Hello, I have a few questions regarding my home, which I built back in 02'. I have a bit of general experience with plumbing practices, but not enough for performing an install in the basement vs. main or upper floors.

Summary:
I had the plumbers install a rough-in for sink, toilet, and tub/shower in the basement. What I have is a 4", 3", and 2" PVC stubbed out about 6-8" out of floor (also backflow valve - which is flush).

1. 4" PVC: I know this is for the toilet, but my toilets upstairs are all plumbed with 3". Do they make a flange for 3" or 4" applications? If so, I understand. Also, I know how the flange is installed on upper floor, but how does flange mount to concrete? What is the order of installation? finish floor then cut pipe? I have read some forums where they speak of chiseling a groove around the pipe for flange to fit... or did I misunderstand? How about the bolts that the toilet mounts to... are those a part of the flange assembly or do I need to mount studs into the concrete? Is the whole goal is to have bottom of flange flush with finished floor before installing toilet?

2. 3" PVC: I know that this is for my sink, since the plumbers adapted a 3" to 2" Tee, where the top of Tee (3") has a threaded cap and the 2" end horizontally elbows out and up the wall about 18" with another Tee installed from 2" to 1-1/2" for sink drain. The top of this 2" Tee also has a Studor mini-vent (which I assume takes care of my venting issue for the sink?) Is this pipe 'good to go' as far as just hooking up the sink drain?

3. 2" PVC: I hope this pipe is for my tub/shower. I have seen other rough-ins with a sandbox cut into the concrete floor with 2" PVC stubbed out of the middle of the box with pea stone filler in the cutout. Mine is completely concreted around the pipe stub. Is this because I specified a tub/shower rather than a shower only? I'm not really sure what the cutout with pea stone is really for...anyone know?

4. Backflow Valve: What do they do and how do they work (if anyone knows where I can see a flow diagram of one of these, please let me know) Can I cover this with flooring since it's located in the middle of where I will have finished floor?

5. Venting: I'm not 100% sure of what the PVC plumbing system looks like under the concrete floor, but with the exception of the sink (already vented with Studor vent) is there plumbing to take care of the venting needed for the tub and toilet? ...because I see no more stubs coming out of the floor. I read another forum where it sounded like there was a vent pipe stubbed out of the floor. ...or do I need to add a vent to these systems somehow? If so, do plumbers have that accounted for in the system? if not, the nearest pipe I have is over 20' away and is a vertical drain pipe coming down the wall into the concrete (this is 1 of 4 drain pipes (3") in the basement) from the wash sink upstairs laundry room. Can I get a little detail on how to do this, if it is required for me to tap into other pipes for venting? ...or hopefully everything is good and no venting by me is required? ...I hope!

I know it seems like a bunch of simple stuff to most of you, but all or any help is very much appreciated. I thank you in advance!

Scott

 

Welcome to the forums!! We will probably ask as many questions as you do, but it is to clarify things, so here goes:

1. Finish your floor, cut off the pipe and glue in a flange. You can buy one that fits either a 3" inside and 4" outside, so yours will slip inside the pipe. It won't matter if the flange is sitting on top of your tile or finished floor, as toilets take that into consideration.

2. Good to go.

3. You will not get a tub shower unit in where you have a solid stub out. Take a hammer and hit the concrete around this pipe. Sometimes the hollow sand box is covered with the concrete pour. There should be a plastic box turned upside down in the box. The purpose of this square hole is to allow you to hook up the ptrap and drain for the tub. Without it, you won't be able to get your hands in it, and the ptrap must extend below grade level. Post back with the results of your hammering.

4. The backflow valve is a one way valve that lets water leave the house, but either with a flap or other means, prevents water from re-entering the house should the system flood. You can cover it up, but should it ever fail, you will need to remove the tile over it in order to repair it. Not a big deal.

5. Not being able to see what your plumbers did, I can't comment on the venting. Surely they took into account properly sized and placed venting, but with the Studor valve taking care of the sink, I have questions regarding the tub/shower. Call them back out and have them explain the venting to your satisfaction. Ask them specifically how the tub is vented.

Hope this helped. If you need further information, let us know, as there are a bunch of pros on the forum that really know their stuff.

 

Thanks for the 'welcome' and reply. I remember when the flatwork for my basement floor was completed and it was fully poured (no box frame for pouring bathtub stub), BUT, is it possible that the P-trap is already installed under the floor?

Also, I have read a few other forums here where it was explained that if the plumbing passed inspection, there should be a venting system in place (it's a city home and was finished end of '02). Some have said that the venting system is most likely built into the wall and goes up to the main through the roof. I've never seen a foundation wall with a PVC vent stack going up through the top of it when I put the floor down ;o) There are no vent PVC plumbing above the basement ceiling for about 20' in two directions. One is drain going down wall for laundry sink and washing machine draining upstairs. And the other is a drain for my bathroom tub, sink and toilet.

I know that there are two stacks coming out of the roof. If I remember correctly, one is for master bath, and the other is for 2nd bath and laundry room. Kichen has Studor vent...as well as sink stub in basement has Studor already installed.

Any tips on how I can figure out the vent issue? I called the city to see what there inspection criteria is and the inspectors never call back. As far as the plumbers go... lost the phone number after project was finished. ...I guess I'm looking for an answer that I may be able to verify myself if you have any other suggestions.

By the way, what does a stubbed basement typically look like with venting installed and ready for connection... a pipe coming out of the floor, up the wall, and up to the attic? Just curious if any diagrams or pics are out there.

Thanks again in advance!

 

It can be either way. Sometimes the venting runs up the wall and out the roof. If the stubbing was done in an offset manner, they may not run a continuous pipe up, and cap the vent, as I had described earlier, but if it is close to being in plane, the vent is continuous.
Most of the hardware and big box stores will carry an array of good "how to" plumbing books that should give adequate stub information that can shed light on what should be there.
Good luck, and post back if more info is needed.

 

You can pour water down the shower pipe; if there's a p-trap, it'll hold water (the whole point of a p-trap) which you'll be able to see with a flashlight.

BTW, 3" is pretty big pipe for a lavy drain. 1½" is usually adequate.

 

Thanks again for the replies Chandler & Steve. I was finally able to get with city plumbing inspector and I described my stubbing having sink drain equipped with studor vent and the others were just stubbed... then I asked how was the system vented for toilet and shower? He replied that the studor system should be acting as the vent for the whole system (which is a 3" pipe coming up from floor - reducing tee to a 2" horizontal - 3" vertical end of Tee is cleanout and 2" horiz is elbowed up to another reducing tee to 1-1/2" for drain and vertical 2" is for studor). So, should I assume the system is a wet vent since the studor is venting the original sink drain? Dunno, but he made it sound as if this is typically how the studor works for the city's (or state?) required venting practices. I'll check out some books at HD, Lowes or Menards. Is there any particular book out there anyone recommends that shows some illustration of basement stub (venting) systems? Please let me know.

Also thanks for the post on checking the tub Steve. I'll spill some H2O to check it out. Also, you mentioned my 3" drain being too large. It's funny because my kitchen sink has a 3" also that is reduced to 1-1/2" with studor vent... which is the same as basement stub.

Thank you much and I hope to figure this out for sure.