Cast Iron to PVC Shower Drain Fitting

[Stacy7]

Hi All,
I am so thankful for this gathering of folks with such great information, and now I hope someone can help me. I've ripped out the old shower that I used only a few times (5 years of sitting idle) to discover a hole in the concrete foundation about 14" x 20" around the drain. It was filled with dirt and rock, which I've dug out to a depth of 18" to inspect the cast iron and pvc connection. It looks very secure. The 2" pvc is pushed down about 4.5" into the cast iron piece and seems secure in a tight black rubber gasket. This leaves me with the 18" of hole to fill. I'm putting in a Swanstone Solid Surface 36"x36" double threshold. So... does the fitting sound okay? I poured water in and it doesn't leak. Albeit, cold water. And, how much clearance of dirt should I leave to pour concrete? I'm thinking about 4". Don't know if it matters, but I intend to install the shower base on a bed of concrete, as recommended. Oh yeah, I know that I need to leave clearance around the pvc up to 6" for the Swanstone drain fitting. Any suggestions on how to do this would be helpful.
Thanks for any advice!
Stacy

 

[Construct30]

I like to make a square hole, box 10" x 10", with concrete, about 4" deep with a concrete bottom. Make sure to leave enough room, depth, for your drain fitting. Concrete should be 3 1/2" thick if possible.

Most fiberglass or acrylic showers and tubs are designed with solid bottoms with OSB plywood these days. They don't recommend putting solid concrete under them like they used to when they were just fiberglass swanstone counters are blobss of silicone not solid. They want you to shim in certain areas onto a suitable strong floor. I would check with the manufacturer about using concrete under the entire thing unless it came with clear installation instructions. If it did then follow them. Usuall they want shims under the feet and some around the drain. You can shim with concrete blobs, latex modified or it will break up, or treated wood and a glue that is OK to use on foamboard and fiberglass, be careful of the glue be sure it won't eat the fiberglass. You do need access to both ends to use glue and shims or you will have to mark the feet and use the concrete bloobs. It is hard to get the shower level and get good contact patches when you put the concrete down first then put the shower bottom over the drain and press it down, if you get it to low you have to lift and put down more concrete. I hope you have access to do it after. It is like trying to level a giant fragile block, if you get it low you have to lift and reapply the mortar.

go to www.swanstone.com and read their installation instructions and do the best you can.

good luck

 

[Sponsor]

 

[Construct30]

By the way, don't use a glue drain fitting, use a rubber gasket type. Leave it high out of the floor and cut it off after the install with a dremel type cutter from inside the pipe, go easy with that. It is impossible to get a glue type drain the right height in a concrete application. Alignment and level is critical, make sure the pipe is level and plumb coming up out of the concrete. Swanstone is tougher, because of the weight and cracking. We've always used silicone or their glue for counter tops. I heard it can wick some mortars or concrete. Does the bottom have a protective layer on a shower for a mortar bed? On the counters they want the bloobs of glue so I would assume a base would be the same for level.

 

[Construct30]

Notice that they say to use silicone on the drain not oil base putties. They say latex based quikcrete for shimming bed under the feet.

 

[Construct30]

I did notice your model has a built in drain, does it have the rubber gasket in it? The retrofit model does. I hope yours does and not a glue type.

BTW setting the base is at least a two person operation when you know what you are doing. I hope you have helpful friends or family. Plan out the install and don't rush it, be careful of the drain. I have taken the rubber gasket out, set the shower and used liquid soap on the inside and outside of the gasket and slipped it in after. I like to use some clear 100% silicone around the top of the gasket, after I get the soap off. Have a blunt, plastic tool to help press the gasket into its home.

 

[Stacy7]

Hi,
Yes it does have a rubber gasket in it. Thanks for the tip on removal and "slipping" it back in.

Is a 6" or larger pvc placed over the 2" drain an acceptable way to go? That seems like a method of keeping the clearance.

Are you suggesting that the subfloor it sits on should be plywood, and not concrete? The enclosed and internet instructions are sparse.

Thanks for all of your help, wish you were here to help with the install!
Stacy

 

[Stacy7]

Pic of fitting and hole

Here's a photo of what I'm up against. Thanks for your help.

 

[Construct30]

The concrete is good, a fiberglass shower has the plywood molded into it. A good concrete floor is a great base. I've only installed one such base. I laid cerenic for the walls so I didn;t install the walls. I've put in many fiberglass units, and the installation is similiar.

In my opinion I would make a little bigger hole than the six inch pipe would allow. Don't make things too tight, if you are off a little you will be chopping concrete. The drain is not the ideal, but in some cases you have to work with what you have. Water going down is not the only issue, you have sewer gas coming back up. If it has a tight rubber gasket in it you should be fine, clean it and also put some 100% silicone around it to help the seal. The ideal would be to stick a test ball down it and seal the pipe so it could be water or air tested. I've seen a lot worse, use the silicone and maybe put some latex modified concrete around it. Fill the hole to within eight inches of the floor level with small gravel or limestone, dump four inches of high strength concrete into the hole center your form and put more concrete around the form. Be very sure the pipe is level and plumb or it will be imposible to get the rubber gasket over it into the shower drain. Let that get hard before you remove the form if it is wood, if you think the six inch pipe is big enough go for it.

Is that pipe in exactly the right location for the shower or are you going to install the shower base and make it work when you build the walls? There is little room for error once that pipe is concreted in.

BIG QUESTION IS THERE A TRAP ON THAT PIPE? If it was a floor drain with the built in trap the you have to put in a trap, in which case you should get a plumber to help with that. You will have to make a larger hole and do some plumbing, given your knowledge you should not attempt yourself. If there is no trap and you stick one on top of what is there, you will be making an S trap, which should be illegal where you live.

I SEE NO TRAP IN THE PICTURE, UNLESS IT IS UNDER THE DIRT.

 

[Stacy7]

Thanks again for all of the good information. You've given me more to consider and work on, but I want to do the best job I can!

 

[Construct30]

Is there a trap under the dirt? You have to have a trap on a sewer line.