Shower drain [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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09-05-2001, 08:03 AM
I am replacing my shower pan and have a question on how the drain connects to the cast iron flange in the slab. I have removed the shower floor (tile & bed). I now have the drain exposed and it looks to be connected to a cast iron flange embedded in the concrete slab. I know the new membrane must go between this flange and the drain flange. My question is how do I remove this drain flange? It appears to be connected by 3 bolts. These bolts have corroded and don't look like they will come out. I will have to cut the heads off to remove the drain flange. Do these bolts thread into the flange or are there nuts on the under side of the flange in the concrete slab.? If they are nuts on the under side of the flange ,do you have any advice on how to connect the new drain flange. And if they are thread into the cast iron flange, can they be drilled and re-tapped?
Thanks for any advice you can give.

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Bud Cline
09-05-2001, 10:11 AM

If you are sure this "three bolt flange" is at subfloor level then you got big trouble. That appears to be the correct floor drain but was originally installed improperly.

If your floor is flat then that is more than likely the cause of your shower failure.

If I'm understand what you have there then I would say start jackhammering the concrete to remove the existing flange and start over. We can get you thru this procedure and all that follows.

There are no nuts below the flange. The bolts thread into the flange. To drill and re-tap the existing flange won't work because the flange is in the wrong place to begin with (wrong elevation).

What do you think?

09-05-2001, 10:30 AM
Thanks for the reply, Yes the flange is at the sub floor level. It does not stick up above the slab. Sound like I'm in for some fun! I did not want to hear that I had to break up the floor, but if that's the only way. You says this was not installed correctly is it suposed to be above slab grade? If so how high? Once I remove the concret from around the flange can I use a fernco connector and just add a new piece with a new flange. I plan on gettting a book to show me how to install a shower pan and they may go into to that but just thought I'd ask. One other question can I use PVC for the new flange?
Thanks again.

Bud Cline
09-05-2001, 10:41 AM

Before I get my head pounded here.....I guess it is conceivable you could leave things as is and pour a slope to the flange where it exists. Problem is if you can't successfully remove the bolts and are talking of the need to drill and retap, then taking the thing out to start over I think is by far the lessor of the evils.

I would want that bottom flange about an inch above the existing subfloor. You could then reinstall a sloping concrete primary shower floor and fill the hole you are going to create at the same time. This new concrete would come up to the surface of the flange (probably as it is now) and gradually slope "up" towards the walls.

And yes a plastic PVC shower floor drain (flange type) is acceptable.

John Bridge
09-05-2001, 04:15 PM

I'm not sure you have removed the entire mortar bed.

I'm not sure I know what's going on at all here, but if the lower flange is at or near the subfloor level, I think you can slope up from there for the new pan. You simply bond the new mortar to the slab -- feather is from the drain flange upwards to about 3/4 in. at the walls.

Try a visegrips on the bolts. If you break the heads off you haven't lost anything. Hey, they might come loose.

Is there any way you could email us a pic?

Rob Z
09-05-2001, 08:35 PM

A pic would be a big help. John can talk you through the computerese of how to do it. Bud and I will tell you how to tear stuff out.


09-06-2001, 11:56 AM
Hello folks,
Yes, I will take a picture tonight. I have not done any more with this, working at my real job right now. My concern is if I break the blots trying to remove the drain flange. By drain flange I mean the upper piece that has the strainer screwed to it. If these blots break off and I can't extract them from the drain assembly (lower flange), will I have to remove the drain assembly or is there a way to connect the new drain flange and seal the membrane? If I am still am not making sense we can wait for the picture


Bud Cline
09-06-2001, 05:26 PM
It is imperative that you have all three of the threaded holes in the lower drain flange available. This is needed to properly clamp your vinyl pan liner.

Which is why I said earlier; take it all out and start over if the bolts snap off.

Manny M
09-09-2001, 02:33 AM
for the bolts I think before trying to extract them you have to spray them with WD40 and wait until the WD40 penetrates I know that a drop of brake fluid will work better

John Bridge
09-09-2001, 08:41 AM
Way to go, Manny. Good old WD. Don't get caught without it.

Kirk Downey
09-15-2001, 01:20 AM
Sometimes letting the WD40 or brake fluid soak-in overnight is a good idea too. Particularly if you've got one bite at the apple to avoid a big costly hassle.