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Unread 02-21-2021, 12:43 PM   #3
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Join Date: May 2018
Location: San Diego, California
Posts: 75
Hi all, I removed the tub, and it turns out that the builders of the house cut a hole in two places in the subfloor as shown in the pictures. My guess is that since these are tract housing, they left the option open for the drain to be on either side of the tub. Since there are holes here, I was able to easily measure the deflection. With 11" joists, 10' length, 16" spacing, I get a rating of L/1252, which should be more than enough for ceramic.

The wife decided on a clawfoot tub, so as a result I'll need to get rid of those holes there. I also got an 8' level, and I noticed that the floor is almost perfectly flat across all 8' spans, with at most 1/8" drop in any direction. The only spot that was dipped slightly was near where the old tub was in the picture, and I'm assuming I have to replace those boards anyways, so it shouldn't be a problem.

My questions are: as you can see in the pic, this is 3/4" OSB. Reading through these forums I'm seeing mixed messages on OSB. I see that it should be 1.25" minimum if tile are to be installed, but there was a tub on here before which I'd think is much heavier than tile with live weight. It seems the reason for not using OSB is that when it gets wet, it warps or is not as strong. Is that a problem with a waterproof layer like ditra between the tile and OSB? The adjacent room has laminate directly on the OSB, so I'd prefer not to have an extra 1/2" plywood + ditra + thinset + tile for the transition.

Second question is I want to change the wall behind the shower to be a pony wall with only glass, and no drywall above the pony height. It's not clear to me whether this is load bearing, but I don't think it is because there are no joists below it (you can see it's just copper pipes). However, the fact that they used 6 studs in just the left side and that it runs perpendicular to the joists has me concerned. Do I need someone to look at it? Picture is attached.
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Last edited by Shaklee3; 02-21-2021 at 04:04 PM.
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