Replacing/reusing an old shower drain in slab-on-grade floor?

6 years ago

I've demo'd our small master bath to the studs, and am in the early stages of a complete remodel that i'll be doing entirely on my own. So far I've found only one item that I'm unable to locate a solution for, either online or in the various books I have on hand. Our house is a 1956 slab-on-grade construction ranch in southern California. The shower drain is original, and is 1 1/2 inch iron, Here's a picture. it's pretty bad.

My assumption is that i'll be busting this out of the floor and replacing it and some of the pipe (to the P-trap? past it?) with 2-inch plastic. This thing was reduced to a less-than 3/4 inch opening when I first got down to it, it was so caked with debris from over the years. I'll be building a pretty simple shower in this bath; no need to re-locate the drain, and just a standard mortared-in pre-slope and tile floor with tile walls.

I've been able to find endless information on 3-piece shower drains, and how to install them in wood floors. I've been able to find very little information on how to deal with old slab-on-grade shower drains. Can this be re-used? Is there some sort of shower drain product specifically for replacing old shower drains in slabs? I'm not opposed to just busting this out and replacing it. I have the tools and the know-how. The vent isn't far from the drain, and I'd go all the way to that junction with new pipe if it made sense, but there's a lot of work to do on this project, and I'm not looking to make more work for myself needlessly.

Thanks in advance for your help,

Chris

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Chris D
Original Author

6 years ago

Thank you! The Fernco no-hub couplings are literally the only solution to this issue I've been able to find at all. Without doing much research on it, I kind of passed the idea by assuming that burying something held together with hose clamps under the slab was a no-no. Glad to hear that it's an option, and that professional plumbers use them. I'll look into it when i get the concrete broken away and see what I have in there. Looking at it again yesterday, I don't think that re-using that existing flange is an option. It looks like the pipe was broken off in an earlier remodel, and the flange somehow fixed around the OD of the iron pipe. In any event, I can't see how I could attach to it now, at least not without reducing the ID of the drain, which is already small.

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Comments (9)

klem1
6 years ago
Look at "NO-HUB couplings" and it will be self explainatory. That will alow you to easily replace as little or as much pipe as you want. Some will ya-da yaa about code but I can tell you I've watched plumbers use then under slabs dozens of times.
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klem1
6 years ago
It look's like the flange to pipe connection was done with lead which was the standard for cast iron. Lead is not a diy thing and you would have a hard time finding a plumber today with tools and knowledge. If pipe is in good condition,there are flanges available with rubber where lead is now. If you go with no-hub,use the best stainless steel bands available,not junk from big box.
Vith
6 years ago
Yea id bust it out and replace the trap as well. Connect to existing pipe with the fernco. These fittings dont need to be accessible, so no worries there. You are right this is literally the only way to connect to cast these days. The only other way is with a cast piece with a hub and using oakum and lead but not common and a lot more time consuming. The time you would waste with hub and lead would cost more than just getting the fernco.
Chris D
Original Author
6 years ago
Thanks, all, for your replies. I think I have what I need to proceed. Incidentally, I just finished reading about how much skill it takes to make those lead and oakum joints on this page. It's a very interesting read!

Thanks again,

Chris
Bruce in Northern Virginia
6 years ago
When you look at no-hub couplings, (e.g. Fernco brand), if you bury it you will need to use one of the couplings that has a metal collar around the rubber. This is the type you want. https://www.fernco.com/plumbing/shielded-couplings/5000-series-rc-couplings

The reason for the metal collar is to provide stability/rigidity to the connection when you bury it under the concrete. If you only had the rubber collar there would be no support and the connection may sag or pull away from the weight of the dirt and/or concrete.

I have also seen recommendations to use the proper coupling, and then also pour a small cement area under the coupling to provide additional support. However, supporting with concrete seems to be more of a preference than a requirement.

Bruce
klem1
6 years ago
Supporting with concrete seems more of a mistake,incase the joint in sand so that movement can defuse over a larger expanse.
Vith
6 years ago
cement as support is overkill, normally gravel is used to help with getting correct slope and supporting
klem1
6 years ago
"cement as support is overkill, "

Some might call it overkill,others might call it stupid if they need to work on the pipe later. That's how the saying "you can't fix stupid" origionated.

Replacing/reusing an old shower drain in slab-on-grade floor?

Chris D
Original Author

Comments (9)

klem1

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Replacing/reusing an old shower drain in slab-on-grade floor?

Chris DOriginal Author

Comments (9)

klem1

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klem1

Vith

Chris DOriginal Author

Bruce in Northern Virginia

klem1

Vith

klem1

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Chris D
Original Author

Chris D
Original Author