View Full Version : New cast iron pipe for shower--what drain?

06-11-2007, 06:20 PM
Hi. My basement has new roughed in plumbing for a bathroom, including a shower. I have found lots of options for installing shower kits or doing a mud/liner type tile shower, but most specify abs or pvc for the drain.

I have brand new cast iron pipe. What are my options for a shower drain that connects to cast iron?

Secondly, how much must the cast iron pipe stub up to accept the shower drain?

Ideally, I'd like to use either Kerdi or Tile-redi to build the base, but I may wimp out and want to go with a simple kit or a swanstone base.

I guess I want to know what my options are. That would dictate whether I do the most or least labor-intensive option.

Thanks in advance for your advice.


06-11-2007, 07:42 PM
Take a picture so people can see what you have to work with. The easier thing would be to maybe snap it off, couple it to pvc, and set the drain where you want it. If you go with a Kerdi, you need the last bit to be either abs or pvc. Kerdi does make a bulletproof shower...did one for my mother over Christmas.

06-12-2007, 01:37 PM
Can't find my camera at the moment, but imagine a perfectly smooth new concrete floor with a 2 inch cast iron pipe sticking up about 6 inches.

Simple enough to couple PVC to it, if snapped to the correct height, using a no-hub rubber gasket? What is the correct height?

Also, would coupling pvc to the cast iron also raise my shower up higher?

Or is this an option: http://www.fernco.com/SD.asp
Not sure how if it works with Kerdi, for example.

06-12-2007, 03:02 PM
Best left for one of the pros. Normally, the drain is attached very close to, at, or below the floor (so that the top isn't too high). Unless you dig out some concrete, the shower floor will be quite high with all of the fittings you have to install above the floor to install a clamping drain. A mudbed (if you go that route) is at least 1.25-1.5" above the slab at the drain, but the drains are thicker than that which would make the thing higher. An adapter would add inches at the minimum, to the height, maybe a bunch more than that.

Sometimes they only put a thin coat of cement right around the pipe which you can break up to cut the pipe to an appropriate height.

If not, then you might have to think about breaking up some around that.

How deep is the trap?

06-12-2007, 05:44 PM
Thanks for your help. Breaking up the concrete is not an option. I have radiant tubing in the floor (nice and toasty). It's a brand new floor. It was plumbed this way by a professional plumber specifically for a shower, so I'm guessing this is standard practice.

There must be a shower drain that works with cast iron pipe and allows for a fairly straightforward shower installation.

I'll check with a local plumbing supply and see what they say.

The trap is way down. Probably 10 or 12 inches. But, like I said, the concrete stays. I'll let you know what I find out.

06-13-2007, 09:17 AM
the professional plumber knows for sure what to do in your situation. Call him on his mobile phone.

Whatever sleeve is going to go around the outside of that pipe, will need a little room around the pipe, so you may want to ask the plumber about the space needed, and the spacing of your radiant heating, around the drain pipe. A little wiggle room (not ripping out your heat).

The worst case scenario is that you have to build upwards from here on, and then the floor of you shower ends up a couple inches higher than now. Then, the shower needs a threshold (sill) to hold water in, so you would be stepping over a barrier 5 or 6 inches high onto a floor raised a couple inches or more. That is a real safety hazard, for two reasons that compound each other. First, the two inch height differential, like a half-step that people are not expecting, or can't handle well unless very limber, is dangerous all by itself. Secondly, the sill adds to the barrier psychologically and physically, and makes almost invisible that height difference in the floor levels inside the shower and outside it.

So, it is a good idea to plan on getting the drain down down low into the pipe.

Talk to that plumber about your options.


06-13-2007, 10:01 AM
Neither the plumber nor the concrete people did you any favors...unless there is some space around that pipe, you are then forced to make the shower floor higher than desired or needed. In fact, ideally, they could have depressed that area so the shower floor could have been at the same height as the surrounding. Also, CI is a pain to cut when you don't have any room, such as you could if it was pvc, where you can use an inexpensive, internal cutter to get it the right height.

