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Discussion Starter #1
I bought a house new in 2004. The basement was plummed for a future bathroom. There is a 2" bath drain pipe coming out of the slab in a square tub box, a larger drain out of the slab for the toilet, and there is a drain coming down the wall from the upstairs plumming for the sink. It has a capped off "T" split to tie into. My question is, how can i tell if the tub and toilet are tied into a vent? If I tie the sink into the T split from the upstairs plumming, can i assume the sink will have proper ventilation? Am I going to have to tear up the concrete to vent the toilet and bath? It seems like the builder would have done this before pouring the concrete however I cant ask them because they went out of business of course!
 

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and there is a drain coming down the wall from the upstairs plumming for the sink. It has a capped off "T" split to tie into. My question is, how can i tell if the tub and toilet are tied into a vent
If there are any fixtures on upper floors draining into this " drain coming down the wall " then you cannot vent the basment bathroom group by tieing into this drain. Unless of course you were to tie in above the flood level of the highest fixture that ties into that stack.

Like in the photo below. As long as there are no fixtures draining into that stack above fitting #5, it is OK to use above fitting #5 as a vent for this group. This group below is obviously a washer and utility sink.
 

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Discussion Starter #3
That makes sense, i guess venting from that line is not an option. I dont understand why the builder wouldnt have tied these drains into a vent line. There are no other vents to tie into in the basement and I am going to have to break up the concrete to get to the toilet and tub drain...can i just make a new vent and just vent it right outside of the basement wall?
 

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Discussion Starter #5
It looks like it comes from the kitchen so I assume the sink and the dishwasher...could I just use air admittence valves, not taking into consideration my local code
 

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Discussion Starter #6
Upon further inspection...i beleive the 2" pipe coming down from upstairs is a drain pipe, all other drains from upstairs are draining into a larger drain pipe elsewhere in the basement. Is it logical to think the builder tied the toilet and tub into this vent beneath the slab?
 

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Are you sure the 2 going up isnt just a vent? Why would they rough it in without a vent. Have you run the water in the sink or scoped out the 2?
 

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What size is the the pipe from above?
Uncap the tee and run water upstairs. If you don't see any water coming down the pipe then it may be the vent for your basement fixtures- it may be revented upstairs already.
A picture of your layout would help.
 

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Discussion Starter #9
Uncapped, no water! It is a 1.5", at the T it then is a 2 inch that goes into the slab....there is also a junction near the slab with a cap...is that to tie a sink drain into? I attched a pic! Thanks for your help!

ForumRunner_20130211_150142.jpg
 

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The capped outlet is your bathroom sink. The tee at the base is a clean out.
If this was in my area, I'd be looking for another vent pipe in the floor.
A toilet should be vented with 2". What you pictured is 1.5"
 

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Discussion Starter #11
Hmm...i looked and there is no other pipe coming up...is it possible they tied the toilet and tub into the 1.5" vent?
 

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Hmm...i looked and there is no other pipe coming up...is it possible they tied the toilet and tub into the 1.5" vent?
yes, just about anything is possible :)
Some areas have different ways to vent toilets.
Have you dug into the floor box to see whats down there?
 

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Discussion Starter #13
Not yet...will do though! This forum is great....what is the purpose for that tub box anyways? Is it just easier to move the tub drain around if needed??
 

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Discussion Starter #16
Yes hammer. As you can see I am a noob. Just by looking i thought it was drain, but after some info from other posters I realized it was a vent.
 
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