Moving Toilet Location Under Slab

[Girafdaniels]

I’m moving a toilet location about 5 1/2” away from its previous center. The current set up has a 2” outlet off the back of the 90. That 2” pipe is a vent that turns up the wall straight behind the toilet.

The new center of the drain will be back and to the left, and I’m unsure of the best way to approach it. I am sure, whatever the case, I’ll need to open up the floor some more to make anything work.

The first thought is to use another 90 with a 2” outlet, and just use a combination of 45’s / 22’s to get me back in line with the existing drain/vent pipes.

The other idea is to use a wye, 45 off the wye and then two 22’s to get to where I’d need to be for the 90 turning up, then I’d just run the straight pipe back to the vent line.

Hopefully this makes sense and the photo mark ups help. Really appreciate any advice. Several of you have already steered me in the right direction with other questions in this bath/laundry remodel! Thank you!

 

[Plumber69]

Just use a wye, then a street 45 or 45 then 90 up to toilet. Easy peasy. The difference between the 45 and street 45 is probably 1 1/2

 

[Sponsor]

 

[Terry]

You never use a santee on it's back for a toilet. The poop spreads out both directions.
Use a wye off the line and bring the toilet up with a 90. Plumber69 has it right.

I don't know who thought a flat vent below grade was good though. If that was a lav, at least it would be washed and have access for snaking.

 

[Girafdaniels]

Just use a wye, then a street 45 or 45 then 90 up to toilet. Easy peasy. The difference between the 45 and street 45 is probably 1 1/2

Thanks for the good advice. A street 45 will still kick me out too far to the left though (and be too close to that wall), so I’d need to run a couple 22’s to draw it in tighter to the current line. Would those slight turns (like I have pictured) create clog potential?

 

[wwhitney]

How far to the wall from the saw cut in the top of your picture? And how deep from the top of slab to top of the 3" pipe?

Ideally you'd eliminate the flat vent by breaking the concrete to the wall. Then at the bottom of your picture, you'd have a 3x3x2 wye, with a street 45 in the 2" side branch, rotated so the 2" inlet is parallel to the 3" inlet. That wye/45 assembly wouldn't be flat, you'd roll up the 2" inlet until the bottom of the 2" inlet on the wye is above the midline of the 3" through branch. (Bottom looking through the interior of the 3" through path on the wye, so the 3" through path is at least an uninterrupted half-pipe.)

Then your 2" line could continue horizontal (2% slope back towards the 3" line) until you get to the wall, where a long turn 90 will turn up into the wall and then you reconnect to the 2" line in the wall. The 3" wye inlet can hit a 45 at the right place to hit your toilet location.

That's proper way to do the venting, I don't have enough experience to know how much concrete it's worth breaking in order to fix your venting.

Cheers, Wayne

 

[Girafdaniels]

You never use a santee on it's back for a toilet. The poop spreads out both directions.
Use a wye off the line and bring the toilet up with a 90. Plumber69 has it right.

I don't know who thought a flat vent below grade was good though. If that was a lav, at least it would be washed and have access for snaking.

Thanks for the confirmation. There’s a lot of very questionable building choices in this house. Been a ton of fixes since buying it and making discoveries.

 

[Girafdaniels]

How far to the wall from the saw cut in the top of your picture? And how deep from the top of slab to top of the 3" pipe?

It’s 6” to the wall and the top of the pipe is 4 1/4” down from the top of the slab.

All of that makes sense, though getting into the wall wouldn’t be my preference! I’d have to see how that would all line up with parts in hand, too.

I don’t think the current situation, venting included, has created any problems over time. It hasn’t anyway, that I’m aware of, in our 4 years here. What could I anticipate going wrong if it stays flat (so I avoid extra work!)?

Thanks much for the help.

 

[Girafdaniels]

Thanks for the confirmation. There’s a lot of very questionable building choices in this house. Been a ton of fixes since buying it and making discoveries.

You never use a santee on it's back for a toilet. The poop spreads out both directions.
Use a wye off the line and bring the toilet up with a 90. Plumber69 has it right.

I don't know who thought a flat vent below grade was good though. If that was a lav, at least it would be washed and have access for snaking.

Would it make sense to add a clean out plug in the wall where the vent runs up?

 

[wwhitney]

It’s 6” to the wall and the top of the pipe is 4 1/4” down from the top of the slab.

OK, the "upright wye" configuration of a 3x3x2 wye and a 2" street 45 has a center to center spacing of 7" on the parallel 3" and 2" inlets. If you roll that up 30 degrees (assuming that's enough), the center would rise 3-1/2", but the pipe is 1/2" less in radius. So you'd end up 1-1/4" clear below top of slab. Maybe that's fine.

All of that makes sense, though getting into the wall wouldn’t be my preference!

Shouldn't be too bad if it's a wood framed wall, it's OK to cut out the bottom plate between studs, the bottom plate doesn't do much structurally. Worst case you'd want to add some tap cons to the new cut ends of the bottom plate. You could cut out 4" of bottom plate length and chip out a 4" channel for the 2" pipe, I think that would give you enough working room.

