Leaks with Terrazzo Shower Base - Long Post

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JuneK

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After what I'm assuming is 47 years, I have developed a leak somewhere around my terrazzo shower base. It's an upstairs bath, and I've got a wet spot in the ceiling drywall down stairs.

I know I'm due for a major remodeling, but it's not in the cards for this year. Other than stop using the shower, what's the best I can do to prevent more water damage?

I cut out a chunk of the ceiling drywall, and see water stains apparently from an edge or outside corner of the shower base that has run along the subfloor and then down the next joist away from the shower base. There is also some black staining (mildew?) and a little white fuzz (mold?) on a couple of the subfloor boards and the top of the joist where the subfloor meets it.

I don't see any other evidence of wet ceiling drywall anywhere under the base itself.

There were some cracks in the grout of the tile shower walls, and when I pulled the caulk away from the joint between the tile wall and the shower base, it was wet behind that. There is also cracking in the grout between the tile baseboard and the floor, where it meets the shower pan. These tiles (about 6 of them) move when pressed on the edge by the floor.

There are also some cracks in the cove of the shower base. Could these go all the way through the pan and cause a leak? The terrazzo is so old, that the mortar has worn away to a depth of about 1/16" inch, leaving the stone standing high. Should I try an epoxy coating to fill and seal, or just some grout? Plain epoxy, or filled with something? I'm familiar with the West brand of epoxy. Is another one better for this application?

I renewed the gout in the shower 15-20 years ago, and when the joint between the shower base and wall began cracking 5-10 years ago, sealed it with the caulk.

I'm redoing the grout again. How long should I let the walls dry out before re-grouting?

What can I do with the sub-floor and joist to clean up and limit the mold/mildew and possible dry rot? How long should I leave the ceiling open to dry out before I redo the drywall?

Thanks for any and all help!

June
 

Geniescience

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The shower cannot be used. That is the only way to prevent water from coming through.

Grout caulking and tiles do not constitute waterproofing. Your waterproofing membrane is underneath. It has failed.

Any attempt to patch the surface will lead to failure. More water will find its way through.

David
p.s. See www.johnbridge.com - discussion forums on waterproofing shower pans.
 

JuneK

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Yep, I figured the major re-model was when, not if. I was hoping to put it off for a year or so.

I think I found the source of the major leak. We finished removing the old grout, and found three tiles in the inside corner away from the shower door and wet wall that were loose - two on one wall, one on the other. Pulled them away, and found out what construction practices were like in 1959.

The backerboard is paper covered. I'm assuming some kind of cement board, as if it was standard dry wall, I would think it would be sopping wet and crumbly, but this is hard and dry under the wet paper. The backerboard stops a bit over an inch above the shower pan. It apparently wasn't a tight but joint in the corner, but had a gap, which appears to have caused the corner grouting to crack repeatedly, leading to leaks.

There is a metal lip on the terrazzo shower pan that extends up under the backerboard. Perhaps lead as it is black? Unfortunately, it's also kind of crumbly.

Best to bite the bullet and rip it all out and re-do it, I guess. Getting that terrazzo 48x32 shower pan out is (not) going to be fun <G>. I like the 2" tile flooring and it is still nice and tight after all these years - no cracks in the grouting at all. I kind of hate to break that up, but I don't see any way not to and still be able to get the pan out.

Any suggestions on how to treat the subfloor and joist(s) that are water damaged? Treat mold/mildew with a bleach solution and let dry?

Thanks for the comments.
 

Geniescience

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JuneK said:
....The backerboard stops a bit over an inch above the shower pan. It apparently wasn't a tight but joint in the corner, but had a gap.....
The gap is a good thing. Not a defect. It kept water away from the backerboard for many years.

The crumbling black stuff was your membrane, which has failed.

Post the whole description on www.johnbridge.com and you'll get interesting feedback. They are friendly.

DAvid
 
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