Connecting Kerdi drain to cast iron drain pipe

[hopkibm]

I have torn out my old shower which had a lead pan. I plan to use the Kerdi membrane to replace the pan and build a mud pan (the shower floor is 48 x 32 and the drain is not in the center). My old drain/screen was bolted to a cast iron flange. What's the approved method for attaching the Kerdi drain to the cast iron?

[ddmoit]

Welcome to the forum, Hop. How about a first name we can call you?

You might want to consider replacing that cast iron past the P-trap, and perhaps all the way to the sewer line. You can replace it with PVC or ABS, whichever is suited for your locale. You can use a Fernco connector at the sewer line, and then your Kerdi drain then becomes a standard installation. Plus, you'll have the peace of mind that comes with a new drain line.

[hopkibm]

Call me Max. Hop was my dad.

Forgot to mention that I have a slab floor, so replacing cast iron to sewer line would be major, major issue, not willing to go there.

[Brian in San Diego]

Max,

Sorry, but I think you're going to have to "go there". There is no effective way of attaching a kerdi drain to the portion of the drain that you have showing. In fact, if you were doing a conventional shower, you'd have to bust out the concrete to replace the drain. If you do a search on replacing drains, you may find some insight. It isn't as hard as you may think and the only way to get the job done right. And besides, there's something special about a chipping hammer and concrete on a Saturday morning.

Brian

[Mike2]

Max, I agree. One way or another you'll have to chip up some concrete, remove that cast iron flange and convert to plastic. So it's really a matter of where to make that transition. This might be one of those 4th of July's you'll remember, for a long time.

[hopkibm]

OK, OK, you guys win....I'll do my best to start bustin' concrete. Calling a plumber to give me an estimate on the cast iron cut and replace. Do I backfill with sand and then pour concrete back in the area that I busted out? In doing this, I could then center the drain hole and possible use the Kerdi shower tray. If my fingers still work and the blisters aren't too bad, I'll report back in a few....later....

[Brian in San Diego]

Max,

If you don't feel comfortable cutting the cast iron and installing the drain, then by all means call a plumber. I think that part of the job is easier than the busting out part. Cast iron can be cut by a number of methods. I would assume that most plumbers use a soil pipe cutter. You should be able to rent one from a local rental yard. It looks a little like a chain wrench, but it has cutting wheels on it. There is a ratcheting type that can be used in tight places. Once the pipe is cut you could install a Fernco fitting (available at HD and Lowes) and run you PVC from there. It's not difficult and between here and TerryLove.com you should be able to handle it. The pipe can also be scored with a metal wheel on a 4" grinder and then struck with a cold chisel. Someone here said they cut theirs with a heavy duty metal blade in a sawzall. Whatever you decide, all the best. I think you'll find the chipping part to be easier than you think.

Brian

[hopkibm]

Yeee Hawwww I got the concrete busted out. Got a new chisel from Lowe's and after about an hour, had half a 5 gallon bucket full of concrete right around the drain. Lost about 5 pounds in sweat, started to get a blister, so headed off to tool rental. Brought back a 20 pound electric jack hammer and in 1/2 hour hand a good sized area busted out. Well worth the $50 rental. Dug out a bucket of dirt around the main sewer line, so now I'm read to tackle cutting the 2" drain pipe going down into the main line.

Just to be sure, I'll need a 2" PVC or ABS to connect to the Kerdi drain, correct?

Guess I'll need to make a mud pan since my shower is 48" X 32". Can't think of any way to cut the Kerdi pan "equally" with those dimensions.

Once I get the drain done, I'll get all my plumbing completed. Wife wants the rainshower head, a hand held hose, and a couple of those jets....sounds like a lot of spraying to me, but after 34 years, I've learned to say "OK, let me see what it'll take." Usually have to wind up buying some new tools to get all her "wants" taken care of, so that's my definition of a "win/win". Later..thanks for the support!!

[Brian in San Diego]

Max,

When you get a chance would you go to the User CP tab in the dark blue toolbar above and put you name in your signature line?

Yes, you want either 2" ABS or PVC for the drain connection. Here on the Left Coast about all you find in the big boxes is ABS. They'll have PVC for sprinklers and such, but won't have the correct fittings so waste drains. Either works and remember to specify when you order your kerdi drain.

Brian

[hopkibm]

Thanks for the info. I'll get to the plumbing supply this week and get things moving. Will report back after more progress.

Sorry about the signature miss on my part. Think I have it there now.

[hopkibm]

OK, somebody give me some help here. I thought I would cut the 2" cast iron pipe and put in a PVC P trap. However, looks like the pipe is leaded into some type of flange that goes to the main sewer line. If that's the case, can I just cut the cast iron and connect a straight piece of pvc, put the dirt back in with a vapor barrier and then pour in some concrete? Having some trouble attaching a pic of the drain and line. Will get my daughter to help me post it.

[Mike2]

If that's the case, can I just cut the cast iron and connect a straight piece of pvc, put the dirt back in with a vapor barrier and then pour in some concrete?

Yes, you've got it.

Max, suggest you pick up a cast iron pipe snap cutter at your nearby rental shop. Here's what they look like.

[hopkibm]

Ok, got more powerful computer...kids have all the good stuff....but, the file is bigger than the limits. Oh well. I guess I'm at the point whatever was plumbed in cast iron, even though it's not a P trap like I've seen, I can just attach the PVC to it and get moving. Any comments/suggestions?

[hopkibm]

Thanks Mike. I'm taking off work tomorrow to get this project moving. I'll head to the rental place first thing. 'preciate it!!!

[Mike2]