Adding a Bathroom to a bungalow attic - Toilet Venting Question

Awpurcell10

Awpurcell10

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LavVenting.jpgToiletVenting.jpgI am adding a large bathroom in an attic with double lavs, a shower and toilet. Based on my floorplan, I am venting everything individually because I do not want to drill through the floor joists. Since my lavs and shower will have a plumbing wall, I am going straight through the roof for venting, which is intuitive and easy. However, my toilet is on the other side of the room and I would like to tap into to my original 4" dry vent for my first floor fixtures, in order to vent the toilet. I have attached the picture. I need to get the low-heel 1-1/2" connection tapped into my 4" vent. Are there any restrictions or general rules that dictate how I do this? For instance, can I only tap into the 4" at a certain height? Or can I only have a limited number of turns? Ideally, I would like to run the 1-1/2" in the sub-floor (with a slight upward slope) around the 4" drain and then connect on the backside (rightside in the photo). I want to build a short wall for astetics on the left side of the 4" dry vent. Also, can I use a 3" street 90 degree bend as my toilet connection? Or do I have to use a 4" to 3" closet bend? (In the picture I have a 3" street 90.
 
ToiletVentingV2.jpgOkay, I will check into the 2" VS. 1-1/2" toilet drain. If I need to use a 2", is there a similar option for the 3" pipe using a low-heel connection like I have already purchased, assuming I was going to use 1-1/2". Other than not accurately drawing the reverse pitch, are the markings on my picture an accurate visual description of what I can do?
 
You would be better off venting the toilet lower using a 3x2 wye fitting. That way you can continue up with the vent with less bends.

The lav needs a 2" where the two combine. Also you will need to either vent each one, or use something like a fixture cross you are only venting once.

The fitting for the 4" needs to be a shielded coupling, not a rubber fernco. A rubber fernco can only be used in the dirt (below grade).

Plumber2011, I'm glad you added the tool belt; it was a bit risqué before.
 
So is my venting sufficient for the double lavs? Everything is run in 2" in that pluming wall.

Here are a few changes I will make and other thoughts:

1) Change to a 4" shielded coupling on the dry vent
2) Replace the 2"elbow currently facing upwards with a 90 degree 2" street elbow turning horizontal, then reduce down to 1-1/2"
3) I checked with a local plumber, and he said I could use 1-1/2" vent for the toilet, since it was only venting that fixture and it is a dry vent.
4) Can I put my 2" vent Tee under the 2" tee catching the lav? (As pictured it is above and I think it may be too high at 26"). Is there a rule of thumb for the height that the drain should come out of the wall?
5)
 
Can I keep my existing tee on the right side where it is now, or do I need to move my drain opening to the left, so it not at the vent tee? From Terry's message, it almost seemed like I needed to relocate that drain, so the vent would count for both sinks. Is that accurate? If I can keep the height of the holes I have already bored out, and keep the location of the drain/vent tee on the right side, can I move the drain tee beneath the other tee so my drain would be lower? Also, will is there any code around the height of the drains? I would prefer not to have to rip those studs out and replace if I do not have to (assuming my vanity height/sink depth will be compatible their existing locations. Let me know. Thanks for the help guys!
 
Can't tell from the discussion......you aren't planning to send your attic toilet waste down the vent from the first floor are you?
 
Because your lav basins are draining into the vertical pipe at different elevations, (as in the original picture) it is considered a wet vent. To meet WI code for a vertical wet vent, the drain between the two fixtures must increase one pipe size AND be not less than 2".

If your right tee is 2x2x1.5, you are good, as long as you turn the bend on the right basin so it is coming straight out of the wall (without the vertical drop).


Edit -- I have the same question as Jim about how & where your drain connections are being made.
 
Last edited:
No, I am adding a secondary 3" stack, which I will tie into the main stack, beneath where the 1st floor lav, tub and toilet tie in.
 
Yes, it is a 2" x 2" x 2" (even have a 2" vent for this one, just to keep it simple). Also, I think you meant I need to turn the bend on the left side, correct? Can I swap the locations of the two tees on the rightside, in an effort to get the drain coming out of the wall lower, as I think I am too high right now (26"). I dont want to stud the wall if I do not have to...
 
The top tee must be a 1.5" arm dumping into the 2" vertical drain.

The tee 14-18" off the floor will work for a common vanity. 26" will be too high for the trap.

I would cut the studs out and install new ones.
I see plumbers doing it, but 60% is the max hole permitted in a non-bearing wall per the IBC.
 
I think you should have decided on the lavatory drain configuration BEFORE you drilled the holes. WE do not have measurements but it appears that BOTH sink drains may be too high. I would have done the entire system differently.

quote; I see plumbers doing it, but 60% is the max hole permitted in a non-bearing wall

Well that would pretty much exclude a lot of horizontal in wall piping.
 
agreed, I started re-doing it last night...it is a good thing PVC/wood studs are cheap! One of my friends is helping me with this and I just think he was moving too quickly. I will post the new (and improved) picture tomorrow or Thursday.

Nothing like doing things twice..."If you dont have time do it right, when you have time to do it over again?"
 
Is this better? I made the following changes:
- changed the piping for the lavs to 1-1/2" (on the slope, still 2" going down to the basement"LavsV2.jpg
- re-studded the walls and put smaller holes in the studs
- lowered the holes
 
I, and most inspectors, would NOT approve that right hand sink being connected that way. It was CORRECT the way you originally had it. The problem was with the left hand one.
 
Really? Why not? This was actually the way it was suggested to me by a licensed plumber. Another more general question, I need to cut-out a piece of the cast iron and replace with a 4" x 3" wye and a 4" cleanout. Is there any issue with using PVC for this (per code). I hear a lot of people recommending that the CI is used to replace the CI cut-out, but there is a lack availability in this area so I would like to use PVC if I can.
 
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