I'm installing a master bathroom in a concrete slab. Unfortunately I've already poured the concrete. Along one wall from upstream to downstream I have a jetted tub, shower, and then the toilet. The sink is across from the shower. At the moment each fixture has its own vent. I'm trying to get rid of the tub vent because I'm having problems lining up the drain with my tub. I bought the tub after the installation was done (not smart).

If I can eliminate the tub vent life would be better for me. Can I use the downstream shower vent as a horizontal wet vent? The tub has a 1-1/2" trap that drains into a 2" line. Downstream of this 5.5' is the vent/drain the shower feeds into. The shower has a 2' p-trap and drains into 2x2x1-1/2" T. The 1-1/2" portion is the vertical venting for the shower. This drains down into the 2" horizontal line from the tub. Then this leads to another 2" vent downstream that the toilet drains to - of course it's 3' line after the toilet. So can I eliminate the tub vent and use the shower vent? Hopefully all that makes sense.

I..............I..................I
I..............I..................I
I.....tub.....I....shower....I
I--u..........I--u.............I--toilet
I_________I___________I__________

If that drawing makes any sense (u's are p-traps and I's are the vertical vents. and ignore the "periods" - I had to do that because the formatting got screwed up) can I remove the first vent serving the tub. It's 5.5' downstream to the 1-1/2" shower vent.

thanks

Steve

speedball1

Good morning Steve,

Since you won't be discharging a major fixture, (toilet) past your tub I can see no problem in using the shower vent to wet vent the tub. You're a little long on distance, (code calls for 5' from trap to vent) but that shouldn't be a concern since It's my bet the job's not gonna be inspected anyhow. Good luck, Tom

schnur777

Well actually I did have it inspected and they approved it the way I had it. But I'd like to remove the first vent now. So you're saying I'm limited to 5 feet between the drain of the tub and the downstream vent? I have no idea if they will notice that I removed the vent or not. They've already approved the below slab drainage but they'll be back for the supply lines and final plumbing inspection.

Actually, the way I originally had it for the first inspection was without the shower vent. I had the tub vent and the toilet vent and the inspector said I couldn't use the toilet vent as a wet vent for the shower. I thought he was wrong on that, but since this is my first time plumbing I had no grounds to argue with him.

speedball1

Since we have permits and inspections involved your going to have to check local codes to find out if a toilet vent's mandatory. In my area a separate vent isn't called for. Your inspector was correct. If the toilet vent was upstream from the shower tie in you would have been discharging a major fixture past a unvented minor one.
If all you have left is the "Trim Out Final" inspection then the walls should have been covered up and the vents concealed. Most of my questions don't come in about jobs that have had permits pulled and I can be a little loose in interpreting code. I can just refer to my Standard Plumbing Code Book. However, with permits and inspections local codes kick in and there I'm flying blind. I can't advise a asker if he has to follow local codes. I would eliminate the tub vent as unnecessary but that's following my set of codes. If yours calls for it you will have to keep it it. Good luck, Tom

schnur777

When the inspector came to inspect my plumbing the first time, I had a vent for the tub (which is the most upstream fixture), with a 1-1/2" trap feeding into a 2" horiz drain, then I had the shower feed into this same drain about 5.5' downstream, then about 3' feet downstream from that is the vent for the toilet which feeds into a 3" line. He said the shower had to have its own vent - I thought the next downstream vent would suffice. It appeared to agree with the drawings and discussions I have in my plumbing book regarding wet vents.

I think I'll just have to go down to their office and talk them.

Thanks for all your help.

flamingofarm

Been reading everyones input on venting certain projects, thought you might be interested in this and be interested in comments. Ten years ago I put a basement toilet, shower and lav and on the back of the toilet wall put a small bar sink. All the drains run under the cement floor into a sewage pump, the pump itself has wet or dry vent (not sure which is which) that comes out of the crock and enters the top of the waste line. Other stuff is vented with a 1-1/2 vent stack that comes up from the floor, up the wall which has the drain for the small bar sink, vent pipe goes up and again enters the drain line from the top. System generally worked just fine, never had a problem except, every so often some sewage water would come up thru the bar sink drain! Over the years you would not believe all the suggestions that were offered as to the cause. I found out that the vent stack I spoke about (coming into the top of the waste line) would generally work just fine except everyone seemed to forget that a sewage pump pumps a huge amount of waste water very quickly with a great deal of thrust and that volume I think just sometimes got pushed up into the vent line and dropped down to the bar sink drain and bubbled up! There is simply no other way water could back up into that bar sink, once the pump comes on it is pumping stuff out of the crock, not back into the various fixtures. What I found digging a round was that the vent into the waste line was not taken high enough, actually from the center line of the waste line, I bet the height of the elbows do not reach three or four inches and there actually is another good four inches in height available. This needs to be corrected and am sure that is the reason. I disconnected that elbow system and capped it off and put an auto vent on the vent pipe until we can do it over. I find the auto vent works just fine, everything works well and guess what, have never had waste bubble up in the sink! I am not sure the auto vent should be the way to vent his permanently even though it works, I think the idea of running that vent stack up as high in the floor rafter as it can go and then into the top of the waste line is the best way, even putting a Y in the waste line with the branch pointing opposite from the flow and then tying the vent into that wye fitting. I think that design rather than just a TY might just add some security that with the higher vent configuration you have a design less likely to be affected by the volume and thrust of the water. Keep in mind that when the pump comes on, all this water under force comes up into the waste line and moves only a few feet before passing by the vent. After all this time and all the discussion, this is how I found out how and why this waste water was getting down into the bar sink drain causing it to back thru the drain. What is interesting is that is did not always do it, the more the system was used it seemed to occur less for whatever reason. Since the bath downstairs is used maybe once a month, it never failed that someone would be at the bar and someone using the toilet, the pump would come on and you could hear it coming into the bar drain. Not real pretty. Be inerested in some feedback.

Dave Doran