My house was built few years ago and it has rough in plumbing in the basement for the bathroom. I am in the process of finishing the basement and I am not sure if I need to add vent or not. I am assuming that the builder took care of the venting, when they did the rough in plumbing for the bathroom. Am I correct to assume that?

Look for the lavatory rough. If you see a tee with a stubout coming off the branch and a pipe going up from it chances are you're vented. If there's nothing but a 2" pipe in the wall then must complete the stub-out and vent yourself. You have options here. You may run the vent out the roof or you may revent back to a dry vent in the attic. Another option, if local codes allow) would be to install a AAV,(air admittance vent,) just behind the trap.(see image). Good luck, Tom

Hi all:

Here is a picture of a basement bathroom rough in that was NOT completed by the plumber. Plumbers do NOT usually complete the vent work for future bathrooms.

In the case below, the box out in the floor is for a tub or shower and the largest pipe is obviously for the toilet. The two pipes in the wall are 1) tub vent (left pipe in wall), and 2) the lavatory waste and vent WHICH ALSO ACTS AS A WET VENT FOR THE TOILET.

In some bathrooms you will only find a 2" pipe...this pipe will pick up the lavataory and then run full size 2" until it connects into another 2" vent...exactly as Tom described.

In some bathrooms, you may have more than the 2" vent... like in the bathroom below. In this case you would connect the vents together at about 42-48" off the finish floor (and hook up lavatory drain) much like I have drawn in red below.

Hope that helps you determine your specific layout... ;)

Let us know if you have more questions...

MARK

Here is the pictures of my layout. The hole in the floor is where the drain is for bathtub, the pipe is buried under few inches of gravels and it is in horizontal position.

Based on the pictures, what is the best way for me to tie in the vents or how I should do it.

Thanks for your help.

http://my.ilstu.edu/~ughamme/two.jpg

http://my.ilstu.edu/~ughamme/one.jpg

You will connect the PTRAP at the box in the floor.. and then connect that to the tub waste...

If there is only the one 2" vent then you need to install a 2"x1.5" sanitary tee fitting at about 18" to center from the finish floor and stub out for the lavatory and then run the 2" vent up to connect into another 2" vent upstairs or in the attic. If no vents close by, then you may also need to run the vent up and out the roof by itself... but better if you can connect into a 2" vent that already exists.

That should be all you need to do... as long as there are no other vents missing from the picture.

Any more questions.. Let us know...


MARK

Quote:

---

Originally Posted by massplumber2008

You will connect the PTRAP at the box in the floor..and then connect that to the tub waste...

If there is only the one 2" vent then you need to install a 2"x1.5" sanitary tee fitting at about 18" to center from the finish floor and stub out for the lavatory and then run the 2" vent up to connect into another 2" vent upstairs or in the attic. If no vents close by, then you may also need to run the vent up and out the roof by itself...but better if you can connect into a 2" vent that already exists.

That should be all you need to do...as long as there are no other vents missing from the picture.

Any more questions...? Let us know...


MARK

---

Thank you for taking your time modifying my picture to show me the way it can be done, that helped a lot.

There are no vent pipe in the basement looking up to the ceiling because they are all from first floor and up. I see a 2 inch pipe coming down from the kitchen sink and it is connected to the main waste pipe. If I connect to that in a way that the waste from the kitchen sink will not go back to the vent for the basement bathroom, will that serve as a vent? I can take a picture of this, if you want.

If the above method is not acceptable, then how about this. I have no clean way of installing a vent pipe all the way to the roof because this house is a two story. What I can do is to run the vent pipe all the way to the garage and then through the roof like how they did with radon remover system; however, there will be at least 5 90 degree bends in order for me to route it out through the garage.

Third option, is it possible to vent it out the side of the house?

Is there any other option that I could explore?

I think I found the vent pipe. Picture below shows a drain pipe for the kitchen sink, and there is another 2 inch pipe that is capped off. Is it possible that the plumber put it there for the basement bathroom vent?

http://my.ilstu.edu/~ughamme/three.jpg

That is called a FUTURE VENT... I think you just lucked out BIG TIME! Remove the cap.. there should be some water in the pipe due to rain water. If so, hook onto this and you're all set!

Good for you!

Awesome Awesome!! Thanks a million. :)

Pop back if you have any more questions... glad to help!