about venting for a bathtub and toilet and the overall DWV layout. Can a vent pipe move horizontally while under the flood level of the bathtub? As long as I slope everything back to the drain I am thinking it will be OK, but I am trying to decipher a code book that I think may say different. (IRC 3104.4, UPC 905.3) If this is not allowable then I could possibly get close to the vertical vent and use a couple 45's, but then the toilet venting will be difficult to tie in. Questions and attachments are listed for clarity and listed below.

Picture List
1886 - Shows the back view of the toilet (standing where new toilet will be) with 2" vent pipe going up to second floor
1887 - Shows current connection from toilet to vent pipe
DWV Layout - Shows my plan to move toilet to other side of wall, bathtub to where the toilet currently is and DWV plan.

1. Can a vent pipe move horizontally while under the flood level of the bathtub?
2. If not does this code apply for toilets also? The current vent pipe runs horizontally and attaches with a 90. I am not sure if this is original, the bathroom looks to be previously remodeled.
3. For dry venting are there any fitting restrictions like 90's wyes or sanitary tees?

Thanks for any time spent on this, I appreciate any help provided and if anyone would like to make comments on anything else that seems out of the ordinary please do.

Thanks

Hi Help:

Hey, 1st question was if could move a vent pipe horizontal below the flood level rim of the fixture... Answer is YES you can... as long as where you connect it into the vent system is at least six inches above the flood level rim of the fixture.

I do see issues with drawing as you presented.

If planned properly, you run 3" pipe to toilet, then take 2" pipe off just behind toilet fiiting/elbow and run 2" pipe to lavatory....the tub also connects into this 2" pipe. The 2" lavatory vent acts as a wet vent for the tub and toilet and as its own vent by itself.

Let us know if need more... Mark

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Quote:

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Originally Posted by massplumber2008

Hi Help:

Hey, 1st question was if could move a vent pipe horizontal below the flood level rim of the fixture...Answer is YES you can....as long as where you connect it into the vent system is at least six inches above the flood level rim of the fixture.

I do see issues with drawing as you presented.

If planned properly, you run 3" pipe to toilet, then take 2" pipe off just behind toilet fiiting/elbow and run 2" pipe to lavatory....the tub also connects into this 2" pipe. The 2" lavatory vent acts as a wet vent for the tub and toilet and as its own vent by itself.

Let us know if need more...Mark

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Mark,

I am trying to figure out what you suggested but I am a little confused. You say to run a 2" pipe to the lavatory. The lav is not connected on that side of the room and will be separated by a doorway. I only have the tub and toilet to work with, and they must share the 2" vent. I think I can avoid a went vent completely.

Either way, from your answer to my first question, it sounds like I will need to run an adjacent vent pipe up for the tub since I will be moving horizontally under the floor(and FLR), and then connect using a branch vent higher up.

Thanks for the help.

OK... no sink:

Check out how the tub in this picture is trapped and vented... you are fine on toilet and toilet vent.

The tub needs to come off the 3" vertical and needs 1.5" trap and 1.5"vent so that vent comes off the top of the 1.5" sanitary tee fitting that picks up the trap for the tub... that make sense (see pic... just ignore sink in pic and toilet for that matter... concentrate on tub)

Most 30" tubs rough in at 14-15 " from back wall to center of tub waste and overflow assembly... and about 1.5" from end wall to center of tub waste and overflow assembly. The trap inlet wants to be roughed in to match those numbers... but you need to put your center drain line measurements in place of the ones I just presented (may be the same.. ).

Let me know what you can... Mark

Quote:

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Originally Posted by massplumber2008

OK...no sink:

Check out how the tub in this picture is trapped and vented....you are fine on toilet and toilet vent.

