Two 2" drains or One 3" drain

Hey all,
I'm in the process of building a custom 72"x52" shower that will have essentially two full spa like showers each with a rainhead, body sprays and a handheld shower. It'll be a Delta system so no more than two of the components can be on at once. My question is:

Do I really need two 2" or one 3" drains to cover this?

If so, which is best?

If the two 2" then do I just plumb them in in series or do they have to have separate drains?

If the one 3" will I have to run a full 3" drain line all the way to the main drain line in the house?

If two 2" how do I build a proper pan to slope it correctly?


Many thanks for the help.

quote; If the two 2" then do I just plumb them in in series or do they have to have separate drains?

separate, otherwise you still only have one 2" drain

If the one 3" will I have to run a full 3" drain line all the way to the main drain line in the house?

Yes, because you cannot reduce the drain line in the direction of flow.

If two 2" how do I build a proper pan to slope it correctly?

Build a "ridge" down the center. Put a drain in the middle of each section, and slope to the drains.

Many of the linear drain companies make multiple outlet drains.

You can get these linear drains made with one, two or even three outlets.

Depending on the tile layout and local code you might consider a three inch drain in the shower's center and a separate linear drain at the shower's entry location.

With multiple fixtures you might run into a plumbing inspector who wants see some custom grading. Best to discuss this first and understand his requirements. There are some plumbing codes in relation to shower construction that state you can not have the path of one shower run across that of another.

The tile top point drains from My Shower Grate Shop and LUXE come in 3" versions as well. That is a nice look.

Good Luck with your project - I hope it turns out just like your hoping.

JW

Thanks HJ. That's pretty much what I thought, but I was hoping to be surprised by someone saying, "No, one 2" drain will be fine!" :)

Quote:

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Originally Posted by presidentsdad

Thanks HJ. That's pretty much what I thought, but I was hoping to be surprised by someone saying, "No, one 2" drain will be fine!" :)

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Update: It took me about three hours on a Friday to remove the old and install the new piece from the upstairs to the basement and another 2 hours to cut into and retrofit the new 3" line into the 4" house sewer line. This includes two trips to Home Depot since I didn't know which fittings I'd need! Thanks for the advice!

Presidentsdad when you go next time for a material run like this just buy a wack of fittings and on your next trip back return the un used ones.

Much easier this way.

JW

I did buy a lot of extra fittings, but apparently not enough! :)

Question for the group. I have the 3" waste line run, but now I need to plumb the shower drain. I'll be using a 3" Kerdi Drain. My problem is two fold. There is a floor joist in the center of where the drain should go, so I assume I can just shift it to the left or right to go around the joist. Is that right?

Also, there isn't enough room under the exit to run the drain directly into a trap. Is it OK to go drain, 90, short pipe (like 16"), 90 into the trap, then slope to the drain? The "old" shower I'm replacing had 4 90's before the trap. This would only be 2! :)

Thanks for the help.

Well, I went ahead and plumbed it this weekend. I went with two 90's back to back, down into the trap and sloped over to the waste stack that came up from downstairs.