horizontal wet vent

[shamrock_94]

When our house was built a 3 pc rough in plumbing was completed in the basement. I have stubs for a WC, tub, and vanity. 5-6 feet away from the closest fixture is a 3" pvc pipe rising out of the concrete that is not a drain for the plumbing above. is this the vent for all three pieces? Can you horizontal wet vent a three piece bathroom? I was not able to check out the setup before the concrete was poured. thoughts...

 

[Jimbo]

A horizontal wet vent for a bathroom group is a very normal way to do it

 

[Sponsor]

 

[hj]

You cannot even be sure it is a "horizontal wet vent". A good plumber could install what you describe with the only wet vent being the section from the floor to the lavatory connection.

 

[Cacher_Chick]

While codes vary, more often than not a bathroom group will wet vent through the lavatory. If it is 3", that makes it even more questionable, as 2" is normally used for a wet vent. I have seen sewage basins with a 3" vent, but that is also uncommon.

 

[hj]

Sometimes they install a 3" vent riser with the intention of installing a 3" cleanout and then a 2" vent with the connection for the lavatory into the 2". That is the way I usually do it.

 

[shamrock_94]

I have attached a few pics to help explain. In the 2nd you can see the three fixtures:
Shower in upper right ,WC in middle and lav on the left. In 1st (taken 180 degrees from pic1a) The drain on the right is the drain from the 1/2 bath above. What is the 3.25 thinwall pvc pipe on the left? It runs up to the first floor, and I imagine to the roof. I was thinking is the vent for the basement bathroom group. What do you think?

 

[Jadziedzic]

That left pipe might be a radon gas vent pipe - take a look in your attic to see if it maintains the full diameter all the way through the roof. Check http://www.epa.gov/radon/states/michigan.html for a quick check if you live in an area with high radon levels.

 

[hj]

That drain in the upper right appears to be for a tub, rather than a shower, and whoever installed the piping did NOT do you any favors because the toilet and the tub/shower drain are both completely encased in concrete. The 3" pipe may be a Radon vent, and the 2" at the sink is probably also the vent for the bathroom piping.

 

[shamrock_94]

That drain in the upper right appears to be for a tub, rather than a shower, and whoever installed the piping did NOT do you any favors because the toilet and the tub/shower drain are both completely encased in concrete. The 3" pipe may be a Radon vent, and the 2" at the sink is probably also the vent for the bathroom piping.

You right it is a tub. I know the issue with the tub, since the trap in ecased in concrete, I can't get to the trap. (was still on the fence about installing a tub anyway) But what is the issue with the toliet? The trap for a toliet in in the toliet, right?

also, if the 2" for the sink is also the vent, I need to connect the vent with a vent to the roof, right? I suppose I can't use the "radon" pipe, and I can't use the 3" waste line from the 1st floor bath.

Arrgh! It looks like the $$ spent on the rough-in really didn't do that much help for me.

 

[Cacher_Chick]

A 3" WC riser should have a hub toilet flange installed, which must go around the outside of the pipe below the top of the concrete. To do this you will need to chip/cut/break the concrete around the riser. On a 4" riser, a flange can be installed to the inside of the riser, but on a 3" riser an internal mount flange causes an undesirable reduction of the inside diameter of the pipe.

It is pretty common in new construction to rough in the basement without putting in a vent through the roof. Adding a vent after the house is built is seldom a problem.