The tub needs to come off the 3" vertical and needs 1.5" trap and 1.5"vent so that vent comes off the top of the 1.5" sanitary tee fitting that picks up the trap for the tub....that make sense (see pic...just ignore sink in pic and toilet for that matter...concentrate on tub)

Most 30" tubs rough in at 14-15 " from back wall to center of tub waste and overflow assembly...and about 1.5" from end wall to center of tub waste and overflow assembly. The trap inlet wants to be roughed in to match those numbers...but you need to put your center drain line measurements in place of the ones I just presented (may be the same...?).

Let me know what you can...Mark

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Mark,

I had been looking for a picture, even before my original post, to lead me in the correct direction. Do you happen to have or know where I could find a picture that would show two fixtures back to back like I am doing? The tub is 42" wide and the toilet will be 15"-18" away from the wall. Thanks

Hey Help request:

I will try to draw something up in the next 24 hours or so... if can wait that long I should be able to show you how I would do it.

If you don't see somethng by Wednesday morning please PM me to remind me.. ok?

Talk soon... Mark

Mark,

It's not a hurry, I'm still in the framing phase, just trying to plan ahead. I think I have a strong grasp on what to do, I am thinking it will be tight to fit the two drains, P-trap and vents so close to each other. A generic picture off the internet would probably work, I am just having trouble finding one.

Thanks

That's why we are going to plumb this up so you only use that 2" vent to vent both toilet and tub. You will see... ;) Talk soon... Mark

Quote:

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Originally Posted by massplumber2008

Hi Help:

Hey, 1st question was if could move a vent pipe horizontal below the flood level rim of the fixture...Answer is YES you can....as long as where you connect it into the vent system is at least six inches above the flood level rim of the fixture.

I do see issues with drawing as you presented.

If planned properly, you run 3" pipe to toilet, then take 2" pipe off just behind toilet fiiting/elbow and run 2" pipe to lavatory....the tub also connects into this 2" pipe. The 2" lavatory vent acts as a wet vent for the tub and toilet and as its own vent by itself.

Let us know if need more...Mark

.

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Mark,

I bought a plumbing book at Home Depot that has a lot of general information in it. Please see the attached page from the book, 123 Plumbing, what it shows I think is contradictory to what you are saying earlier. If I could connect to the existing vent system under the FLR and move horizontally than my setup would be much easier. Is what this book is showing incorrect? Thanks

Bump

Hey helprequest... Tom just let me know that he got your email and tried to upload your picture.. but would not work for him.

I am sorry... looks like I lost you way back into the older posts and emails section...

Give me until later tonight to review all information again and post an answer.

You are at top of list now... ;) Talk soon... Mark

Quote:

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Originally Posted by helprequest

Mark,

I bought a plumbing book at Home Depot that has a lot of general information in it. Please see the attached page from the book, 123 Plumbing, what it shows I think is contradictory to what you are saying earlier. If I could connect to the existing vent system under the FLR and move horizontally than my setup would be much easier. Is what this book is showing incorrect? Thanks

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Your photo shows a typical wet vented bathroom group.

However, your original question described a scenario where you are providing a vent specific to an individual fixture, a toilet.

The IPC makes provisions for using both methods -- Either wet venting a group or individual vents for each fixture.

However, if you are going to individually vent the toilet and tie it into an existing common vent, then you must be at least six inches above the flood rim of the highest fixture served by the common vent before tying the toilet vent into the common vent.

Mark, Thanks, I wasn't sure if you were still around. I know this is free help and you are probably busy so I hate to nag.

Growler, the toilet is connected to the 2" common vent, anything else would be branching into it, I'm guessing your answer works vice versa though. After looking at my setup I have come to the conclusion that there isn't a way to tie the tub and toilet together under the floor without making the tub use a wet vent (about a foot of wet vent). For some reson I was thinking wet venting a toilet drain wasn't good, but can't find anything negative literature about it. Thanks

Hey HR:

Yeah... I'm still here... ;) And always glad to help... when I don't misplace you!

Hey... I seem to remember that you did not want to run individual vent for toilet AND for tub... so we were trying to get you up and running using only that 2" vent in pictures.

I think we can do it (see attachment)...but may need to chop into the concrete a bit. The 3" x 2" wye needs to come off at centerline.

