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Contractor
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Discussion Starter · #1 ·
I'm doing some work on a home has a slab crawlspace whcih has a few inches of water in it-it's a bank repo so no electric/pump to get rid of water.

the kitchen floor is a DIY installation-has 1/2" plywood installed over the original vinyl flooring and a failed installation of 12" tile. The tile comes up easily-poor adhesion between plywood/thinset. As I'm tearing into it, by the exterior wall I find previous signs of delamination in the original layer of plywood and the top layer of plywood is moist. failed tile adhesion is obviously b/c of high moisture content in top layer of plywood.

the question is: why is the top layer of plywood wet? afte pulling some of the vinyl sheet flooring back, the subfloor (or luaan) seems to not be wet. no signs of water coming into the room from the exterior wall. could the moisture be coming up through the wet crawlspace, then stopping at the bottom of the 12" tile and soaking the top layer of plywood?

I'm stumped as for a logical conclusion to this.
 

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Carpe Diem
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20,742 Posts
I'm doing some work on a home has a slab crawlspace whcih has a few inches of water in it-it's a bank repo so no electric/pump to get rid of water.

the kitchen floor is a DIY installation-has 1/2" plywood installed over the original vinyl flooring and a failed installation of 12" tile. The tile comes up easily-poor adhesion between plywood/thinset. As I'm tearing into it, by the exterior wall I find previous signs of delamination in the original layer of plywood and the top layer of plywood is moist. failed tile adhesion is obviously b/c of high moisture content in top layer of plywood.

the question is: why is the top layer of plywood wet? afte pulling some of the vinyl sheet flooring back, the subfloor (or luaan) seems to not be wet. no signs of water coming into the room from the exterior wall. could the moisture be coming up through the wet crawlspace, then stopping at the bottom of the 12" tile and soaking the top layer of plywood?

I'm stumped as for a logical conclusion to this.

What it sounds like to me is the water source is above the floor. It's wetting the top layer of ply and then finding its way into the basement through, perhaps a passage to the basement like a frig water line or electrical/plumbing. Vinyl is keeping everything else under it dry.
As for the failed tile, it's from the crappy DIY installation. Tile over vinyl is not the way to do it. The original vinyl should have been removed. There should have been either a membrane or CBU used directly under the tile. I doubt it was even EGP to begin with. Probably used mastic to adhere too. Sounds like the tile was doomed even before the water :rolleyes:
 

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Contractor
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Discussion Starter · #3 ·
for clarification, it was original subfloor, sheet vinyl, 1/2" plywood then tile. good call on mastic-there were some areas where it was used :-(

no utilities in the house. water is from lots of rain last week.
 

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Carpe Diem
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for clarification, it was original subfloor, sheet vinyl, 1/2" plywood then tile. good call on mastic-there were some areas where it was used :-(

no utilities in the house. water is from lots of rain last week.
I still think the source is above the floor. If it were wicking up from below the vinyl would block a lot of it so the ply wouldn't be as wet as it is.

Regardless, tile job was hacked! :furious:
 
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