Will PVC pipe crack my mud bed?

[amark16]

I'm just finished assembling and joining my PVC drain pipes for a linear drain installation.
I'm now prepping for my single slope mud bed, and was planning on burying the PVC pipe in it. The thickness of the mud will be 12cm on the high side, descending to 9cm at the drain. One potential issue I see now is that there will be a relatively thin layer of mud on top of the PVC pipe after the mud bed is finished, and I'm worried that this weak spot might cause a crack. By thin I mean around 3/4 inch.
As a DYIer I'm trying to come up with perhaps non-standard solutions so bear with me, but here are some thoughts:

1. If I pack the mud really tightly around the pipe, and perhaps rest the pipes on something something to minimize downward flexing, will this be enough?
2. If not, I thought of making a regular wet mortar mix and pour over the entire are to cover up to the top of the pipe. After it cures, place a layer of plywood on top, and then build my sloped mud bed. The mud will still be quite thin at the drain end, but this way, I'll decouple the mud bed from the pipe by use of the plywood, so that any cracks below will not transfer to the dry pack.
3. Also, are there any issues with burying the pipes in either wet or dry mortar? Do they need some protection in the form of a sleeve?

Am I overthinking, or am I right to try and address this week point?

Here are some illustrations to assist.

 

[breplum]

You required to have a P-trap directly under the drain itself. So that is the first thing. Foul smells and methane gas develop in drainage piping and you have no protection there !
Pipes embedded in a slab must have protective foam wrap to isolate the pipe from direct contact and allow for expansion/contraction.

 

[amark16]

You required to have a P-trap directly under the drain itself. So that is the first thing. Foul smells and methane gas develop in drainage piping and you have no protection there !
Pipes embedded in a slab must have protective foam wrap to isolate the pipe from direct contact and allow for expansion/contraction.

Thanks for the reply. The trap is integrated in the linear drain. There is a plastic oval cover that goes over the central hole there and this traps the water there. So a p-trap would cause double trapping I believe. Thanks for the tip on the protective foam wrap. Any comments regarding my worry of a weak spot in the mud bed directly over the drain pipe?

 

[breplum]

I can't make a wise comment re pipe in the mud bed. Please share who that drain mfr is. I have not seen integral trap in a linear drain before but I like that support setup.

 

[amark16]

I can't make a wise comment re pipe in the mud bed. Please share who that drain mfr is. I have not seen integral trap in a linear drain before but I like that support setup.

I can't make a wise comment re pipe in the mud bed. Please share who that drain mfr is. I have not seen integral trap in a linear drain before but I like that support setup.

The drain is from a Greek company (tema.gr). It's nothing fancy really, made almost entirely of PVC and quite cheap. I had a builder friend look at it and he is the one who pointed out that if I connected to existing P-trap that would lead to double trapping.

 

[breplum]

I seriously don't see from the profile of that drain that there is a water seal. A water seal needs a few inches of liquid to work.

 

[amark16]

I seriously don't see from the profile of that drain that there is a water seal. A water seal needs a few inches of liquid to work.

Here are a couple more photos to hopefully illustrate better. With the top cover in place, there is always a water seal there.

 

[breplum]

Cool ! Makes sense to me now.
Does that drain have a UPC approval stamp?

 

[Ludington]

Here are a couple more photos to hopefully illustrate better. With the top cover in place, there is always a water seal there.

Until it dries out..doesn't look like much water to leave behind, and may accumulate scum very easily. looks like you will always see water in that bowl, like a toilet. Or am I missing something. Sorry to be so negative.

 

[amark16]

Thanks Ludington. No worries, I want to hear any opinions, positive or negative. Maybe the photos don't show it well but it holds enough water not to dry out with daily use. Regarding scum and hair, yes that could be an issue. I guess we'll have to clean it regularly.
I would appreciate any thoughts on my primary issue which is the possibility of a mud bed crack right above the pvc pipe. I've seen a lot of linear drains with a horizontal drain so I'm guessing this is something common that i shouldn't worry about?