I don’t think the current situation, venting included, has created any problems over time. It hasn’t anyway, that I’m aware of, in our 4 years here. What could I anticipate going wrong if it stays flat (so I avoid extra work!)?

That I don't know, I don't have the hands-on experience, somebody like Terry could tell you. If you leave the flat venting, then the clean out in the wall is a good idea and should let you easily clear the vent if it becomes blocked below the slab.

Cheers, Wayne

 

[Jeff H Young]

Poor workmanship! I would recomend the fix wayne said and put a clean out. some factors could allow this to operate with little trouble but I wouldnt count on it. If you do like wayne said you wont have a problem at least not with what is shown

 

[Jeff H Young]

Poor workmanship! I would recomend the fix wayne said and put a clean out. some factors could allow this to operate with little trouble but I wouldnt count on it. If you do like wayne said you wont have a problem unless there is something else wrong

 

[Girafdaniels]

OK, the "upright wye" configuration of a 3x3x2 wye and a 2" street 45 has a center to center spacing of 7" on the parallel 3" and 2" inlets. If you roll that up 30 degrees (assuming that's enough), the center would rise 3-1/2", but the pipe is 1/2" less in radius. So you'd end up 1-1/4" clear below top of slab. Maybe that's fine.

Wayne - Thank you for the detailed responses! If I can pour 1 1/4" of new concrete on/around that vent line and have it be fine, then that's the route I'll take. Btw, is a long sweep 90 necessary to turn up the wall? There's no way it will ever be used as a drain (by me or any future owner). Going with a regular 90 in that tight space may be easier...

Shouldn't be too bad if it's a wood framed wall, it's OK to cut out the bottom plate between studs, the bottom plate doesn't do much structurally. Worst case you'd want to add some tap cons to the new cut ends of the bottom plate. You could cut out 4" of bottom plate length and chip out a 4" channel for the 2" pipe, I think that would give you enough working room.

Right, it won't be too much more work. A good reminder as I'm inclined (like many) to think it will be more than it actually will be. But I'm also very keen to limit extra work!

That I don't know, I don't have the hands-on experience, somebody like Terry could tell you. If you leave the flat venting, then the clean out in the wall is a good idea and should let you easily clear the vent if it becomes blocked below the slab.

I'll add the clean out as a precaution.

 

[Girafdaniels]

Poor workmanship! I would recomend the fix wayne said and put a clean out. some factors could allow this to operate with little trouble but I wouldnt count on it. If you do like wayne said you wont have a problem at least not with what is shown

Poor workmanship has unfortunately been the rule at this house. I'm going to have to add a couple 22's to the 3" inlet on the wye before turning it up with the 90 so the new center is in the correct place. And I'm anticipating some slight bends to get the down line 3" pipe and 2" vent to line up. At any rate, appreciate your seconding of Wayne's suggestion. I'll post a finished pic (hopefully by end of day tomorrow, if all goes well)!

 

[wwhitney]

Btw, is a long sweep 90 necessary to turn up the wall? There's no way it will ever be used as a drain (by me or any future owner). Going with a regular 90 in that tight space may be easier...

It's required because it's below the toilet flood rim level. If you get a clog in the 3" line and the toilet backs up, then it could back up into that 90. So the idea is that it should be designed to drain easily.

I'm not quite experienced enough to know if using a medium 90 there is a reasonable corner to cut, but if there's a cleanout above it, that certainly mitigates the down side. Part of the reason I suggested cutting out the whole width of the bottom plate was so that you could slide the long turn 90 back as far as possible to get it to fit without interfering with the wall covering. If you are going to have a baseboard there, it would be OK for the bend of the 90 to protrude somewhat out of the framing.

Similar consideration for how much to roll the upright wye above horizontal. The code requirement is that bottom half of the pipe is solid so nothing flowing in that part can clog the vent takeoff opening. If you can do that and not be so high in the slab as to make the concrete cover too thin, great. If not, you have to pick the right trade off.

Cheers, Wayne

 

[Jeff H Young]

It's required because it's below the toilet flood rim level. If you get a clog in the 3" line and the toilet backs up, then it could back up into that 90. So the idea is that it should be designed to drain easily.

I'm not quite experienced enough to know if using a medium 90 there is a reasonable corner to cut, but if there's a cleanout above it, that certainly mitigates the down side. Part of the reason I suggested cutting out the whole width of the bottom plate was so that you could slide the long turn 90 back as far as possible to get it to fit without interfering with the wall covering. If you are going to have a baseboard there, it would be OK for the bend of the 90 to protrude somewhat out of the framing.

Similar consideration for how much to roll the upright wye above horizontal. The code requirement is that bottom half of the pipe is solid so nothing flowing in that part can clog the vent takeoff opening. If you can do that and not be so high in the slab as to make the concrete cover too thin, great. If not, you have to pick the right trade off.