You need a clamping drain if doing a conventional pvc liner shower construction or to convert to pvc or abs to do a Kerdi shower. A kerdi shower might allow the minimum height buildup because it only requires one sloped layer instead of two for a conventional shower pan, but the conversion to plastic for the drain is the problem. This is where you turn to a pro to really evaluate your best options. The ultimate best option has been taken from you from how they did things to this point.

There may be some preformed pans designed to use a compression drain that would fit over the CI, and then could be cut off, but that would leave the cut edges exposed right beneath the grate...not sure I like that. Some of those pans can be tiled, but personally, I find them kind of cheap, and they don't look that good after awhile. A well done tiled shower can look like new for decades if cared for...that will never happen with a manufactured pan.

06-14-2007, 06:28 AM
Neither the plumber nor the concrete people did you any favors. I'll bet your plumber has never had to face this situation. Even if he tells you about something you can slip inside the 2" CI pipe, that drain device will still have its physical dimensions (height) and it will force the floor to be raised more than necessary.

Starting at the top of the drain, a shower floor gets even higher from that point. The drain has to be the lowest point.

This whole thing has to be thought out before pouring concrete.


06-14-2007, 12:36 PM
Thanks for all your help.
I'm considering a tile-redi pan. They informed me that it is a simple matter of using a rubber connector between the built-in pvc drain and the cast iron pipe and that it would not raise the height of the shower unnecessarily.

Are any of you familiar with the tile-redi pans?

On an un-related topic, anyone have any idea where I can buy a 3" brass flange meant to go over a lead toilet bend? I went to my local plumbing supply and he did not have any in stock, but described exactly what it was and how to install it. I'm starting to think that New York City plumbers do things a little differently than the rest of the country.

06-14-2007, 01:25 PM
From what I hear, you also can get in big trouble if you aren't licensed, but I don't know that for sure; especially if it is a multiple family dwelling and you are a DIY'er.

There probably is a method to connect the CI to the compression fit drain, but I'd worry about the fact that it is rough...I know it works with pvc. Also, seems like the wall thickness on CI varies some from brand to brand, and I'd be worried about that as well.

06-14-2007, 02:28 PM
Thanks for all your help. So, I've been studying this mud-bed thing and I'm pretty good with tile and concrete, so I'm thinking I don't need to resort to any pre-fab, but can do my own shower pan with a pvc liner.

And I'm listening to you guys about being able to get to the drain pipe a little better. Perhaps some careful chipping around the shower pipe will not be such a big deal. It seems like that is the best route, no? How much of it do I have to expose?

Connecting the bottom portion of the drain to the cast iron--fernco coupling? Or is there some kind of direct to cast iron drain? The plumbing store showed me the drain with a rubber compression fitting that you turn to tighten to the pipe. I guess that's what you were referring to, jadnashua, and your concern about the roughness of the pipe. Is one approach better than the other? I'm guessing the no-hub is the best approach? So, a 2 inch minimum coupling to the bottom of the drain? Tell me if I'm wrong.

As for talking to the plumber who did the work...I can't. I had a dispute with them when they instructed the concrete guys to pour over the access plate on a backflow preventer valve. My valve is now buried and inaccessible. So, licensed or not, I'm not calling them again.

Thanks for all your help. It's all starting to make sense to me now.

06-14-2007, 05:31 PM
my input here now is both good and bad news.

well, i wasn't there, but I think No matter how angry you were back then, the plumber has to at least answer your questions. He is a licensed Master Plumber, and his profesionnal accreditation and licensing body has a serious enforcement arm that sends people down his back if he doesn't do what he ought to do -- so his doing things wrong twice is now working a little in your favor, because at least you'll get some answers -- I am assuming you either paid him in full or are intending to. i think you can start looking at his licensing body's web site. If you decide to leave him alone entirely, well then start chipping away around the pipe and look for those radiant heat pipes.

as for tile-redi, i think you are far better off NOT listening to them.