The question is whether running an individual vent for the tub outweighs chopping concrete to make this happen..?

Look at pic... let me know what you think... Mark

Quote:

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Originally Posted by massplumber2008

Hey HR:

Yeah...I'm still here...;) And always glad to help...when I don't misplace you!!

Hey...I seem to remember that you did not want to run individual vent for toilet AND for tub...so we were trying to get you up and running using only that 2" vent in pictures.

I think we can do it (see attachment)...but may need to chop into the concrete a bit. The 3" x 2" wye needs to come off at centerline.

The question is whether running an individual vent for the tub outweighs chopping concrete to make this happen...???

Look at pic....let me know what you think...Mark

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Mark,

Yeah, chopping into the concrete would not be fun. Check out the picture, this is what I was thinking. I don't know if the combo would be OK to use here, I was thinking the force of the flushing toilet would cause problems. Or using just a plain long sweep might work and waiting until the pipe turns vertical and add a wye to connect the tub vent into.

If this doesn't make sense then no problems, I will just run a branch vent since that seems to be OK and would probably be safer. I thought I could avoid a vet went, but I don't have enough room. Thanks

Hi HR:

I super appreciate that you are trying so hard to get this right!

Your pictire shows that combo long sweep and you ask, "Can tub vent be tied in here??"

Sorry... no, tub vent cannot tie in here. I think we're hung up about venting still. It is why plumbers study for years!

I am sorry this is so difficult... Clearly there is no issue venting the toilet. Clearly! So, if could run tub waste off 3" vertical using a 3"x 2" wye, then run tub waste and an individual 1.5" tub vent, you would be finished.

If can't do that... I showed you how to WET VENT the tub in my post.. involves chipping concrete out, but reduces the need for that individual vent to the tub.

I see what you are trying to do... and I see that you keep getting hung up on the tub vent connecting into the pipe under the floor... and it does connect under the floor... BUT IT NEEDS TO CONNECT UNDER FLOOR IN A WAY THAT THE VENT CONNECTS INTO DRAIN SO THAT IT IS ABOVE THE WEIR OF THE PTRAP... then it can go vertical.

The picture I presented in my last post does that (2"x 1.5" sanitary tee, picks up tub trap, 2" vent continues vertical out of the sanitary tee... ABOVE TRAP WEIR). (LIKE 2nd PIC. BELOW)

If you run an individual vent for the tub you will still need to run the vent off the drain line so it is ROLLED ABOVE THE CENTERLINE OF THE TUB DRAIN... again above the trap.(LIKE 1st PIC. BELOW)

Check out these two pictures I attached... both show illegal vents (most areas), but both also show what I am talking about. 1st pic. Shows you how vent is above centerline of trap, 2nd pic. Shows how vent is also above centerline of trap... this make sense?

All traps need vent to come off above that trap centerline like these pics.

Hey, that's what I have for you... let me know what you think. Either individually vent that tub,or start chopping... ;) Mark

Mark,

Thanks for the explanation, I understand now what the restrictions are. Explain the same thing a few different ways and I'll eventually get it, hehe. Looks like I will be running a separate vent for the tub. Thanks again for the help.

HR... this is not easy concept... you did great!

And, I still want you to give this a day or two... hoping Tom or Iamgrowler (or others.. you know who you are.. ;) ) get a chance to review this in complete... maybe they have another idea.

I mentioned that air admittance vents (AAVs) are mostly illegal... wondering if we discussed these..?

I would check with local plumbing inspector, describe situation, and see if he will approve a mechanical air admittance valve WITH ACCESS PANEL for future access.

If he will... would allow you to run vent pretty much as pictures present in my last post (just have to be accessible... so when I use one... RARELY... I run up above tub, near the shower valve so when install access panel I can access both AAV and shower valve).

Let me know last thoughts on this. Still trying to offer better solution to your issue.

Check with local inspector... even if only asking "hypothetical" question... ;)

Good night... Mark