Bathtub to Shower Venting On Slab

[Alecstar]

Hello and thanks in advance to anybody who responds. My home is 5 years old and on a slab. I removed the whole acrylic tub and walls unit and am putting in acrylic shower pan with tile. I have seen enough Holmes HGTV to know that there has to be air behind water. I removed everything and what you see left is the bath-tub drain along with the tub overflow drain. They both connect to an elbow that connects to a pipe that goes straight down (13"} into the plastic lined hole you see in the picture. Beneath that I have no idea. I always thought plumbing had to have a trap and a vent. Could it be that the tub overflow is serving as the "air vent"??? Also where is the trap? I don't want to go any further with this until I know what to do. Are new slab homes built differently in this regard. I have to break some concrete up to move the drain slightly as well as lower it. Any suggestions are greatly appreciated. Thank you

 

[Jeff H Young]

the verticle pipe coming up through slab is typicaly 99.9 percent of time connected to a p trap. It very well could be properly vented , you never know but if you dont know what your looking at I wouldnt assume its wrong. Lastly an overflow is in no way a vent forget that Idea

 

[Sponsor]

 

[wwhitney]

At the bottom of the hole, remove the soil between the vertical pipe and the little bit of horizontal pipe you can see that is not immediately adjacent to the vertical. I bet you will find that soil was covering the u-bend of a p-trap.

Cheers, Wayne

 

[Alecstar]

Okay, so the trap is below what you see in the picture. What about the vent??? If in fact the builder used the tub overflow pipe as an air vent (technically that would work I suppose) is that legal by plumbing standards? Thank you for your responses.

 

[Jeff H Young]

The "Trap arm " goes toward the vent bust floor out follow that pipe to find the vent . but id open floor cut old trap off and run horizontal pipe to where new drain will be. note: do not offset the horizontal trap arm up higher. also note there is no cookie cutter answer to your questions with no sketch or photos of where other pipes are . NO A OVERFLOW IS NOT A VENT it was not put there as a vent its called an overflow and is only an overflow. You keep thinking your house is plumbed wrong but I see nothing to indicate that

 

[Alecstar]

The "Trap arm " goes toward the vent bust floor out follow that pipe to find the vent . but id open floor cut old trap off and run horizontal pipe to where new drain will be. note: do not offset the horizontal trap arm up higher. also note there is no cookie cutter answer to your questions with no sketch or photos of where other pipes are . NO A OVERFLOW IS NOT A VENT it was not put there as a vent its called an overflow and is only an overflow. You keep thinking your house is plumbed wrong but I see nothing to indicate that

Guess what? That overflow arm was used as a vent. Now that the tub/overflow is gone and there is just a shower pan... it makes noise when draining. Since its on a slab there is no way I can see to fix it without doing a whole lot of damage first. At least it drains... even if its noisy.

 

[Jeff H Young]

pipes will allways drain if it has fall and isnt plugged. un vented is what I call what you desribe so if you demoed all the walls and coudnt find a pipe in the slab for a lav or anything withen around 5 or 6 feet then you are right its unvented