Shower pan crack in mortar bed

[rhtexas78]

So bought a house under going renovations. Previous owner had almost finished showers. One of the showers has a crack in the grout going across it from both sides of the drain. I removed the grout and a few penny tiles. Tile mortar is not cracked but the shower pan does have a crack. What are my options, redo the entire pan? Can pan be patched up? Can the crack just be regrouted? The bath floor doesn’t have a crack so I don’t think it’s a foundation issue. What could cause a crack like this in the dry pack? Thanks in advance

[cx]

Originally Posted by Rick

Tile mortar is not cracked but the shower pan does have a crack.

Need to help some of us here, Rick. By mortar bed, are you talking about the thick top mortar bed of a traditionally built shower receptor?

If so, what are you calling the "shower pan" that you indicate is cracked?

[rhtexas78]

Sorry think I’m mixing terminology. Yes, crack is in the thick sloped bed under the tiles which caused grout to also crack. Yes looks to be traditional shower pan. I did not see waterproof membrane

[cx]

OK, we'll presume a traditional shower receptor with a thick mortar bed above a waterproof liner that is connected to a clamping drain of some sort. Now we need to know a whole lot more about the construction. It's uncommon for that type of receptor construction, properly done, to develop a crack in the top mortar bed.

What is the subfloor under the shower?

Is there a pre-slope under the waterproof liner?

How thick is the top mortar bed?

Of what composition is the top mortar bed? Is it a traditional dry-pack-type material, or perhaps more like concrete?

Obviously, you'll need to do some more demolition to answer some of those questions, but it's entirely possible that you can remove the top mortar bed and salvage the receptor. If the waterproof liner is intact, and if there is a proper pre-slope, and no evidence of leakage, it might not be a total loss.

My opinion; worth price charged.

[rhtexas78]

Looks to be dry pack. Don’t think there is a preslope as thickness is maybe an inch near the drain or less. But like you said would have to demo more to figure out. Subfloor is concrete slab. Would be reasonable to remove tile around crack the fill in with thin mortar slurry consistency. Then reapply tile/grout?

[rhtexas78]

Looks to be dry pack. Don’t think there is a preslope as thickness is maybe an inch near the drain or less. But like you said would have to demo more to figure out. Subfloor is concrete slab. Would it be reasonable to remove tile around crack then fill in with thin mortar of slurry consistency. Then reapply tile/grout?

[jadnashua]

I know it happens a lot, but plumbing code requires the waterproofing to be sloped to the drain, and tile is not the waterproofing.

Total thickness around the drain with a conventional shower build is far more than 1"...

[cx]

Originally Posted by Rick

Would it be reasonable to remove tile around crack then fill in with thin mortar of slurry consistency.

Sure, if you don't care if it works, Rick.

Naaa, you wanna make a proper mortar bed. The tile industry standards call for the top mortar bed to be a of 1 1/2" uniform thickness, following the slope of the waterproof liner.

If you have no pre-slope, you have larger problems than just the cracked grout.

My opinion; worth price charged.

[rhtexas78]

Did some more demo, looks like it has some sort of liner almost like fiberglass or epoxy, but not sure never seen one like this. Top bed is uniform thickness so there does appear to be a pre slope. Problem is top bed is only about 3/4” thick. Could this be the issue. There isn’t a crack at the bottom of the hole, but whatever that material is it may be more forgiving.

[jadnashua]

I wonder if they may have used a cbu with a mesh on the surface. If so, I doubt that was designed for use on a shower floor.

[cx]

A geographic location in your User Profile might be helpful here, Rick.

[rhtexas78]

Location is central Texas

[cx]

Thought that might be the case. The People's Republic of Austin is the only place I'm aware of in the country were fiberglass waterproofing is de rigueur for tile shower receptors, even though there is no known reference to any such in building code nor tile industry standards.

I don't know just how they are made to slope properly, if, in fact, they do, but I suspect some deficiency in the support of your fiberglass liner, or perhaps just the thin mortar, or incorrect mortar, is the cause of your cracking.

About all I could suggest is that you remove the mortar completely, raise the top portion of the drain, and create a new mortar bed of the correct consistency and thickness. Might solve the problem. Might not.

My opinion; worth price charged.