Crack in shower pan!?

[J-Labrador]

Hello all,

I am renovating an old shower and was hoping to reuse the concrete shower pan. It is poured on a slab basement and was poured around shower drain and plumbing pipe. Once I removed the old tile and mortar I noticed a crack in the pan roughly along where the plumbing runs. Should I be worried about this transferring up through my new tiles? Should I use an uncoupling membrane?

[cx]

Welcome, Jay.

I'm guessing that pad was poured to raise a drain high enough to allow fall for the drain line. A photo of a larger area might give us more insight into that.

I can't tell what sort of drain you had in that big divot we see in the concrete pad. Can you show us what's in there?

What is your plan for waterproofing this shower? I trust you're not thinking you can just tile over what we're seeing in the photo.

[J-Labrador]

CX

Yes the pan was poured about 6” high to give night to allow drainage to a saniflow. I chipped out concrete around the old drain to exposed an area that I can cut back to fresh 2” and glue on a new drain.

My plan is to set a new 3 piece drain, add a new layer of thinset or dry pack to the level of my new drain, Oatey liner, lath, 1.5” finish layer of drypack, thinset and tile.

I’m just worried the crack in the pan might migrate up to the tile/grout. It is an old pan probably from at least the 80s. The crack follows the plumbing inside the pan. So maybe it cracked right after they poured and is done cracking.

[Kman]

I would remove what you have there. If the concrete heaves or settles it'll cause the tile above it to crack.

[jadnashua]

I can't tell if that surface is flat, or has a slope to the drain.

In a conventional shower construction, the preslope needs to be sloped to the drain prior to adding the liner. Concrete needs some depth to have enough strength. It appears to be fairly thin over where the drain line runs.

To minimize the height buildup, I'd tear out the concrete, then, maybe build a subfloor to clear the drain line, then consider using a sheet membrane since you then would only need a single layer of sloped mud, then the waterproof, tileable layer, rather than two layers as a conventional shower would require.

[J-Labrador]

Sorry more pics here

[J-Labrador]

Yes it is slopes to the drain roughly 1/4 per foot. Concrete is 6” at outside and yes it is thinner around drain and where plumbing runs.

Thanks everyone for the responses

[PC7060]

What Kman and Jim said. Take the slab out and rework to lower slab to reduce any change in elevation.

[cx]

Don't think that's an option for him, PC. Can't go down into the existing slab as he's got to raise his drain well above the existing basement slab to accommodate his drain line. But maybe I'm reading this wrong?

Jay, if you're gonna keep your drain above that cracked pad, there are a couple options.

1. If you elect to use a direct bonded waterproofing membrane for your receptor waterproofing, you could set the drain with as little as 3/4" of dry-pack mortar bonded to the pad, and your membrane over that. That would not provide much, if any protection from that crack telegraphing through your shower floor tile. Some such membranes would provide more protection than others, but still very risky.

2. You could put down a cleavage membrane and a reinforced mortar bed of a minimum 1 1/2" thickness with welded wire mesh in the vertical center, and your waterproofing membrane on top of that. Still no guarantee, but more protection from the crack than Plan A.

3. You could also attempt to set a clamping ring drain in that hole such that you could lay a PVC or CPE membrane over what you've got, then a minimum of 1/1/2" of mortar on top of that (reinforcement optional) and your tile on top of that. Again, some isolation from the crack, but no guarantee.

Or, of course, you could remove the concrete pad and start over with a new concrete pad or a build-up of dry-pack mortar, but you'd likely still be dealing with a cracking problem above the drain line.

2 and 3 would raise your shower floor higher than 1, but seems like you're gonna have a substantial step up over your curb, no matter what you do.

My opinion; worth price charged.

[jadnashua]

I was in an old hotel in London many years ago that had retrofitted a shower where they had to raise the pan, probably for the same reason...the step down with wet feet was a killer! I'd want a solution that had the least buildup I could.

A bonded membrane with a single layer would likely end up with the least height.

If you could build a structure such that you could put a 3/4" piece of ply on top that just cleared the drain pipe, then build a single sloped layer on top with a bonded membrane, it wouldn't be very high. If you built it so it was perfectly flat and level, you could use a preformed foam pan that would end up thinner than the thickness you'd need for a mud pan. If you built the whole buildup out of mud, you'd still have that weak, thinner section over the pipe. Lath in the layer might help, but it wouldn't be my first choice.

Another choice, might be to use something like a saniflow and pump the water but that's more expensive, and requires maintenance versus relying on gravity that's free and less complex.

[cx]

Originally Posted by Jim

Another choice, might be to use something like a saniflow and pump the water but that's more expensive, and requires maintenance versus relying on gravity that's free and less complex.

Originally Posted by Jay, Post #3

Yes the pan was poured about 6” high to give night to allow drainage to a saniflow.

Think he's already doing that with the set-up he has, Jim.

[ss3964spd]

Does a curb at the shower entrance need to be factored in?