up comes the tile and look what we found!!

Old 02-08-17, 01:48 PM
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up comes the tile and look what we found!!

We brought up the tile in my bathroom and found that the past builders poured concrete directly on plywood which eventually cracked the concrete which intern cracked the grout.

It looks like the plywood is bowing up on the side of the toilet which we don't no why.

Looks like there is a leak where you see wet plywood however this could be due to the holes in the grout and not sealed properly. We don't think the leak is coming from underground or another area.

I want to put new tile down but what I need a recommendation on how to proceed:

- rip up the plywood and see what we find?
- forget the issue and put concrete board over the plywood and tile over that and pray that plywood doesn't shift too much?

Below are pictures:

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thank you,

Old 02-08-17, 03:34 PM
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One thing that screams is the piecemeal way the plywood was installed around the toilet. NEVER only span two joists or rafters with plywood. It must go at least 3 for stability. Next you need to determine how thick your subflooring is. You should have at least 1 1/4". Another important consideration is the size of your joisting and the unsupported span across this area.

If you find that you only have 1/2" plywood, I would remove it and replace with 3/4" Advantech and 1/2" plywood. Then you can install your 1/4" CBU, thinset and tile. The water next to the tub is highly possible shower splash out getting under the tile at that joint.

Do some exploratory and let us know what you find, and include pictures.

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