Bathroom remodel - interesting find under pre-fab shower

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rhwimmers

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On the other side of that wall is the HVAC room - there is a floor drain in that room too but not sure if it "T's" with this shower drain we're looking at, or if they both just run and dump into the grinder sump and/or regular water sump. I'll confirm which one that floor drain goes to (guessing it's the regular sump pump since no poo should ever get waffle smashed into that floor drain # ; ) ha!
If there is a vent in the grinder sump, would that suffice? Just curious as we had no issues with inspection when we purchased the house in 06.
Cutting more concrete and putting in the AVV into that wall wouldn't be too terrible if we determine thats necessary. On the other side of the HVAC room is the crawl area and easy access to port things outside if needbe.
Thinking back - that bathroom would occasionally smell like poo..but it just rarely gets used and hardly an issue so we would just run water down the pipe or cover the drain as an easy fix.
"you could install a wye in place of the 45 elbow" - do you mean a standard plumbing "Y" piece where it splits the PVC, one side going to the P-trap and shower drain, the other side going into and up the wall to the AVV?
 

rhwimmers

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Ah - thanks for the pic - we posted at the same time. I just measured and its closer to 30' from drain to sump/grinder area.
The wall you depicted is a solid concrete wall and foundation in basement. The wall on the left with holes in it and on the bottom is the HVAC room. I think either wall would work fine as it just sits in the wall it appears. The vents would need to be visible / in open "air", is that right? We will likely be tiling the walls or have the pre-fab shower walls...but the vent does need to be accessible/viewable? I suppose I could have the visible vent side on the other side (in the HVAC room) to avoid needing to go too far with breaking the concrete floor?
 

MicEd69

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Oops, I messed up. The vent has to come off the top part of the drain line, no more than 45 degrees off vertical. So, my sketch will not meet code. I was in a hurry to get a sketch out to you without thinking this through.

So, hopefully, the existing drain line goes under a wall no more than 8 feet from the P-trap. At that point, you will need to break up the concrete under that wall, install a sanitee to the existing drain line and install the AVV in that wall. And yes, it can face either direction. The link I included has a louvered cover, so if that room is finished, it won't be too unsightly.

If there is no wall, I think you will need to break up more concrete such that the drain line will flow toward the HVAC wall where the vent line can be installed, then swing it around to meet the existing line father downstream. But if that is required, you need to use 45 degree and/or long sweep fittings. I'll get a sketch together in a bit with a suggestion for this approach.

Sorry for the confusion.

Re: why this wasn't discovered in your home inspection. Home inspectors vary in how much of the details they investigate. A P-trap is easy to verify, but the presence of a vent is more difficult. But as Twowaxkack said, "Amateur work at its finest." And my concern would be that if the bathroom looks like an amateur did it, a good inspector should/would check for things like traps and vents.
 

rhwimmers

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Yes this bathroom is 5'7" x 8'5". So in the picture you sketched up, its 5'7 on the wall with the blue AAV drawing, and 8'5 from the hole in the wall where it says AAV to the other wall (also concrete/foundation wall). So where I would put the p-trap in the current hole in the floor to the nearest wall towards the grinder sump is just a few feet....So I think your drawing would be accurate where id need to break up more concrete for the red PVC on the left
 

MicEd69

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Yes, it sounds like running the P-trap at a 45-degree angle towards the HVAC wall is the way to go. The line only needs to run down that wall a foot or so to get the sanitee in and run the vent up to the AAV in that wall. Then come out of the wall at another 45-degree angle until it hits the existing drain line. That means several feet of concrete needs to be broken up. I’m not sure what that angle will be when the new line hits the existing drain line, but there are ells with various angles available. I know it’s tempting to shorten the length of new drain line and concrete demo and use 90-degree ells but don’t.

Be sure you maintain ¼ inch per foot slope in your drain line. Put sand under the new drain line to provide good continuous support. Then cover the pipe with sand after the slope is verified. Since some of this will be outside the shower, you should put 3-4 inches of concrete over the sand covering the pipe.
 

rhwimmers

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Ok so back to this project # ; )
I decided to knock out concrete to make enough room to put a Ptrap in this area where the PVC is.


The problem I have now is the height of the existing hole (bottom of pic, which runs to sump) is a little too low so on the other side of ptrap and into the shower drain the height is off by about 1/4-1/2". Wondering if I just use a black plastic coupling piece so it can allow for a little give? Id rather not raise the shower pan up if I dont have to, then i'd have to put quarter round around the base or something to hide that gap and it'd be that much higher of a "step" to get in shower.
 

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Here is a pic of what I got going right now... Seems like it might be OK? Its definitely tilted slightly down on the drain side but it should move up a little when I screw the base from shower in from above (it should pull it up 1/4" or so) as the drain hole in the base is not flush with the ground... Hope that makes sense.
 