 

[MicEd69]

I share Ludington's concern, and those expressed by breplum. The depth of the trap integral with this fixture seems quite shallow. Depending on your downstream piping and fixtures, I can see possible problems.

Are you in the USA? If so, that drain should have some plumbing association approval before I would install it. Daily usage should keep the trap wet, but you have a lot of surface area that will assist in evaporation. And if you live in Arizona, I wouldn't go on vacation. LOL.

And to answer your question about the concrete, yes it will crack. The two things about concrete are that it gets hard, and it cracks at the weakest point. If the elevation would allow, I would add a 45 to the integral 90 on that drain to get the pipe lower in the bed. If not, your likely structurally fine. Just make sure your rock base is well compacted and perhaps use some Concrete Countertop Reinforcement Mesh, like SpiderLath Countertop Fiberglass Lath in your mud base. Use a good membrane and you should be good.

 

[amark16]

I share Ludington's concern, and those expressed by breplum. The depth of the trap integral with this fixture seems quite shallow. Depending on your downstream piping and fixtures, I can see possible problems.

Are you in the USA? If so, that drain should have some plumbing association approval before I would install it. Daily usage should keep the trap wet, but you have a lot of surface area that will assist in evaporation. And if you live in Arizona, I wouldn't go on vacation. LOL.

And to answer your question about the concrete, yes it will crack. The two things about concrete are that it gets hard, and it cracks at the weakest point. If the elevation would allow, I would add a 45 to the integral 90 on that drain to get the pipe lower in the bed. If not, your likely structurally fine. Just make sure your rock base is well compacted and perhaps use some Concrete Countertop Reinforcement Mesh, like SpiderLath Countertop Fiberglass Lath in your mud base. Use a good membrane and you should be good.

Thanks MicEd69, some good pointers there.
I don't live in the US, I'm in a small European country and there is no plumbing code here or any approvals or inspections needed for a renovation project. So it's up to me as the homeowner to follow good plumbing practices as far as reasonably possible.
Regarding the drain, I forgot to mention that it has a cosmetic stainless steel face that goes on top so there will be very little to no surface area exposed to evaporation. I'm uploading a video to hopefully better illustrate the amount of water that is trapped.
The idea regarding the 45 angle coming out of the integral 90 does make sense and it did cross my mind, but unfortunately elevation does not allow it. So I'm pretty committed to what I have installed now. I do like the idea of the fiberglass mesh though and I do have some left over. Will I have to place it near the very top face of the mud bed?
I have also thought about the possibility of instead making a dry pack, to use regular wet mortar, in the hope that it will be stronger, but that's perhaps a misconception in my mind.

 

[turdchaser2000]

Thanks for the reply. The trap is integrated in the linear drain. There is a plastic oval cover that goes over the central hole there and this traps the water there. So a p-trap would cause double trapping I believe. Thanks for the tip on the protective foam wrap. Any comments regarding my worry of a weak spot in the mud bed directly over the drain pipe?

Looks like a bell trap which is prohibited by most plumbing codes.


You might try a crack isolation membrane or an uncoupling membrane between the mortar and tile

 

[MicEd69]

Thanks MicEd69, some good pointers there.
I don't live in the US, I'm in a small European country and there is no plumbing code here or any approvals or inspections needed for a renovation project. So it's up to me as the homeowner to follow good plumbing practices as far as reasonably possible.
Regarding the drain, I forgot to mention that it has a cosmetic stainless steel face that goes on top so there will be very little to no surface area exposed to evaporation. I'm uploading a video to hopefully better illustrate the amount of water that is trapped.
The idea regarding the 45 angle coming out of the integral 90 does make sense and it did cross my mind, but unfortunately elevation does not allow it. So I'm pretty committed to what I have installed now. I do like the idea of the fiberglass mesh though and I do have some left over. Will I have to place it near the very top face of the mud bed?
I have also thought about the possibility of instead making a dry pack, to use regular wet mortar, in the hope that it will be stronger, but that's perhaps a misconception in my mind.

OK, it looks interesting design and workable, although not per any USA code. I think I would just use regular mix with the fiberglass reinforcing.