06-15-2007, 07:37 AM
I think that the guys over at www.johnbridge.com (http://www.johnbridge.com) probably will have more suggestions. I would hope that the nearest radiant tubing is not right up against the pipe, so you may be able to do something there. Many plumbers seem to want to put the liner directly on the floor, then expect the porous sloped mudbed which will allow moisture to pass through it to magically hold all of it back or flow it to the drain, but any that doesn't, ends up sitting on a flat surface. Your understanding of needing the preslope is good. If you can get a Kerdi drain installed, that's the only slope you need. If you go with a conventional liner, you need to be at least another 1" higher - the final tiling layer above the preslope. This would allow you to keep it as low as possible. Same idea with Wedi, the tileable layer is sloped, so only one layer. A mudbed is the least expensive and the most customizable, but needs to be thicker.

06-15-2007, 08:03 AM
On a slab, using cement ("mud?") is the thinnest option. The other options are the pre-made pans; they are thicker.

Here is how a mud bed is thin, when on a slab. You use the kind of cement product that builds as little height as possible, bonding directly to the existing cement in the slab, and using the slab itself for its structural strength. It starts with feather thin cement around the drain, and it builds a slope up 1/4" per foot up to the height you need. No-one can get any thinner than that.

It's not a pan made of cement product designed to hold itself together or to have any strength of its own That would be a sand mix or deck mud mix, and that would be necessary on a wood subfloor. Not on a slab, not on a slab.

Say "no" to deck mud on a slab.:)


06-15-2007, 09:33 AM
Over a slab, the deckmud needs barely any thickness at the drain. The Kerdi pan is only about 1/2" thick at that point as well. With a traditional liner, your top layer still needs to be around 1" or so regardless of what is under it. With a Kerdi system, the liner is your tileable layer, so regardless of the preslope, it will end up thinner than a traditional system when your drain is at the same starting point. The first layer, pre-slope can be something other than deck mud, but is harder to shape.

06-17-2007, 11:23 AM
Thanks guys. Very helpful. I'll let you know how it works out.

06-18-2007, 01:05 PM
Here's pics of my morning spent chipping away concrete.

I gained about 2" by removing the concrete, provided I can actually cut the cast iron below the slab level--any recommendations? First I'm going to try accessing the no-hub gasket. It is down there somewhere, below the vapor barrier and the pink styrofoam insulation. Provided I can get to it and get a screwdriver to it, that would be the easiest thing.

So, the recommendation is to use a Kerdi drain? It seems that would be the lowest height option? I would either use deck mud or something else for the pre-slope. The drain looks like it costs about $120. Is it best to buy the waterproof membrane in a roll or buy a shower kit? Any advice on that? I'm just making a 36" square shower with two tiled walls.

Thanks again, this is turning out better than I expected.


06-18-2007, 03:04 PM
Check out www.johnbridge.com (http://www.johnbridge.com) and look at their on-line store to check on prices. If you are going to use Kerdi, you need the system. That, at the minimum is the membrane and the drain. You don't need their preformed pan (you could cut the 4' square one down), as you can make your own cheaper, but not faster! Same is true with their pre-formed curb...you can make your own. Do it with 2x4's, cover with drywall, then Kerdi. But, the preformed curb is faster. You pay for the speed.

John's site also has drawings on the drain, so you can view the shape. It will also give you an idea how low you should go to make the connection, or conversely, how high your floor will need to be.

I do not know if you could do a leaded clampiong drain. Not sure if they even make them. If they do, you might go with a conventional construction.

Anyone know if there is a leaded clamping shower drain available?

06-18-2007, 03:12 PM
looks good. drains come in many varieties, so check them all out. There are many roll-on trowel-on paint-on membranes, so don't limit yourself to the Kerdi option. Its drain has a particular shape.

... provided I can actually cut the cast iron below the slab level ... I'm going to try accessing the no-hub gasket. It is down there somewhere, below the vapor barrier and the pink styrofoam insulation. Can you explain more about this?


06-18-2007, 03:51 PM
This slab was recently poured over a vapor barrier and 1" polystyrene insulation. On top of that is mesh reinforcement. There are 3/8" pex radiant tubes in the floor, attached to the wire mesh with cable ties.

