Help with shower pan install cement slab

[DIYHELP]

Hello and thank you in advance for the help.
Needed: Shower pan size 36 x 36 with drain exactly in middle
Cast iron pipe is 1/2 inch below top of subfloor.
Can not get underneath to plumbing
What are my options for a shower pan. It seems it is difficult to find a shower pan with drain exactly in middle of pan. The only one I can find is the 3636M(Mustee) and it is has the integral molded drain and requires the pipe to be even with sup floor top, so the pipe would be low in the molded drain i the 3636M.

Should I be chainginng the cast iron to PVC?

In the end how will i ever know if drain is sealed or not if there is no access below

Please see pics.

Any suggestions would be greatly appreciated.

Thank you.

DIYHELP

 

[frodo]

Make a hole in the floor, using a 4 1/2'' grinder. cut the cast off at 8'' below sub floor
install 1 1/2'' cast iron x 1 1/2'' pvc transition band glue a 2x1 1/2 bushing onto the pipe, glue a 2'' coupling on the reducer

instll a no caulk shower drain on the pan, set the pan. measure and install a 2'' pipe

 

[Twowaxhack]

I would break the floor out enough to replace the old cast iron trap with PVC and take the opportunity to position it into the proper location for whatever pan you decide.

I’d hate for you to put $5k into a shower only to have the old cast iron Ptrap leaking a week, month, year later.

My showers last around 30 yrs or so. How long will that cast trap last?

 

[Twowaxhack]

I believe the pipe pictured is 2”. Keep it all 2”.

Make sure you install your riser out of the Ptrap perfectly plumb.

 

[Twowaxhack]

Make a hole in the floor, using a 4 1/2'' grinder. cut the cast off at 8'' below sub floor
install 1 1/2'' cast iron x 1 1/2'' pvc transition band glue a 2x1 1/2 bushing onto the pipe, glue a 2'' coupling on the reducer

instll a no caulk shower drain on the pan, set the pan. measure and install a 2'' pipe

If I did that, I wouldn’t use a bushing. I’d use a bell reducer.
This would transition without a coupling and it would drain with less restriction.

Put it together each way and look through it, the bell reducer is the way to go.

I think the pipe is 2” tho that’s pictured.

 

[DIYHELP]

yes 2" pipe. Thank you everyone very much. I guess I have a lot to consider. I was hoping to avoid breaking the concrete. I picked up the shower pan and it is centered nicely, however the pipe is 1/4" lower then the subfloor. The directions on the shower pan call for the pipe to be level with sub floor. So the gasket will sit a 1/4 higher then the pipe. not sure that will matter or not.

 

[Twowaxhack]

yes 2" pipe. Thank you everyone very much. I guess I have a lot to consider. I was hoping to avoid breaking the concrete. I picked up the shower pan and it is centered nicely, however the pipe is 1/4" lower then the subfloor. The directions on the shower pan call for the pipe to be level with sub floor. So the gasket will sit a 1/4 higher then the pipe. not sure that will matter or not.

The way I’m advising you to do it would eliminate the possibility of a rotten 2” cast iron trap being left under your new shower to leak.

Then you’ll be breaking it all out including your new shower.

But sure, it’s your choice.

 

[DIYHELP]

Twowaxhack, Thank you!

Also, is the 2 inch pipe sticking out of the ground(original picture above) a tail pipe placed into a trap? If so can it pulled out of the p trap?

Thanks again everyone.

 

[Twowaxhack]

Twowaxhack, Thank you!

Also, is the 2 inch pipe sticking out of the ground(original picture above) a tail pipe placed into a trap? If so can it pulled out of the p trap?
Thanks again everyone.

Can you look into the vertical pipe and see water ? If so then there’s probably a trap right there. If not it might be a dry trap and you need to pour some water in it.

If it won’t hold water then there could already be a hole in it.
Or you could have a running trap, this is where the trap is not placed directly beneath the fixture.

To test for a running trap, flush toilets connected to the same drainage system while listening into the shower pipe. If you hear water there’s no trap seal. If you don’t hear water then it’s either the drain is clogged or you have a running trap.,

I’d replace the trap with PVC.

 

[DIYHELP]

ok got it, i understand and thank again very helpful info, there is water in it, however I will check again when I get home.

However just for my own info and maybe another option. If it is a p trap does this mean the pipe sticking out of the ground is a tail pipe and I can pull it out and replace with pvc to the height I want into the existing cast iron p trap?