MicEd69

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You still need a vent between the P-trap and the connection of the drain line to the sewer. It must go vertically off the drain line or a maximum of 45 degrees off vertical. And it must be within 8 feet of the trap weir, that is the 90 that attaches to the drain line at the bottom of your picture. See my Feb 1, 2022 post sketch above in this string of posts.
 

rhwimmers

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I've since been told that since this drains to the sealed sump, which has a vent, is how it's to code and gets the vent 🤷
 

MicEd69

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I guess I missed that you had a sanitary sump. However, I've got a few questions:

1 - Are there any other fixtures flowing into the line from the shower to the sump?
2 - How far is the shower line from the sump?
3 - Do any toilets flow into the sump?

Just because the sanitary sump is vented doesn't necessarily mean you do not need to vent some of the fixtures that flow into the sump.
 

rhwimmers

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The toilet which is right next to the shower. There's another floor drain in the HVAC room right next to this bathroom but I'm fairly certain that one just runs to the sump, and not to the grinder/sump where the drain runs.
2. Probably about 15'
3. See 1 🤣. Yes
 

MicEd69

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If I understand your answers correctly, the possible issue you have is that the toilet can pull the water out of the shower P-trap as it is in the same line as the shower before it goes into the sump. I assume the line is 3" from the toilet and the 2" shower drain combines with it. pretty much at the toilet. If you lose your P-trap seal, you will possibly get a sewer gas smell in the shower.

It might not happen, but I don't think it is per code. Other's may want to comment on this who are more familiar with sanitary sumps.
 

rhwimmers

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Yeah it's about a 3' section from toilet to shared drain.
Any thoughts on my recent pic and if that's gonna be fine as is as far as the height being off slightly?
 

MicEd69

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It depends, as it isn't super clear in the picture. Here is a picture of the P-trap requirements per code.

1673810541678.png

It isn't the best that your shower drain doesn't go straight down into the P-trap, but besides that, it appears from the picture that the horizontal line from the shower connection to the P-trap is lower than the P-trap connection to the drain line going to the sump. Is that the case?

If so, you do have a BIG problem. See my marked-up sketch below.

1673811932503.png

That section of horizontal piping cannot be left full of water. But if the horizontal line to the P-trap is higher than the drain line, for the short distance of the shower to P-trap, a 1/4" difference isn't the best, but probably won't hurt anything.
 

rhwimmers

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Yeah I wish I could go straight down into ptrap but that corrugated pipe around the perimeter is in the way. I'll confirm there won't be water in the horizonal section. Thanks so much for the help and ideas!
 

MicEd69

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I'm assuming that corrugated pipe is perforated and completely encircles your basement and leads to a ground water sump. Sometimes, those pipes don't actually flow into the sump, but they are there just channel the ground water over to the sump that sits in a French drain of sorts. And the sump is simply a perforated container that sits in that French drain so there is a place for the sump pump to take suction and properly cycle to remove the ground water from under/around the basement. If that is the case, there is nothing sacred about that pipe. If it were mine, I would cut that perforated pipe, cover the ends with some fiberglass woven cloth or just the panty section of some old panty hose, and install the P-trap directly under the shower base. That approach shouldn't hurt either your subsurface water system, and it would be better for your shower drain operation.

Just something to think about.
 

rhwimmers

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The corrugated pipe continues to the left, it goes all around the perimeter and dumps into sump (which is next to the grinder sump where the shower/toilet drain into. So I think that might be bad to block that connection if the ptrap fire right under the shower drain?

Here is the sump, it unfortunately went out last night so just put this in this morning🤬


Is there a reason the sump caps are a solid piece and not 2 halves? It would be SO much easier to do the plumbing if you could just take the cover off without messing with unions etc
 

rhwimmers

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Checking back for any thoughts/ideas? I think the main question/struggle I have right now is this. The pipe that goes to the sump is only about 1 3/4" below the ground. Does that mean if I plumb it "flush" the other end of the ptrap will also be 1 3/4" under ground, in other words is the ptrap "level"? When playing around with pipes and everything it seems like the shower side of the ptrap will be up above the ground level which I would like to avoid otherwise ill have to lift the shower pan (pre-fab shower) etc...
I think i'm finding out the hard way why the initial installers took a shortcut without a trap.
 

MicEd69

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Depending on the levelness of your basement floor, you could be right. But the dimensions you've provided don't compute.

From your earlier posts/answers, the line into your sanitary sump is 3" and runs about 12 feet from your toilet. While I like to run 3" at 1/4" per foot slope, some codes allow 1/8" per foot. The minimum fittings for a toilet, a street 90 and a toilet flange, measure 5" from the top of the flange to the centerline of the horizonal pipe, or 3 1/4" to the top of the pipe. Using the 1/8" slope, that's 1 1/2" for 12 feet. So that would put the bottom of your toilet about 6 1/2" above the top of the pipe entering your sanitary sump. But that's a LOT of slope for a basement floor!

Sound like you need additional investigation of the piping.
 
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