Under basement slab: p-trap positioning problems. Help appreciated!

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IndyGopher

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Plan to install a shower and freestanding tub in my basement. When I peeked in the boxes, I saw only horizontal capped 2" lines rather than p-traps. Is it typical to embed the traps in the slab after municipal inspection or should I assume I need to install traps? Or are you going to tell me the only way to find out is to open that pipe and run something through it?

If there are traps, should I be worried about how far they potentially are from the drain? I thought long horizontal runs before traps was a bad thing due to possible accumulation of gunk.

Thanks for opinions!
 

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Jadnashua

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Since the exact location of the trap and riser is dependent on the tub or shower you install, it would be kind of foolish to install the trap during the initial install of the trap arm. Now, whether they really have that line vented properly or not, you hopefully will see that pipe sticking up. On a 2" line, that must occur within five feet of the trap under the UPC code (further on IPC).
 

IndyGopher

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Since the exact location of the trap and riser is dependent on the tub or shower you install, it would be kind of foolish to install the trap during the initial install of the trap arm. Now, whether they really have that line vented properly or not, you hopefully will see that pipe sticking up. On a 2" line, that must occur within five feet of the trap under the UPC code (further on IPC).

Thanks for the quick reply, Jim. So I'll be installing traps at these drains. Got it. As for venting, my understanding is that everything is wet vented under the slap to dry vents off the two lavs we've got in the bathroom. The builder left two capped vents in the ceiling for those, so it's my plan anyway...
 

Jeff H Young

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I dont like to assume too much but if there isnt a trap in a tub box why would you suspect a trap? probebly no vent nearby either.
Is this a rough in for future bathroom that was already in house? And heck yea id run a tapemeasure or fish tape something down it . it wouldnt be smart to just build a bathroom only to find out later it was plugged with concrete 4 inches away. I know you think you are describing this well but the pic dosent tell a lot . No idea if its wet vented or not let alone properly the vents in the cieling would need to connect with something. But your basic question as to whether they would put a trap on typicaly? I would say no not typical To put a trap on something that you as a builder or plumber have no intention of completing just cap the end would be typical, also if there was a trap it should be in the box
 

Jeff H Young

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ok a little more info Those could be very simply 2 inch drainlines not vented at all just futures under slab. But Im not psycic it would take a quick look around to get an idea. also id suggest run a hose down full blast for awhile befor calling it good
 

IndyGopher

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Thanks a bunch for these additional replies this morning! Sounds like it's unlikely there's a trap further down the line under the slab, but I'll cut off the cap and run a tape measure through just to be sure.

As for venting, the builder knew the exact bathroom plan when laying plumbing under slab (the placements were all customized for future finishing). They tell me it's wet vented properly to lavs which will be vented to capped lines in the ceiling directly above. I can't be sure of that because I didn't see the plumbing before the foundation was poured, but it makes sense given what was left for finishing. I posted more pictures of the whole basement set up (2 bathrooms and a bar) in a thread a couple months back that didn't get much action, so I'd welcome any opinions based off that. https://terrylove.com/forums/index....-a-basement-with-2-bathrooms-and-a-bar.86682/

Thanks again!
 

Jeff H Young

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Ok great so you must have verticle pipe coming thru slab for the lavs that serve as vents
Thanks a bunch for these additional replies this morning! Sounds like it's unlikely there's a trap further down the line under the slab, but I'll cut off the cap and run a tape measure through just to be sure.

As for venting, the builder knew the exact bathroom plan when laying plumbing under slab (the placements were all customized for future finishing). They tell me it's wet vented properly to lavs which will be vented to capped lines in the ceiling directly above. I can't be sure of that because I didn't see the plumbing before the foundation was poured, but it makes sense given what was left for finishing. I posted more pictures of the whole basement set up (2 bathrooms and a bar) in a thread a couple months back that didn't get much action, so I'd welcome any opinions based off that. https://terrylove.com/forums/index....-a-basement-with-2-bathrooms-and-a-bar.86682/

Thanks again!

It looks good went to other thread terry had good advice . So I fully expect you need the trap . the other pictures helped a lot !
 

WorthFlorida

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How old is this home and what was or is this box used for?
A floor drain into a sump pump? If yes there be no trap anywhere.
Why is there water in it?
Do you know where this pipe leads to?

It must end up to the septic line or street sewer. Traps are always at the floor drain or fixture. Old homes before the 1960's had cast iron pipe and a 4" trap was installed where the pipe led out of the home. It is no longer required and can be removed.
 

