is wall framing on top of subfloor?

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Old 04-14-13, 06:49 AM
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is wall framing on top of subfloor?

My main question is: is the wall baseplate nailed down on top of the subfloor or on top of the joists? If I need to replace the subfloor, will I have to remove the wall?
Here the story behind why I'm asking...

My wife was taking a shower in the downstairs bathroom yesterday when I hear a little clicking sound. It was water dripping from the hallway light fixture right outside the bathroom. I immediately told her to turn off the water, not knowing where the water was coming from and not knowing if electrocution was a possibility. She also noticed a water spot forming on the ceiling of the bathroom, about a foot in diameter. The upstairs bathroom is approximately over the downstairs bathroom so I started looking up there, first thinking it was the toilet supply line and later figuring out it was the toilet wax ring leaking. I also found wet carpet on the stairway landing outside the bathroom.

I removed the toilet from the flange and cleaned away the wax ring. I'm finding the subfloor seems to be soft around the toilet flange. At this point I've also removed the bathroom vanity and the carpet and padding from the stairway landing because I figure it's done. The subfloor in the landing area was very wet and the carpet tack strips had some mold.

So...I'm not sure how far I need to go. The bathroom floor has a thin layer of plywood (lauan?) on top of the subfloor, I guess to raise the height of the vinyl to the same height as the carpet on the landing. Do I need to pull up the carpet on the other side of the wall in the bedroom to check the subfloor there if the carpet isn't wet? It seems like the water ran mostly on top of the vinyl floor, under the vanity (the vanity sides touching the floor have wicked the water up) over to the wall shared with the landing and then under that wall where most of the water collected. The downstairs hallway light is approximately under this spot. If plywood subfloor is compromised, will I need to remove the wall to thoroughly remove all of the plywood? It seems like I will.

We don't use the upstairs bathroom much, so it's hard to say how long it's been leaking. I find it strange it started showing itself while the downstairs shower was being used. Any thoughts?
 
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Old 04-14-13, 06:52 AM
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The studs are erected over the subfloor. Normally you just cut out up to the wall and then install your replacement piece of plywood. A lot depends on how bad and how far under the wall the damage is.
 
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Old 04-14-13, 04:26 PM
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is the wall baseplate nailed down on top of the subfloor or on top of the joists?
The sole plate should be on top of the subfloor. Cut to that line and inspect for damage. Often just letting everything dry out for a couple of days will reveal that no real structural damage has been done.

I would install a barrier under the new subfloor in the bathroom, turned up each wall. If there's a built-in tub that will make doing that more of a challenge.

I find it strange it started showing itself while the downstairs shower was being used. Any thoughts?
Plumbing can be like that. What I find strange is that this apparently happened when the upstairs toilet had not been flushed. There should have been no water present at the wax ring to leak out unless the toilet had been flushed, or it was leaking.

Was the water really low in the bowl when you first saw it?

To avoid a leak at the wax ring, the ring must be installed at or slightly above floor lrvrl. But that's a question for the plumbing forum.
 
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Old 04-15-13, 08:49 PM
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I've discovered this is another room with sagging or bowing joists (my other post talking about the living room downstairs). The joist in the middle is about 1/8" higher than its neighbors. I suppose I could lay down new plywood as is, but this seems like a golden opportunity to fix it. Am I going to have to gut the ceiling on the first floor to fix the second floor joists? Ugh!

I've thought about shimming the low joists to bring them up to the same level, but since there is existing material around the perimeter of the room (where my circular saw can't reach because of the shoe), I would then have a step from the existing level up to the new material level where it matches up.

The best option I can come up with is to lay down the plywood subfloor, then do a coat of self-leveling compound to level the whole floor, then lay the lauan on top of that, and the vinyl sheet flooring on top of that. Are there any drawbacks or potential things that can bite me doing this?
 
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Old 04-15-13, 09:14 PM
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I'd cut up to 1-1/2" of the wall drywall, add flat 2x4 blocking to nail the perimeter of the new/old sub-floors to, gaining back the floor diaphragm shear-flow you lost by cutting it. This on lauan; UMass Amherst: Building and Construction Technology Wood Underlayments for Resilient Flooring

Underlayment tips; http://www.google.com/url?sa=t&rct=j...nbzenw&cad=rja

Gary
 
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Old 04-15-13, 09:39 PM
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Gary - are you saying cut away the floor 1.5 inches away from the walls or are you saying to cut away the drywall 1.5 up from the floor?
And then I add 2x4 blocking between the joists such that the blocks are the same height as the tallest one in the center of the room? Don't I still run into a situation where I have a step up from the existing floor to the new material fasted to the 2x4 blocking? Or would i still use the self-leveler with this?

I'm reading the second full paragraph on page 2 of the PDF and I think that agrees with what you're suggesting, but I'm still not sure how to handle that transition between the old and new OSB subfloor.
 
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Old 04-18-13, 07:55 PM
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If you cut the sub-floor sheeting right next to the drywall, you have no way to tie the floor under the wall to the new floor. Leave 1-1/2" of floor to nail through, into new blocking (either running with the floor joists or between them) and nail the perimeter of new floor into the flat blocks also. This will restore the shear flow you lost by cutting it.

You lost me on the different heights.... buy a moisture meter to press the pins in the wood/carpet pad to check for moisture content...

Gary
 
 

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