Cheers, Wayne

Right on with your assesments wayne! Ive used a medium sweep but if at all posible avoid and go long sweep. You can be almost to the top of slab because even if part of the 90 just barely sticks out the wall there will be drywall and flooring then a base board. for the sake of a good vent that has 1/4 inch per foot fall rolled up proper take this into concideration just a tiny bit out the bottom inch could help. But thats just how I roll (pun intended).

 

[Girafdaniels]

It's required because it's below the toilet flood rim level. If you get a clog in the 3" line and the toilet backs up, then it could back up into that 90. So the idea is that it should be designed to drain easily.

I'm not quite experienced enough to know if using a medium 90 there is a reasonable corner to cut, but if there's a cleanout above it, that certainly mitigates the down side. Part of the reason I suggested cutting out the whole width of the bottom plate was so that you could slide the long turn 90 back as far as possible to get it to fit without interfering with the wall covering. If you are going to have a baseboard there, it would be OK for the bend of the 90 to protrude somewhat out of the framing.

Similar consideration for how much to roll the upright wye above horizontal. The code requirement is that bottom half of the pipe is solid so nothing flowing in that part can clog the vent takeoff opening. If you can do that and not be so high in the slab as to make the concrete cover too thin, great. If not, you have to pick the right trade off.

Cheers, Wayne

More great advice that makes sense. Ideally, I’ll have it all pieced in today. I may go ahead and upload a pic before gluing all in place!

 

[Girafdaniels]

It's required because it's below the toilet flood rim level. If you get a clog in the 3" line and the toilet backs up, then it could back up into that 90. So the idea is that it should be designed to drain easily.

I'm not quite experienced enough to know if using a medium 90 there is a reasonable corner to cut, but if there's a cleanout above it, that certainly mitigates the down side. Part of the reason I suggested cutting out the whole width of the bottom plate was so that you could slide the long turn 90 back as far as possible to get it to fit without interfering with the wall covering. If you are going to have a baseboard there, it would be OK for the bend of the 90 to protrude somewhat out of the framing.

Similar consideration for how much to roll the upright wye above horizontal. The code requirement is that bottom half of the pipe is solid so nothing flowing in that part can clog the vent takeoff opening. If you can do that and not be so high in the slab as to make the concrete cover too thin, great. If not, you have to pick the right trade off.

Cheers, Wayne

Pictures before glue up! I’m using oatey’s heavy duty glue and primer. Any special considerations I need to make for gluing, etc. below slab?

And is there a particular mortar/concrete that’s preferred to cover it all back up (after 2 hours)?

Cheers to you and all others for the fantastic advice!

 

[Reach4]

Looks good to me. If the vertical distance is right, there is a 4x3 closet elbow with a 4 inch spigot rather than a hub. That could accept a Push-Tite 887-GPM OR 887-GAM 4" inside fit gasket with SS swivel ring, flush to floor. No glue, although by this time, you will have become an expert on gluing, I expect.

If you could leave space around the riser, you could also use one of the cast iron code blue closet flanges. They are outside compression. They even have a version with a 1 inch offset, in case you need some fine tuning for the position. The Push-tite 889-GPOM gives 1.5 inch offset and has a stainless steel ring.

 

[Girafdaniels]

Looks good to me. If the vertical distance is right, there is a 4x3 closet elbow with a 4 inch spigot rather than a hub. That could accept a Push-Tite 887-GPM OR 887-GAM 4" inside fit gasket with SS swivel ring, flush to floor. No glue, although by this time, you will have become an expert on gluing, I expect.

Great to hear, thanks!

I actually rolled up the 2” inlet a little more after this pic, which still gives me about 1 1/4” to pour above the elbow at the wall.

The top of my 90 for the toilet is currently 3/4” below the top of slab, so I’d have to check on that 4x3 closet elbow. Appreciate the thought. If it doesn’t work, is there anything else I should consider to make everything as easy as possible for the toilet install? I’ll have to add about 3/8” self leveling cement for the broader area after filling in my hole, btw...

 

[wwhitney]

I suggest rolling up the wye as far as possible while still maintaining 1" concrete cover on the pipe just before the elbow at the wall. [1" seems like it would work to me, depending on the floor covering, but I'm not a concrete expert.] Also, since you have a street 45 and a 22.5 in series on the wye branch inlet, you can play with those angles a little to be sure you get back to 2% slope as quickly as possible. You want all your elevation gain at the wye to be used for rolling the wye, minimizing the amount used by those two angles.

I assume you are going to back fill with clean soil or sand up to the elevation about 4" below the top of slab? You'll want to try to compact the fill, particularly under the pipes, which is one attraction to sand, it's easier to compact. To get the new slab to bond with the old slab, you want to be sure the old edges are rough, not smooth. You could epoxy in rebar stubs or (easier) add half-driven stainless tapcons along the edges for mechanical reinforcement and vertical locking but I'm not sure if that level of care is called for or not. Then you want to add a vapor barrier as was there previously (6 mil plastic is fine). For concrete, I'd suggest something like a 5000 psi bag mix, or maybe a mix with fiber (not sure). The important thing is not to use too much water, bread dough consistency is good.

Looks good, and good luck!

Cheers, Wayne