IndyGopher

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@Jeff H Young : Thanks for taking a look at that other thread and confirming what Terry said! I'll expect to install traps at each drain, but I'll still double-check the interior of the pipes with a tape measure or something just to be sure.

@WorthFlorida: Thanks for checking in. The house is one year old and the pipes all lead to an in-floor basin where a sewage pump will be installed. That will pump to the main sewer line. The plumbing was all roughed-in to spec knowing that the basement would eventually be finished with 2 bathrooms.

As for why there's water in the box, I have no idea. This is my first time opening one of these, so is that unusual and/or very bad? I can reach out to my builder if there might be some huge issue. Anyone?
 

Jeff H Young

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didnt notice water but the boxes are watertite although they do crack and have nock outs and can easily leak water in around the pipe, Basements here are so uncommon to me but as a young kid we had a basement and lived in conneticut I remember moppping out water.
Any dampness in that box with a top box would be somewhat trapped . So since I dont even know a person with a basement Id be looking for sighnes of water coming in from the ground, grade arround the property, but I always look at that stuff. I think its a typical concern but might not be a typical problem .
 

IndyGopher

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didnt notice water but the boxes are watertite although they do crack and have nock outs and can easily leak water in around the pipe, Basements here are so uncommon to me but as a young kid we had a basement and lived in conneticut I remember moppping out water.
Any dampness in that box with a top box would be somewhat trapped . So since I dont even know a person with a basement Id be looking for sighnes of water coming in from the ground, grade arround the property, but I always look at that stuff. I think its a typical concern but might not be a typical problem .

Thanks again, Jeff. You've been beyond helpful. I feel a lot more confident about this thanks to you and everyone else who replied. The water table here in Central Indiana is extremely high, so I'm guessing it's groundwater that leaked in at cracks in the box and the opening around the pipe this past year. I don't see any signs of moisture in the basement -- floor or otherwise -- so I'm hopefully OK. Just didn't want to go ahead with finishing this up and cementing around that pipe if the water was a huge red flag to anyone.
 

WorthFlorida

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A one year old home and if it is a a new development, it takes awhile for the groundwater to drop. If there are little or no established lawns, the water has nowhere to go but down and until the soil packs around the foundation a lot of water will run down the wall into the french drain. That water is probably seeping in from under the slab.

I had new homes in Algonquin, Illinois and Syracuse, NY and it took about a year before the water slowed up from dumping into the sump pump. During a rain storm it sometimes sounded like a spigot was open echoing from the pit.
 

IndyGopher

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A one year old home and if it is a a new development, it takes awhile for the groundwater to drop. If there are little or no established lawns, the water has nowhere to go but down and until the soil packs around the foundation a lot of water will run down the wall into the french drain. That water is probably seeping in from under the slab.

I had new homes in Algonquin, Illinois and Syracuse, NY and it took about a year before the water slowed up from dumping into the sump pump. During a rain storm it sometimes sounded like a spigot was open echoing from the pit.

Ha, yeah you described my situation perfectly. One year new construction with surrounding homes no more than 2 or 3 years old. My sump pump works overtime after heavy rains for sure.
 

IndyGopher

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I'm back with another question. My Schluter kits come this weekend, so I was planning to use the materials as a template to set the traps. Problem is I just took the measurements and the boxes aren't deep enough for traps. I've only got 3 - 5" from the bottom of the plastic boxes to the center of the horizontal drain lines left in them. I tried removing the boxes, but they're firmly implanted in the concrete. Am I cutting out the bottom and digging a few inches in each?
 

Jadnashua

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You need to determine the depth needed for not only the trap but the height from the trap inlet to the desired height of the floor when the drain is added. The drain itself is 3-15/16" tall. https://sccpublic.s3-external-1.ama...d7/9000342159390/Shower System Data Sheet.pdf page 13. So depending on where the inlet to the p-trap is and the thickness of the foam pan, you may need to raise the floor some if the line is higher than desired. On their system, you can do that with a sheet of foam underneath the pan that you laminate in place with thinset. Make sure that the floor is both flat AND level before installing anything and pay VERY careful attention to getting the trap riser perfectly plumb. I think that I'd glue in the riser (you can always cut it off to the needed height afterwards, if required), place something over the top of it, put a bubble level on it, and then glue the trap into the trap arm. Hold the whole thing to keep the bubble level perfectly centered while the cement's solvent evaporates so that it doesn't move. Dry fitting just doesn't really work with PVC, so you have to measure carefully. There's very little horizontal leeway in the placement of the drain in the shower pan depression...maybe all of 1/4-3/8", if that. There's almost no vertical leeway. When calculating heights, keep in mind that there will be some thinset under both the shower tray and then on the drain itself. If you use the recommended trowel size, it should be less than 1/8" of thinset. If the floor is a little rough, you might need to go up slightly in trowel notch size to ensure full coverage.