Luckily the tubes are not in the immediate vicinity of the pipe, but I wasn't certain of that when I started.

I cut out the 1" of foam, so now I have one more inch of depth around the pipe. I don't think I can get to where the rubber no-hub coupling is. I'm guessing it is down another foot or so, since the water in the trap is about 8-10" below the top of the slab.

The big question is how to cut that cast iron pipe? I can't go any wider on the hole I dug without tempting fate and risking bursting a pex tube. Is there an inside cutter for cast iron?

Standard practice around here is the pvc membrane. I'll look into the paint on kind. Does it work well? This is going to have to be an extremely permanent installation since I won't be getting to that shower pipe again after it's installed and re-buried in mortar.

06-18-2007, 03:57 PM
Latticrete makes a trowel on sealant/fabric system. I think the Kerdi is easier. You can watch a video of them installing Kerdi at www.schluter.com (http://www.schluter.com). As mentioned earlier, Wedi stuff is neat, too, and it adds insulation, which can be a bonus in a basement. WIth Wedi, you could start in the morning and have the tile on by evening if you are good at tiling. You'll be longer if you need to make your preslope yourself.

06-18-2007, 04:22 PM
Thanks. Um, my original question on this thread was how to connect a shower drain to a cast iron pipe. Everyone said I had to switch to plastic (at least I think that's what I was told). I just looked at Zurn.com and saw two cast iron shower drains that seem to have a "no hub" option.

Model FD2252 and Model FD2254

On JohnBridge, there was an old thread about a "jiffy gasket" or some such thing that slips over the cast iron pipe to seal the shower drain on.

So, if anyone here knows, I'll return to a variation on my original question...how do these cast iron drains attach to the cast iron pipe? Do they all use the gasket described on JohnBridge?

And thanks, I have watched the Kerdi videos, etc. But if I don't have to use a plastic drain, I think I'd rather not.

It's also okay if you all don't know the answers to my questions. I will go back to the plumbing supply place (the same ones who were able to tell me in great detail how to weld a brass flange onto a lead toilet bend and order the correct one for me). It's just that it's after 6 and they are closed now.

I will document all of these things and post here for future people like me who may be confused by the seemingly arcane NYC plumbing practices. We are so old school here.

06-18-2007, 06:48 PM
There's a distinct advantage of using something like Kerdi or Wedi - there's almost nothing to absorb and hold moisture. In a conventional shower, you have an inch or more of deck mud on the floor and 1/2" cbu on the walls. With the Kerdi or Wedi, all you have is the tile - it dries out faster, and is less likely to harbor mold in the end. Plus, the whole thing is basically waterproof.

06-18-2007, 08:24 PM
I have brand new cast iron pipe. What are my options for a shower drain that connects to cast iron?
Hire a plumber

Secondly, how much must the cast iron pipe stub up to accept the shower drain?
Hire a plumber

I guess I want to know what my options are. That would dictate whether I do the most or least labor-intensive option.
Hire a plumber

Thanks in advance for your advice.

Your welcome

06-18-2007, 08:31 PM
a plumber already is involved.

06-18-2007, 09:36 PM
... going to have to be an extremely permanent installation ...

brass, no-caulk, removable drain. See http://www.terrylove.com/forums/showthread.php?t=11157&highlight=oatey and take it from there.


06-18-2007, 09:48 PM
... how to connect a shower drain to a cast iron pipe. Everyone said I had to switch to plastic .... "jiffy gasket" or some such thing that slips over the cast iron pipe to seal the shower drain on. ....
It's also okay if you all don't know the answers to my questions. ...always a good idea to restate the original question from time to time. Personally, I don't know the answer, and I don't want to go websearching. Keywords are drain (floor or shower) and CI for Cast Iron. I just did one quick search, using --- CI brass drain "2"" --- as keywords, and I saw Zurn drains. I don't know much about them. They looked like they were all clamping drains, and that would need the PVC liner.