sunken shower

[ma740988]

Need to install a shower drain on a concrete subfloor. I've made all the cuts but I'm having a hard time with the fit check because pressure on the pipe inside the hole of my shower drain causes the pipe to move down about 1/2 inch (maybe more).

I can (with pressure) apply a coupler to the pipe inside the hole
then I attach a 2 inch pipe that extends to the surface of the concrete subfloor. From there i need to attach the drain but that requires some pressure and this is where I'm having difficult because when pressure is applied to the pipe it moves.

I'm at a loss on how to keep the pipe stationary so I can attach the drain without movement. Thoughts?

I've attached 2 jpegs. one showing the hole and pipe in the subfloor. the other is my goal.


A follow-up question. This thread (http://bedgell.com/shower/hallshower2014.html) claims there should be a 1/2 inch between top flange and subfloor. The flange i removed was flush to the floor. Whats the motivation for the 1/2 inch?

[Kman]

Welcome back.

First, the flange does need to be off the slab 3/4" to allow for the thickness of the mud bed under the liner. That bed will slope the liner so that water follows it to the drain.

Can you see the drain trap below? Usually just some gravel below the trap will keep it from moving down.

[cx]

Welcome back, MP. Same shower that was gonna be a Kerdi shower couple years back?

[ma740988]

To fill the hole around the pipe, one guy recommends gravel; another a mix of cement up to a certain level and gravel; a third mud deck. thoughts?

Can you see the drain trap below? Usually just some gravel below the trap will keep it from moving down.

Kman: Unfortunately no. There's a thick black material (not sure what the official name is and I've googled and came up short) that surrounds the pipe. I tried moving the material out of the way to see if I can reach the end of the drain trap but came up short. Would hate to have to rip into the concrete.

Cx: Yes. Life comes at you fast sometimes man so had to deal a parent dying .. I've ditched the kerdi idea and watched a ton of videos that promotes the traditional approach which I've grown to love.

[Kman]

I would put some tissue in the pipe to block it from catching trash, then see if you can get some gravel down underneath.

I'd rather know what you have there, but I don't know what that black material is either.

Is this a slab on grade?

[Davy]

I would bust more concrete out. You'll need to pack more dirt in the bottom once the drain is in place and then more concrete to tie into the slab. That helps support it all. And, like Kevin said, the bottom flange needs to be up off the slab enough for the preslope.

[ma740988]

I have a layer of mud deck on my pan liner that was cured overnight. I just checked an area with my leveler and discovered (not sure how I missed this yesterday) I could raise one side a tad.

One option I saw online is to add a little extra thinset to the problem area and call it done. The question. adding mud deck on top of the cured mud deck shouldn’t be a problem? It’s a small area and just weighing my options.

[Davy]

You can fill any small divots and fine tune the deck mud using thinset if it's only 1/8 thick or so. I'd vacuum first.