If the pipe inlet does not have enough depth to attach a trap, then yes, you'll need to cut out the plastic box.
 

IndyGopher

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You need to determine the depth needed for not only the trap but the height from the trap inlet to the desired height of the floor when the drain is added. The drain itself is 3-15/16" tall. https://sccpublic.s3-external-1.amazonaws.com/sys-master/images/hc8/hd7/9000342159390/Shower System Data Sheet.pdf page 13. So depending on where the inlet to the p-trap is and the thickness of the foam pan, you may need to raise the floor some if the line is higher than desired. On their system, you can do that with a sheet of foam underneath the pan that you laminate in place with thinset. Make sure that the floor is both flat AND level before installing anything and pay VERY careful attention to getting the trap riser perfectly plumb. I think that I'd glue in the riser (you can always cut it off to the needed height afterwards, if required), place something over the top of it, put a bubble level on it, and then glue the trap into the trap arm. Hold the whole thing to keep the bubble level perfectly centered while the cement's solvent evaporates so that it doesn't move. Dry fitting just doesn't really work with PVC, so you have to measure carefully. There's very little horizontal leeway in the placement of the drain in the shower pan depression...maybe all of 1/4-3/8", if that. There's almost no vertical leeway. When calculating heights, keep in mind that there will be some thinset under both the shower tray and then on the drain itself. If you use the recommended trowel size, it should be less than 1/8" of thinset. If the floor is a little rough, you might need to go up slightly in trowel notch size to ensure full coverage.

If the pipe inlet does not have enough depth to attach a trap, then yes, you'll need to cut out the plastic box.

Wow, thanks @jadnashua ! This is pure gold and I'll definitely keep this post open and accessible as I do this work. I can see by your signature that you're well-schooled in Schluter. Really appreciate you taking the time to type all that out.

On another note, it's sort of a PITA to have to break open each drain box and dig when everyone knows a trap will need to be installed eventually. Is that standard practice, or did my builder/rough-in plumbers mess up in either depth or waste pipe placement? Just seems like something that could be done easily during building, but which every plumber would curse about afterwards during trap and drain install.
 

Jeff H Young

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Wow, thanks @jadnashua ! This is pure gold and I'll definitely keep this post open and accessible as I do this work. I can see by your signature that you're well-schooled in Schluter. Really appreciate you taking the time to type all that out.

On another note, it's sort of a PITA to have to break open each drain box and dig when everyone knows a trap will need to be installed eventually. Is that standard practice, or did my builder/rough-in plumbers mess up in either depth or waste pipe placement? Just seems like something that could be done easily during building, but which every plumber would curse about afterwards during trap and drain install.

The box marks the spot , if the end of the pipe is in there and it can be dug out without a jack hammer Id call it good. not a screw up , they dont care , close enough , good enough go to the next house , boss breathen down your neck hurry up. Where I live they have piece workers on new tract homes and illegal aliens putting it in gotta be fast or youll starve.
 

IndyGopher

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@Jeff H Young , thanks again. You've been a great participator in this thread and I really appreciate it!

To all, I'm bumping this again because I've got a new question. Basically, in addition to post #17 above (the tub boxes aren't deep enough for the p-trap), I received my Schluter trays this week and discovered that I also won't be able to place the p-traps in a position where they'll be centered and plumb through the tray. I'll post some photos below to try and demonstrate, but basically if I hold the trap all the way back to where the drain pipe enters the drain box (the earliest possible connection point for me), it still sticks out way past center of the Schluter tray. I'm told there's not much play with drain placement on these kits...so my questions:

1) Is the best (only?) solution to bust out some concrete on the sewer side of that box in order to access the drain pipe further upstream and make the p-trap connection in a spot that will have it centered?

2) Am I right in assuming I also need to cut out the bottom of those plastic drain boxes and possibly dig a few inches to place the traps on the same horizontal as the line coming in?
 

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Jeff H Young

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Break out whatever is in way of putting trap where you want it bottom or sides
 
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