I had my contractors plumber rough in a shower/toilet/vanity in my basement before the floor was poured and Im looking at finishing it off. I have done some plumbing projects before but have never seen or dealt with a basement project. I have 3 pvc pipes, 1 for the toilet, 1 for the sink and 1 for the shower.
Question #1 - At the shower drain there is a black plastic cover around the pipe flush with the concrete. I have seen these many times in other houses but never paid any attention to them. When this is roughed in, is the P trap usually installed below this box or will I need to open it up and install a trap?

Question #2 - The vanity sink drain is just stubbed up from the floor coming up next to the wall. Do I need to vent this somehow and if so, are there any links on the internet that anyone can refer me to on how to do this? I've done some searches and can't find anything useful so far.

Im sure I'll have some other questions but that will get me started. Thanks

Hey Ski,

"Question #1 - At the shower drain there is a black plastic cover around the pipe flush with the concrete. I have seen these many times in other houses but never paid any attention to them. When this is roughed in, is the P trap usually installed below this box or will I need to open it up and install a trap

If you can a vertical shower raiser then there's a trap under it. The plastic cover is a test cap that to use to seal off the drainage when we flll the pipes for inspection.

Question #2 - The vanity sink drain is just stubbed up from the floor coming up next to the wall. Do I need to vent this somehow and if so, are there any links on the internet that anyone can refer me to on how to do this? I've done some searches and can't find anything useful so far.

Venting answers are all over the posts in here. You run the vanity line up 18" from the floor to the center of a 2X2X1 1/2" drainage tee, The center 1 1/2" will stub out of the wall to pick up the vanity. The vent will run to the roof or revent back in the attic from the top of the 2X2X1 1/2" drainage tee.

Good luck, Tom

Thanks Speedball. I haven't done any searches on venting yet but I am stuck with not being able to vent to the attic or roof. However, I have a bump out on the back of the house for a ventless gas fireplace in my living room that would be right above the basement bath. I can run the vent line out the floor joists below the bump out and pop down the vinyl underneath the bump out but do you know of a way to terminate the pipe as it would have to be pointing down towards the ground as it comes out of the bump out? I would have about 3 feet to the ground but I want to make sure there's someway to keep critters or birds or anything from getting in the pipe and will the vent pipe work that way pointing towards the ground instead of pointing up? I took some pics and Ill try to post them soon because the guys that installed my water softener tied into the vanity drain to drain the softener and installed a dome type cap on the top of their pipe that has a couple of vent holes with a little knob on the top but its in the basement. Not sure if that's even good to have down there.

One other thing, I had the plumbers stub another drain line towards the middle of the basement for a kitchen sink and I also tapped the condensation drain from my central AC into it as well. The pipe comes up underneath the stairs to the 1st floor and its freely venting in that closet although its reduced from 2" to 3/4" at the top for the condensation fitting. Not sure what to do with this one either. Thanks again.

Hi Ski,

If you're having a problem figuring out how to vent why not install a AAV,(Air Admittance Vent) "cheater vent",(see image) on top of the lavatory tee? If you need more information on AAV's click on back.

" I had the plumbers stub another drain line towards the middle of the basement for a kitchen sink and I also tapped the condensation drain from my central AC into it as well. The pipe comes up underneath the stairs to the 1st floor and its freely venting in that closet although its reduced from 2" to 3/4" at the top for the condensation fitting."

You have a 2" AC condensate line?? Why?? The normal size for that drain is 3/4". I hope you trapped the condensate line because if toy didn't then you will have left a direct opening for sewer gas to enter your home.

"The pipe comes up underneath the stairs to the 1st floor and its freely venting in that closet"
Are you saying that you've terminated the vent in your closet? If so that's another open line from the sewer into your home.
Waiting on your reply, Tom

Speedball,
Thanks for the reply. I think the AAV you mentioned is what the water softener guys installed that I mentioned earlier. Ill look at using one of those for the vanity line. Quesiton though, I did some searches and found a 1 1/2" trap designed with an AAV 4" high - inline on the trap for under the sink installations, OR would it be better to run the 2" vent through my top wall plate and put the AAV in the floor joist?

As for the condensation line, the 2" stub will be used for a kitchen sink drain (wash tub right now) but above the "T" for the sink, I used a reducer and put a 3/4" T for the condensation line to the AC unit. It does have a trap in the 3/4" line, as does the pipe that goes to the sink-wash tub. I suppose I could just use the same AAV valve for that - I'd just have to alter what I have connected right now so I can put the AAV valve on top and reduce to the 3/4" pipe off another 2" T that would be above the 2" T for the sink.

Ultimately I guess the AAV is the answer to both of my questions. Thanks a lot !

Hey Ski,

Let's keep the AAV where it can be checked and serviced, In the cabinet.
Regards, Tom

Speedball,
That's the one I found while searching. The only reason I mentioned putting the AAV/Studor up in the floor joist is because Im just planning on putting a dropped ceiling so Ill always have access above. Didn't know if it was wiser or worked any better that way instead of beneath the sink. Thanks for the help though.